1
|
Synergistic Improvement of Dielectric and Thermal Conductivity Properties for Polymers Filled with Multifunctional Modified Nanowires. ACS APPLIED MATERIALS & INTERFACES 2023; 15:58828-58838. [PMID: 38051817 DOI: 10.1021/acsami.3c13359] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/07/2023]
Abstract
Dielectric composites are widely used in power electronics, power systems, aerospace, and other fields due to their extremely high power density. However, if their energy density can be further increased, the application range will be greatly improved. Improving the dielectric constant of composites is one of the most effective ways to increase the energy density. In this study, a preparation method for copper calcium titanate nanowires (CCTO-NWs) with adjustable aspect ratio was investigated. Upon incorporation of these CCTO-NWs into the polymer matrix, the nanocomposites exhibit a significantly higher dielectric constant and a lower dielectric loss. In addition, a thin layer of Al2O3 with excellent thermal conductivity is coated on the surface of the CCTO-NWs to form a core-shell structure nanowire CCTO-NW@Al2O3. The introduction of the thermal conductive layer of Al2O3 not only creates a continuous heat transfer path within the dielectric composite, increasing the thermal conductivity of the composite from 0.11 W/(m·K) of pure HIPS to 1.12 W/(m·K), but also serves as a buffer layer between HIPS and CCTO-NWs, effectively alleviating the electric field distortion caused by the large difference in the dielectric constant between them, thereby optimizing the dielectric properties of the composite and reducing the dielectric permeability threshold from 30 to 20 vol %. This work provides an effective strategy for synergistically improving the dielectric constant and thermal conductivity of dielectric composites while also taking into account the good flexibility of polymer/ceramic nanocomposites.
Collapse
|
2
|
A Fluorine-Containing Main-Chain Benzoxazine/Epoxy Co-Curing System with Low Dielectric Constants and High Thermal Stability. Polymers (Basel) 2023; 15:4487. [PMID: 38231900 PMCID: PMC10707784 DOI: 10.3390/polym15234487] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2023] [Revised: 10/29/2023] [Accepted: 11/07/2023] [Indexed: 01/19/2024] Open
Abstract
A fluorine-containing main-chain benzoxazine (BAF-M-TB) was co-cured with biphenyl epoxy for the integrated circuit industry. The benzoxazine precursor was synthesized using 4,4'-(Hexafluoroisopropylidene)diphenol (bisphenol AF), 2,2'-Dimethyl-[1,1'-biphenyl]-4,4'-Diamine(M-TB), and paraformaldehyde. In addition, the 3,3'-(Oxybis(4,1-phenylene))bis(3,4-dihydro-2H-benzo[e][1,3]oxazine) (Benoxazine ODA-BOZ), which is a commercialized benzoxazine, was co-cured with biphenyl epoxy as a control. The two co-curing systems were referred to as EP/BAF-M-TB and EP/ODA-BOZ. The curing kinetics, rheological behavior, and thermal stability of the two co-curing systems were studied. Poly-EP/BAF-M-TB and poly-EP/ODA-BOZ quartz fiber cloth reinforced composites (QFRPs) were prepared using the prepreg laminating method in order to determine their mechanical, thermal, and dielectric properties. Both of them showed good thermal properties and dielectric properties. The dielectric constant of poly-EP/BAF-M-TB QFRP is in the range of 3.25-3.54 at the low frequency of 10 kHz-10 MHz. At the high frequency of 5 GHz, its dielectric constant is 3.16, which is better than that of poly-EP/ODA-BOZ QFRP. Additionally, the Td5 of poly-EP/BAF-M-TB was 398 °C in a nitrogen atmosphere, which is higher than that of poly-EP/ODA-BOZ.
Collapse
|
3
|
Energy Storage Performance of Polymer-Based Dielectric Composites with Two-Dimensional Fillers. NANOMATERIALS (BASEL, SWITZERLAND) 2023; 13:2842. [PMID: 37947688 PMCID: PMC10650859 DOI: 10.3390/nano13212842] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2023] [Revised: 10/09/2023] [Accepted: 10/18/2023] [Indexed: 11/12/2023]
Abstract
Dielectric capacitors have garnered significant attention in recent decades for their wide range of uses in contemporary electronic and electrical power systems. The integration of a high breakdown field polymer matrix with various types of fillers in dielectric polymer nanocomposites has attracted significant attention from both academic and commercial sectors. The energy storage performance is influenced by various essential factors, such as the choice of the polymer matrix, the filler type, the filler morphologies, the interfacial engineering, and the composite structure. However, their application is limited by their large amount of filler content, low energy densities, and low-temperature tolerance. Very recently, the utilization of two-dimensional (2D) materials has become prevalent across several disciplines due to their exceptional thermal, electrical, and mechanical characteristics. Compared with zero-dimensional (0D) and one-dimensional (1D) fillers, two-dimensional fillers are more effective in enhancing the dielectric and energy storage properties of polymer-based composites. The present review provides a comprehensive overview of 2D filler-based composites, encompassing a wide range of materials such as ceramics, metal oxides, carbon compounds, MXenes, clays, boron nitride, and others. In a general sense, the incorporation of 2D fillers into polymer nanocomposite dielectrics can result in a significant enhancement in the energy storage capability, even at low filler concentrations. The current challenges and future perspectives are also discussed.
Collapse
|
4
|
Regulatable Phase Manipulation-Enhanced Polarization and Conductance Loss Enabling Hierarchical 3D Microsphere-like MoS 2 with Efficient Microwave Absorption. ACS APPLIED MATERIALS & INTERFACES 2023. [PMID: 37878782 DOI: 10.1021/acsami.3c09511] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2023]
Abstract
Molybdenum disulfide (MoS2) has become a new type of microwave absorption (MA) material due to the abundant functional groups and defects, high polarization effect, and controllable structural design. However, the development of MoS2 has been limited by its inherently low conductance losses and imperfect impedance matching. This study employs ammonium ion (NH4+) intercalation as a phase manipulation strategy to enhance dielectric loss and form heterogeneous structures by incorporating highly conductive 1T phase into the 2H-MoS2 crystal phase. Additionally, the implementation of CTAB as a soft template agent for constructing layered three-dimensional microsphere structures improves impedance matching. The experimental findings demonstrate that the MA performance of MoS2 can be effectively regulated by controlling the 1T phase content and morphological structure design. It is worth noting that A-MoS2-2 possesses excellent multifrequency absorption capability. A-MoS2-2 has a minimum reflection loss (RL) of -53 dB at a coating thickness of 1.99 mm and an effective absorption bandwidth (EAB) of 5.6 GHz at a thinner coating thickness of 1.77 mm. This work improves the MA properties of MoS2 by introducing metallic phases and unique structural design, which opens up new ideas for the development of MA materials.
Collapse
|
5
|
A Rigid-Flexible and Multi-Siloxane Bridge Strategy for Toughening Epoxy Resin with Promising Flame Retardancy, Mechanical, and Dielectric Properties. Int J Mol Sci 2023; 24:14059. [PMID: 37762362 PMCID: PMC10531251 DOI: 10.3390/ijms241814059] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2023] [Revised: 09/05/2023] [Accepted: 09/07/2023] [Indexed: 09/29/2023] Open
Abstract
Developing highly efficient and multifunctional epoxy resins (EPs) that overcome the shortcomings of flammability and brittleness is crucial for pursuing sustainable and safe application but remains a huge challenge. In this paper, a novel biomass-containing intumescent flame retardant containing a rigid-flexible and multi-siloxane bridge structure (DPB) was synthesized using siloxane; 9,10-dihydro-9-oxa-10-phosphaphenanthrene 10-oxide (DOPO); and biomass vanillin. DPB could facilitate the formation of a carbon residual with an intumescent structure, which effectively blocked the propagation of heat and oxygen. As a result, the peak heat release rate (pHRR) and total heat release (THR) of DPB/EP-7.5 decreased by 38.8% and 45.0%, respectively. In terms of mechanical properties, the tensile and flexural elongations at break of DPB/EP-7.5 increased by 77.2% and 105.3%, respectively. Impressively, DPB/EP-7.5 had excellent dielectric properties, with a dielectric constant of 2.5-2.9. This was due to the Si-O bonds (multi-siloxane bridges) contained in DPB/EP, which can quench the polarization behavior of the hydroxyl group. This paper provides a facile strategy for the preparation of multifunctional EP, which will pave the way for the promotion and application of EP in the high-end field.
Collapse
|
6
|
Dielectric phenomena of multiferroic oxides at acoustic- and radio-frequency. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2023; 35. [PMID: 37531969 DOI: 10.1088/1361-648x/acecf0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/25/2023] [Accepted: 08/02/2023] [Indexed: 08/04/2023]
Abstract
In this review, an overview of acoustic- and radio-frequency frequency dielectric properties of multiferroic oxides, the significant dynamic response of electrical polarization to small external ac electrical fields, are present based on the reports in literatures and our recent experimental progresses. The review is begun with some basic terms, concepts and mechanisms associated with dielectric response and dielectric anomalies, namely dielectric peak and plateau upon varying temperatures and dielectric relaxations upon varying frequencies. Subsequently, a variety of quantitative analyses and descriptions of various dielectric effects, including dielectric relaxation, relaxational and transport dynamics, ac conductivity, equivalent circuit models and impedance spectroscopy, are summarized in details. Next is the kernel section. We thoroughly outline various physical mechanisms behind acoustic-/radio-frequency dielectric responses and anomalies of multiferroic oxides. Spin order transition/spin rotation, charge disorder-order transition, exchange striction of the spin interactions, spin-dependentp-dhybridization mechanism, quantum electric-dipole liquids, the interaction of spin order and quantum paraelectric, the motions of charged defects and carriers, quasi-intrinsic and extrinsic heterogeneous interfaces, polar relaxor and multiglass, ferroic domain wall/boundary motions, etc, are involved in these mechanisms. Meanwhile, particular emphasis is placed on intrinsic or extrinsic magnetodielectric effects and related mechanisms in multiferroic oxides. Finally, the review ends with a short perspective of future dielectric research in multiferroic oxides. This review is able to provide the detailed and unique insights into abundant underlying fundamental physics in multiferroic oxides as well as the potential multiferroics-based technological applications.
Collapse
|
7
|
Conductive Metal-Organic Frameworks with Tunable Dielectric Properties for Boosting Electromagnetic Wave Absorption. ACS NANO 2023. [PMID: 37350557 DOI: 10.1021/acsnano.3c02170] [Citation(s) in RCA: 20] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 06/24/2023]
Abstract
Metal-organic frameworks (MOFs) manifest enormous potential in promoting electromagnetic wave (EMW) absorption thanks to the tailored components, topological structure, and high porosity. Herein, rodlike conductive MOFs (cMOFs) composed of adjustable metal ions of Zn, Cu, Co, or Ni and ligands of hexahydroxytriphenylene (HHTP) are prepared to attain tunable dielectric properties for a tailored EMW absorption. Specifically, the influences of the cMOFs' composition, charge transport characteristic, topological crystalline structure, and anisotropy microstructure on dielectric and EMW absorption performance are ascertained, advancing the understanding of EMW attenuation mechanisms of MOFs. The boosted conductive and polarization losses derived from the conjugation effects and terminal groups, as well as shape anisotropy, lead to a prominent EMW absorption of the cMOFs. The Cu-HHTP confers a minimum reflection loss (RLmin) of -63.55 dB at the thickness of 2.9 mm and a maximum effective absorption bandwidth of 5.2 GHz. Moreover, Zn-HHTP showcases the absorption superiority in the S-band (2-4 GHz) with an RLmin of -62.8 dB at a thickness of 1.9 mm. This work not only hoists the mechanistic understanding of the structure-function relationships for the cMOFs but also offers guidelines for preparing functional MOF materials.
Collapse
|
8
|
Progress in Preparation and Properties of Porous Silicon Nitride Ceramics. SILICON 2023. [PMCID: PMC10240459 DOI: 10.1007/s12633-023-02525-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2023] [Accepted: 05/19/2023] [Indexed: 07/30/2023]
Abstract
Porous silicon nitride ceramics is a promising functional ceramic material. In recent years, the research on the preparation of porous silicon nitride ceramics within different methods has been widely investigated. First, this work reviews the main synthesis methods of Si3N4 porous ceramics in detail, and compares the differences between strength and porosity caused by each method. The characteristics and advantages of different technologies under the current conditions were evaluated. Second, the dielectric properties, sound absorption properties and permeability properties of silicon nitride ceramics were compared and summarized based on the experimental results. Third, the applications fields of porous silicon nitride ceramics, such as smelting industry, catalyst carrier, sound absorption, wave-transparent, and biomedical fields were explored. Finally, the assessment of different silicon nitride ceramics preparation technologies was elaborated. This review gives an outlook on the porous silicon nitride ceramics, which shows great potential for further research in this field.
Collapse
|
9
|
Polarity and Dielectric Property Control Triggered by a Coordinated Solvent Molecule Exchange in Luminescent Mononuclear Aluminium(III) Complexes. Chemistry 2023:e202203937. [PMID: 37017134 DOI: 10.1002/chem.202203937] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2022] [Revised: 04/04/2023] [Accepted: 04/05/2023] [Indexed: 04/06/2023]
Abstract
The development of molecule-based multifunctional switchable materials, exhibiting a switch of polarity and dielectric property, are extremely limited. Herein, we demonstrated solvent-vapour-induced reversible molecular rearrangements between non-polar crystals [Al(sap)(acac)(sol)] (H2sap = 2-salicylideneaminophenol, acac = acetylacetonate, sol = MeOH (1), EtOH (2)) and polar crystal [Al(sap)(acac)(DMSO)] (3). This crystal-to-crystal structural transformation was accompanied by a switch of second harmonic generation (SHG) and dielectric properties, including the formation of ferroelectric domains, reflecting the SHG-active polar Cc space group of 3. This is the first reported example of dielectric properties and polarity switching in luminescent mononuclear aluminium(III) complexes, which exhibit the strong green emission in the solid state.
Collapse
|
10
|
Quality Attributes and Dielectric Properties of Sea Buckthorn Berries under Differing Freezing Regimes and Their Interrelationships. Foods 2022; 11:foods11233825. [PMID: 36496633 PMCID: PMC9739572 DOI: 10.3390/foods11233825] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2022] [Revised: 11/24/2022] [Accepted: 11/25/2022] [Indexed: 11/29/2022] Open
Abstract
Fruit quality attributes interrelate with their dielectric properties, but such interrelationships in sea buckthorn berries under differing freezing regimes remain uninvestigated. Sea buckthorn (Hipophae rhamnoides L., cv. Shenqiuhong) berries were frozen at different temperatures (-13, -30, -35 and -40 °C) and stored for different periods (15, 30, 45, 60, 75 and 90 d). Seven quality attributes and nine dielectric parameters were measured to evaluate the effect of different frozen storage regimes on those attributes and parameters. The results showed that shorter time and lower temperature contributed to the preservation of berries quality. The dielectric parameters values increased with decreasing temperature and with the increase of freezing duration. The quality prediction models were established by the principal component analysis of the dielectric properties at characteristic frequency. The results are expected to provide a way to evaluate quality of frozen sea buckthorn berries by dielectric properties.
Collapse
|
11
|
Fluorine-Containing Flow Modifier for BN/PPS Composites Enabled by Low Surface Energy. Molecules 2022; 27:molecules27228066. [PMID: 36432166 PMCID: PMC9697440 DOI: 10.3390/molecules27228066] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2022] [Revised: 11/14/2022] [Accepted: 11/17/2022] [Indexed: 11/22/2022] Open
Abstract
In this study, a fluorine-containing flow modifier (Si-DF) with low surface energy is successfully synthesized, which is applied to fabricate ideal electronic packaging materials (BN/PPS composites) with high thermal conductivity, excellent dielectric properties, processability, and toughness by conventional melt blending. Si-DPF is located at the interface between the BN fillers and the PPS matrix, which not only improves the dispersion of BN fillers but also strengthens the interaction. With the help of 5 wt% Si-DF, BN/PPS/Si-DF (70/25/5) still exhibits the high thermally conductive coefficient (3.985 W/m·K) and low dielectric constant (3.76 at 100 MHz) although BN fillers are loaded as high as 70 wt%. Moreover, the sample processes a lower stable torque value (2.5 N·m), and the area under the stress-strain curves is also increased. This work provides an efficient way to develop high-performance polymer-based composites with high thermally conductive coefficients and low dielectric constants for electronic packaging applications.
Collapse
|
12
|
Nano-Sized Calcium Copper Titanate for the Fabrication of High Dielectric Constant Functional Ceramic-Polymer Composites. Polymers (Basel) 2022; 14:polym14204328. [PMID: 36297907 PMCID: PMC9607502 DOI: 10.3390/polym14204328] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2022] [Revised: 09/22/2022] [Accepted: 10/08/2022] [Indexed: 11/07/2022] Open
Abstract
A novel calcium copper titanate (CaCu3Ti4O12)–polyvinylidene fluoride composite (CCTO@PVDF) with Cu-deficiency was successfully prepared through the molten salt-assisted method. The morphology and structure of polymer composites uniformly incorporated with CCTO nanocrystals were characterized. At the same volume fraction, the CCTOs with Cu-deficiency displayed higher dielectric constants than those without post-treatment. A relatively high dielectric constant of 939 was obtained at 64% vol% CCTO@PVDF content, 78 times that of pure PVDF. The high dielectric constants of these composites were attributed to the homogeneous dispersion and interfacial polarization of the CCTO into the PVDF matrix. These composites also have prospective applications in high-frequency regions (106 Hz). The enhancement of the dielectric constant was predicted in several theoretical models, among which the EMT and Yamada models agreed well with the experimental results, indicating the excellent distribution in the polymer matrix.
Collapse
|
13
|
Quantifying the Improvement in Dielectric Properties of BaSrTiO 3-Based Ceramics by Adding MgO. MATERIALS 2022; 15:ma15082875. [PMID: 35454567 PMCID: PMC9030927 DOI: 10.3390/ma15082875] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/22/2022] [Revised: 03/07/2022] [Accepted: 03/13/2022] [Indexed: 02/01/2023]
Abstract
Barium titanate (BaTiO3, BT) is the main raw material of multilayer ceramic capacitors. As thinner layers of dielectric elements require smaller BT grain diameters, BT-MgO composites have been widely studied owing to the plasticity of MgO and its inhibition of grain growth. However, further improvements of the dielectric properties of the BT-MgO system are still urgently needed. Herein, composite ceramics of Ba0.7Sr0.3Ti0.9925Tm0.01O3 (BST)-x mol% MgO (x = 1, 2, 3, 4, 5) were prepared. The dielectric constant of BST-1 mol% MgO at room temperature was approximately 3800, which was 1/3 times higher than that of BT-MgO composite ceramics. The dielectric loss was less than 0.004 and 2/3 that of BT-MgO composite ceramics. The Curie temperature of BST doped with MgO was below 0 °C. The anomalous increase in dielectric constant was caused by the co-doping of Sr and Tm with BT, while the reduced dielectric loss was due to the uniform dispersion of MgO at grain boundaries, which hinders grain growth. The Curie temperature shift was mainly due to accumulated oxygen vacancies. Thus, this work provides new solutions to further improve the dielectric properties of the BT-MgO system, including changing the doping elements and adjusting the doping ratio.
Collapse
|
14
|
One-pot synthesis of hexafluorobutyl acrylate hyperbranched copolymer for graphene/poly(vinylidenefluoride-trifluoroethylene- chlorofluoroethylene) dielectric composite. NANOTECHNOLOGY 2022; 33:215703. [PMID: 35168218 DOI: 10.1088/1361-6528/ac5543] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/07/2022] [Accepted: 02/15/2022] [Indexed: 06/14/2023]
Abstract
Dielectric polymer film capacitor is rapidly emerging as next-generation energy storage for advanced engineering applications because of its lightweight, low cost, and processability. Further increasing energy density of polymer film with high charge-discharge efficiency is prevalent research spotlight. The filler/polymer composite with compatible interface is proved as an effective strategy to improve the energy storage capability of dielectric film. In this work, we designed hyperbranched hexafluorobutyl acrylate copolymer as miscible interface in graphene/fluoropolymer dielectric composite. A facile one-pot method was adopted to synthesize hyperbranched polyethylene grafted hexafluorobutyl acrylate (HBPE-g-HFBA) copolymer, which was adsorbed on surface of nanosheets by non-covalent interaction during exfoliation of natural graphite. The graphene/poly(vinylidene fluoride-trifluoroethylene-chlorofluoroethylene) (P(VDF-TrFE-CFE)) composite was prepared by solution casting. The interfacial polarization is enhanced with the improved compatibility of composite that is due to the chemical similarity between hexafluorobutyl acrylate segments and fluoropolymer matrix. The energy density of 0.1 wt% nanocomposite achieves 5.0 J cm-3with charge-discharge efficiency of 78.1% at 250 MV m-1. This work provides an optional route for non-covalent functionalization of graphene and the development of flexible polymer film capacitor with large energy storage capability.
Collapse
|
15
|
Nonsolid TiO x Nanoparticles/PVDF Nanocomposite for Improved Energy Storage Performance. ACS APPLIED MATERIALS & INTERFACES 2022; 14:8226-8234. [PMID: 35112828 DOI: 10.1021/acsami.1c18544] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Nanofiller/polymer nanocomposites are promising dielectrics for energy harvesting to be applied in wearable and flexible electronics. The structural design of the nanofillers plays a vital role to improve the energy storage performance of the related nanocomposites. Here, we fabricate a flexible device based on nonsolid titanium oxide (TiOx) nanoparticles/poly(vinylidene fluoride) (PVDF) to achieve enhanced energy storage performance at low loading. The room-temperature oxidation method is used to oxidize two-dimensional MXene (Ti3C2Tx) flakes to form partially hollow TiOx nanoparticles. Taking advantage of this structure, the flexible TiOx nanoparticles/PVDF nanocomposite with an ultralow loading content of 1 wt % nanofillers shows high energy storage performance, including a dielectric constant of ≈22 at 1 kHz, a breakdown strength of ≈480 MV m-1, and an energy storage density of 7.43 J cm-3. The finite element simulation further reveals that the optimization of the energy storage performance is ascribed to the lower electric potential among the partially hollow TiOx nanoparticles, which enhances the breakdown strength of the nanocomposites. This work opens a new avenue to structurally design and fabricate low-loading polymer-based nanocomposites for energy storage applications in next-generation flexible electronics.
Collapse
|
16
|
[Comparison of dielectric properties of normal human esophagus and esophageal cancer using an open-ended coaxial probe]. NAN FANG YI KE DA XUE XUE BAO = JOURNAL OF SOUTHERN MEDICAL UNIVERSITY 2021; 41:1741-1746. [PMID: 34916203 PMCID: PMC8685712 DOI: 10.12122/j.issn.1673-4254.2021.11.21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Indexed: 06/14/2023]
Abstract
OBJECTIVE To study the difference in dielectric properties (relative permittivity and electrical conductivity) between normal human esophageal tissues and esophageal cancer tissues resected in esophageal cancer surgery for rapid identification of esophageal cancer during surgery. METHODS An open- end coaxial probe in the frequency range of 50 MHz to 4 GHz was used for dielectric measurement of the normal tissues and tumor tissues immediately after resection in 51 esophageal cancer cases. The difference in dielectric characteristics of the tissues was analyzed in the full frequency range, and the measurement data at 6 specific frequencies (64, 128, 298, 433, 915, and 2450 MHz) were analyzed statistically. The Cole-Cole model was used for data fitting in the entire frequency band and the measured values were compared with reported values. RESULTS In the frequency range of 50 MHz- 4 GHz, the dielectric measurement values of esophageal cancer tissues were significantly higher than those of normal esophageal tissues. At the 6 specific frequencies, the dielectric properties also differed significantly between normal esophageal tissues and esophageal cancer tissues (P < 0.01). The Cole-Cole model achieved a good fitting result of the measured data. The measured values in this study were lower than the reported values. CONCLUSION There are significant differences in the dielectric properties between normal esophageal tissue and tumor tissue, which may provide a new theoretical basis for rapid identification of esophageal cancer during surgery.
Collapse
|
17
|
Enhanced Ferroelectric, Dielectric Properties of Fe-Doped PMN-PT Thin Films. NANOMATERIALS 2021; 11:nano11113043. [PMID: 34835806 PMCID: PMC8618164 DOI: 10.3390/nano11113043] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/14/2021] [Revised: 11/03/2021] [Accepted: 11/06/2021] [Indexed: 11/30/2022]
Abstract
Fe-doped 0.71Pb(Mg1/3Nb2/3)O3-0.29PbTiO3 (PMN-PT) thin films were grown in Pt/Ti/SiO2/Si substrate by a chemical solution deposition method. Effects of the annealing temperature and doping concentration on the crystallinity, microstructure, ferroelectric and dielectric properties of thin film were investigated. High (111) preferred orientation and density columnar structure were achieved in the 2% Fe-doped PMN-PT thin film annealed at 650 °C. The preferred orientation was transferred to a random orientation as the doping concentration increased. A 2% Fe-doped PMN-PT thin film showed the effectively reduced leakage current density, which was due to the fact that the oxygen vacancies were effectively restricted and a transition of Ti4+ to Ti3+ was prevented. The optimal ferroelectric properties of 2% Fe-doped PMN-PT thin film annealed at 650 °C were identified with slim polarization-applied field loops, high saturation polarization (Ps = 78.8 µC/cm2), remanent polarization (Pr = 23.1 µC/cm2) and low coercive voltage (Ec = 100 kV/cm). Moreover, the 2% Fe-doped PMN-PT thin film annealed at 650 °C showed an excellent dielectric performance with a high dielectric constant (εr ~1300 at 1 kHz).
Collapse
|
18
|
Effects of Multi-Components on the Microwave Absorption and Dielectric Properties of Plasma-Sprayed Carbon Nanotube/Y 2O 3/ZrB 2 Ceramics. NANOMATERIALS 2021; 11:nano11102640. [PMID: 34685079 PMCID: PMC8540797 DOI: 10.3390/nano11102640] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/13/2021] [Revised: 09/29/2021] [Accepted: 10/01/2021] [Indexed: 11/16/2022]
Abstract
Carbon nanotube (CNT)-reinforced Y2O3/ZrB2 ceramics were fabricated via planetary ball milling and atmospheric-pressure plasma spraying for the first time. The phase composition, micromorphology, and electromagnetic (EM) wave absorption performance of the Y2O3/ZrB2/CNT hybrid was investigated from 8.2 to 12.4 GHz. Both the real and imaginary parts of the complex permittivity were enhanced as the ZrB2 and CNT content increased. The Y2O3/ZrB2/CNT hybrids corresponded to a ZrB2 content of 15 wt.%, and the CNT content was 2 wt.% and showed an exceptional EM wave absorption capability, with a minimum reflection loss of −25.7 dB at 1.9 mm thickness, and the effective absorption band was in a full X-band. These results indicate that an appropriate CNT or ZrB2 content can tune the complex permittivity and absorption performance of the Y2O3/ZrB2/CNT ceramics.
Collapse
|
19
|
Quantitatively determining the somatic cell count of raw milk using dielectric spectra and support vector regression. J Dairy Sci 2021; 105:772-781. [PMID: 34600709 DOI: 10.3168/jds.2021-20828] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2021] [Accepted: 08/20/2021] [Indexed: 11/19/2022]
Abstract
To investigate the potential of dielectric spectroscopy in quantitatively determining the somatic cell count (SCC) of raw milk, the dielectric spectra of 301 raw milk samples at different SCC were collected using coaxial probe technology in the frequency range of 20 to 4,500 MHz. Standard normal variate, Mahalanobis distance, and joint x-y distances sample division were used to pretreat spectra, detect outliers, and divide samples, respectively. Principal component analysis and variable importance in projection (VIP) methods were used to reduce data dimension and select characteristic variables (CVR), respectively. The full spectra, 16 principal components obtained by principal component analysis, and 86 CVR selected by VIP were used as inputs, respectively, to establish different support vector regression models. The results showed that the nonlinear support vector regression models based on the full spectra and selected CVR using VIP had the best prediction performance, with the standard error of prediction and residual predictive deviation of 0.19 log SCC/mL and 2.37, respectively. The study provided a novel method for online or in situ detection of the SCC of raw milk in production, processing, and consumption.
Collapse
|
20
|
Growth, Properties and Applications of Bi 0.5Na 0.5TiO 3 Ferroelectric Nanomaterials. NANOMATERIALS 2021; 11:nano11071724. [PMID: 34209157 PMCID: PMC8307907 DOI: 10.3390/nano11071724] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/24/2021] [Revised: 06/17/2021] [Accepted: 06/24/2021] [Indexed: 11/16/2022]
Abstract
The emerging demands for miniaturization of electronics has driven the research into various nanomaterials. Lead-free Bi0.5Na0.5TiO3 (BNT) ferroelectric nanomaterials have drawn great interest owing to their superiorities of large remanent polarization, high pyroelectric and piezoelectric coefficients, unique photovoltaic performance and excellent dielectric properties. As attractive multifunctional ferroelectrics, BNT nanomaterials are widely utilized in various fields, such as energy harvest, energy storage, catalysis as well as sensing. The growing desire for precisely controlling the properties of BNT nanomaterials has led to significant advancements in material design and preparation approaches. BNT ferroelectric nanomaterials exhibit significant potential in fabrication of electronic devices and degradation of waste water, which pushes forward the advancement of the Internet of things and sustainable human development. This article presents an overview of research progresses of BNT ferroelectric nanomaterials, including growth, properties and applications. In addition, future prospects are discussed.
Collapse
|
21
|
Constructing a Microcapacitor Network of Carbon Nanotubes in Polymer Blends via Crystallization-Induced Phase Separation Toward High Dielectric Constant and Low Loss. ACS APPLIED MATERIALS & INTERFACES 2020; 12:26444-26454. [PMID: 32425040 DOI: 10.1021/acsami.0c04575] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Tailoring the distribution of nanoparticles and further constructing effective microcapacitors in polymer blends are important issues for developing high-performance polymer dielectric nanocomposites. The common method to control the selective localization of nanoparticles in an immiscible polymer blend is relatively difficult and it easily results in the accumulation of nanoparticles in one component, which usually leads to a dramatic increase of the dielectric loss in the nanocomposites. In this work, a novel strategy based on step-by-step crystallization has been proposed to tailor the refined distribution and dispersion of carbon nanotubes (CNTs) in a melt-miscible blend poly(butylene succinate)/poly(vinylidene fluoride) (PBS/PVDF) through the crystallization-induced phase separation and the engineered interfacial affinity between CNTs and polymer components to acquire high dielectric constant and low dielectric loss. The results reveal that PBS is excluded along the growth front of PVDF spherulites and locates in the margin areas of PVDF spherulites during the step-by-step crystallization process. Moreover, because of the higher interfacial interaction between CNTs and PBS, CNTs are located in the PBS-rich domain, resulting in a high concentration of CNTs in the interspherulites of PVDF. Thus, the dielectric constants of the nanocomposites are greatly improved by nearly 5-24 times compared with the nanocomposites achieved by quick cooling and, simultaneously, the dielectric loss of the nanocomposites is still maintained at a low level. This work shows that the step-by-step crystallization method can be used to fabricate the nanocomposites with a synergistic increase in the dielectric performance due to the formation of a refined microcapacitor assembly. To the best of our knowledge, this is the first report to show that the dielectric constant of the nanocomposites can be greatly enhanced just through the crystallization-optimized distribution and dispersion of CNTs in immiscible polymer blends, and it possibly gives a new technical route for the fabrication of advanced dielectric composites.
Collapse
|
22
|
Dielectric Properties and Electromagnetic Wave Absorbing Performance of Single-Source-Precursor Synthesized Mo 4.8Si 3C 0.6/SiC/C free Nanocomposites with an In Situ Formed Nowotny Phase. ACS APPLIED MATERIALS & INTERFACES 2020; 12:16912-16921. [PMID: 32182413 DOI: 10.1021/acsami.0c01277] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
For the first time, dielectric properties and electromagnetic wave (EMW) absorbing performance of single-source-precursor derived Mo4.8Si3C0.6/SiC/Cfree ceramic nanocomposites with a highly electrically conductive intermetallic Nowotny phase (NP, i.e., Mo4.8Si3C0.6) are reported. High-temperature phase evolution of the nanocomposites reveals that free carbon (Cfree) plays a crucial role in the in situ formation of the NP, indicating that the microstructure of the nanocomposites can be tailored via molecular design of the single-source precursors. Compared with SiC/Cfree and MoSi2/SiC/Cfree nanocomposites obtained under the same conditions, the Mo4.8Si3C0.6/SiC/Cfree nanocomposites exhibit significantly enhanced EMW absorbing performance. A minimum reflection loss (RL) of -59 dB was achieved at 8 GHz for the thickness of 2.46 mm, proving the superiority of the Mo4.8Si3C0.6/SiC/Cfree nanocomposite as an outstanding EMW absorbing material. On the basis of our previous discovery that the Mo4.8Si3C0.6 embedded in a SiC-based matrix with high specific surface area exhibits excellent electrocatalytic properties suitable for the electrochemical hydrogen evolution reaction, the present results prove that Mo4.8Si3C0.6/SiC/Cfree nanocomposites have to be considered as novel multifunctional materials with tailorable microstructure and excellent performance in two different fields including electrochemical water splitting and EMW absorption.
Collapse
|
23
|
Enhanced Dielectric Properties of a Poly(dimethyl siloxane) Bimodal Network Percolative Composite with MXene. ACS APPLIED MATERIALS & INTERFACES 2020; 12:16805-16814. [PMID: 32186174 DOI: 10.1021/acsami.0c01409] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Excellent comprehensive dielectric properties (including dielectric constant and loss) are essential for electromechanical transducers. This work introduced a bimodal network composite with poly(dimethyl siloxane) (PDMS) and delaminated Ti3C2Tx sheets (d-Ti3C2Tx) modified with hyperbranched polysiloxane (HPSi) (referred to as HPSi-d-Ti3C2Tx). Before the final cross-linking, HPSi-d-Ti3C2Tx, trapped with short-chain PDMS (CS-PDMS) and long-chain PDMS (CL-PDMS), was pre-reacted, which formed a distinct bimodal network structure. d-Ti3C2Tx/PDMS and HPSi-d-Ti3C2Tx/PDMS composites with different filler loadings were prepared, and their percolation thresholds (fc) were 1.32 and 1.43 vol %, respectively The dielectric constant of 1.40 vol % HPSi-d-Ti3C2Tx/PDMS is 23.7 at 102 Hz, which is 1.5 times that of 1.28 vol % d-Ti3C2Tx/PDMS and 8.5 times that of pure PDMS. Meanwhile, the dielectric loss of HPSi-d-Ti3C2Tx/PDMS composite is still relatively small (0.11 at 103 Hz). The origin of dielectric property optimization of the composite is attributed to the boundary capacitor model, the accumulated charges at the interfaces between the conductive filler and the insulating polymer matrix of the composite, and the distinct bimodal network structure.
Collapse
|
24
|
Design of High Temperature Complex Dielectric Properties Measuring System Based on XGBoost Algorithm. MATERIALS (BASEL, SWITZERLAND) 2020; 13:ma13061419. [PMID: 32245033 PMCID: PMC7143031 DOI: 10.3390/ma13061419] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/13/2020] [Revised: 03/05/2020] [Accepted: 03/18/2020] [Indexed: 06/11/2023]
Abstract
This paper aims to propose an online relative complex permittivity measurement system at high temperature based on microwave interferometer. A ridge waveguide with a TE10 mode was used in which the sample was heated and measured simultaneously at a frequency of 2450 MHz, and the microwave interferometer is used to collect the amplitude and phase difference of the incident signal. The Extreme Gradient Boosting (XGBoost) algorithm trained by the corresponding simulation data is used to construct the inversion model to calculate the complex dielectric coefficient of the tested material. Besides, this paper uses linear regression algorithm (LR) to calibrate the measurement system in order to improve the measurement accuracy. The entire system was tested using different materials at room temperature, and the maximum error of the measurement accuracy is less than 8% compared to the theoretical data. The robustness of the entire system was also tested by measuring Macor materials up to 800 °C. This proposed method provides an effective way to understand the mechanism between microwaves and matter at high temperatures.
Collapse
|
25
|
Hydrophobic SiC@C Nanowire Foam with Broad-Band and Mechanically Controlled Electromagnetic Wave Absorption. ACS APPLIED MATERIALS & INTERFACES 2020; 12:8555-8562. [PMID: 31985205 DOI: 10.1021/acsami.9b20636] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
With the booming of modern information technology, electromagnetic wave (EMW) absorption materials are playing more and more crucial roles in applications ranging from wearable smart electronics to national defense security. However, the application of present EMW absorption materials is severely hindered by their drawbacks, such as narrow absorption bandwidth and low absorption intensity. In this work, a series of highly porous and well-interconnected SiC@C nanowire foams (SCNFs) are rationally designed to exhibit modified impedance match and multiscale EMW energy dissipation mechanisms. The SCNF with a density of 108 mg cm-3 realizes a broad absorption bandwidth covering the whole X and Ku bands with an intensity of -52.5 dB. The SCNF with a density of 36 mg cm-3 and a thickness of 9.6 mm exhibits a mechanically controlled absorption band ranging from 2.9 to 18 GHz (covering over 93% of the entire radar band, 2-18 GHz) with a minimum intensity of -46 dB by simply applying a reversible compressive strain from 0 to 66.7%. Moreover, the special microstructure of SCNF also endows it with excellent hydrophobicity, which enables its good self-cleaning property. These encouraging achievements pave the way to the development of the continuous network microstructure of absorbents with a broad-band and tunable EMW absorption property.
Collapse
|
26
|
Energy Conversion Capacity of Barium Zirconate Titanate. MATERIALS 2020; 13:ma13020315. [PMID: 31936684 PMCID: PMC7013616 DOI: 10.3390/ma13020315] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/06/2019] [Revised: 12/29/2019] [Accepted: 01/07/2020] [Indexed: 11/17/2022]
Abstract
In this study, we investigated the effect of zirconium content on lead-free barium zirconate titanate (BZT) (Ba(ZrxTi1-x)O3, with x = 0.00, 0.01, 0.03, 0.05, and 0.08), which was prepared by the sol-gel method. A single-phase perovskite BZT was obtained under calcination and sintering conditions at 1100 C and 1300 C. Ferroelectric measurements revealed that the Curie temperature of BaTiO3 was 399 K, and the transition temperature decreased with increasing zirconium content. At the Curie temperature, Ba(Zr0.03Ti0.97)O3 with a dielectric constant of 19,600 showed the best performance in converting supplied mechanical vibration into electrical power. The experiments focused on piezoelectric activity at a low vibrating frequency, and the output power that dissipated from the BZT system at 15 Hz was 2.47 nW (30 MΩ). The prepared lead-free sol-gel BZT is promising for energy-harvesting applications considering that the normal frequencies of ambient vibration sources are less than 100 Hz.
Collapse
|
27
|
[Analysis of dielectric properties of metastatic and non-metastatic lymph nodes from lung cancer surgeries using an open-ended coaxial probe]. NAN FANG YI KE DA XUE XUE BAO = JOURNAL OF SOUTHERN MEDICAL UNIVERSITY 2019; 39:1364-1369. [PMID: 31852649 PMCID: PMC6926085 DOI: 10.12122/j.issn.1673-4254.2019.11.15] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Received: 01/03/2019] [Indexed: 11/24/2022]
Abstract
OBJECTIVE To investigate the differences in dielectric properties (relative dielectric constant and conductivity) between metastatic and non-metastatic lymph nodes (LNs). METHODS An open-end coaxial probe (1 MHz to 4 GHz) was used to measure the dielectric properties of the LNs obtained from 76 lung cancer patients. According to the results of pathological examination, the LNs were divided into metastatic and non-metastatic LNs, and the metastatic LNs were divided into lung squamous cell carcinomas and adenocarcinoma. The differences in dielectric properties of the LNs were analyzed at 1 MHz to 4 GHz and at 6 single frequencies (64, 128, 298, 433, 915, and 2450 MHz). RESULTS The metastatic LNs showed higher dielectric properties than non-metastatic LNs in the frequency range from 1 MHz to 4 GHz. No significant differences were found in the dielectric properties between metastatic LNs of lung squamous cell carcinoma and adenocarcinoma. At the 6 single frequencies, the metastatic and non-metastatic LNs showed significant differences in their dielectric properties (P < 0.01). CONCLUSIONS The open-ended coaxial probe technology is not capable of identifying the pathological type of the primary lung cancer from which the metastatic LNs are derived, but it can identify the differences in dielectric properties between metastatic and non-metastatic LNs, and thus provide a reliable means for identification of LN metastasis of lung cancer.
Collapse
|
28
|
Anisotropic Thermally Conductive Perfluoroalkoxy Composite with Low Dielectric Constant Fabricated by Aligning Boron Nitride Nanosheets via Hot Pressing. Polymers (Basel) 2019; 11:polym11101638. [PMID: 31658674 PMCID: PMC6835865 DOI: 10.3390/polym11101638] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2019] [Revised: 09/28/2019] [Accepted: 09/29/2019] [Indexed: 11/20/2022] Open
Abstract
Thermal management has become a critical challenge in electronics and portable devices. To address this issue, polymer composites with high thermal conductivity (TC) and low dielectric property are urgently needed. In this work, we fabricated perfluoroalkoxy (PFA) composite with high anisotropic TC and low dielectric constant by aligning boron nitride nanosheets (BNNs) via hot pressing. We characterized the thermal stability, microstructure, in-plane and through-plane TCs, heat dissipation capability, and dielectric property of the composites. The results indicate that the BNNs–PFA composites possessed good thermal stability. When the BNNs content was higher than 10 wt %, the BNNs were well layer aligned in the PFA matrix, and the composites showed obvious anisotropic TC. The in-plane TC and through-plane TCs of 30 wt % BNNs–PFA composite were 4.65 and 1.94 W m−1 K−1, respectively. By using the composite in thermal management of high-power LED, we found that alignment of BNNs in composite significantly improves the heat dissipation capability of composite. In addition, the composites exhibited a low dielectric property. This study shows that hot pressing is a facile and low-cost method to fabricate bulk composite with anisotropic TC, which has wide applications in electronic packaging.
Collapse
|
29
|
Synthesis, crystal structure and properties of a quaternary oxide with a new structure type, BiGaTi 4O 11. ACTA CRYSTALLOGRAPHICA SECTION C-STRUCTURAL CHEMISTRY 2019; 75:702-706. [PMID: 31166922 DOI: 10.1107/s2053229619005989] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2019] [Accepted: 04/30/2019] [Indexed: 11/10/2022]
Abstract
A new quaternary oxide, BiGaTi4O11 (bismuth gallium tetratitanium undecaoxide), was prepared by heating a mixture of the binary oxides at 1373 K in air. BiGaTi4O11 melts at 1487 K and prismatic single crystals were obtained from a sample melted at 1523 K and solidified by furnace cooling. The structure of BiGaTi4O11 was analyzed using single-crystal X-ray diffraction to be of a new type that crystallized in the space group Cmcm. A Bi3+ site is coordinated by nine O2- anions, and three oxygen-coordinated octahedral sites are statistically occupied by Ga3+ and Ti4+ cations. A relative dielectric constant of 46 with a temperature coefficient of 57 ppm K-1 in the temperature range 297-448 K was measured for a polycrystalline ceramic sample at 150 Hz-1 MHz with a dielectric loss tan δ of less than 0.01. Electrical resistivities measured at 1073 K by alternating-current impedance spectroscopic and direct-current methods were 1.16 × 10-4 and 1.14 × 10-4 S cm-1, respectively, which indicates that electrons and/or holes were conduction carriers at high temperature. The optical band gap estimated by the results of diffuse reflectance analysis was 2.9-3.0 eV, while the band gap obtained from the activation energy for electrical conduction was 3.5 eV.
Collapse
|
30
|
Dielectric Spectroscopy of Palm Olein During Batch Deep Frying and Their Relation with Degradation Parameters. J Food Sci 2019; 84:792-797. [PMID: 30861127 DOI: 10.1111/1750-3841.14436] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2018] [Revised: 12/13/2018] [Accepted: 12/15/2018] [Indexed: 11/27/2022]
Abstract
Total polar compounds (TPC) and free fatty acids (FFA) are important indicators in evaluating the quality of frying oil. Conventional methods to determine TPC and FFA are often time consuming, involved laboratory analyses which required skilled personnel and used substantial amount of harmful solvent. In this study, dielectric spectroscopy technique was used to investigate the relation between dielectric property of refined, bleached and deodorized palm olein (RBDPO) during deep frying with TPC and FFA. In total, 150 batches of French fries were intermittently fried at 185 ± 5 °C for 7 hr a day over 5 consecutive days. A total of 30 frying oil samples were collected. The dielectric property of frying oil samples were measured using impedance analyzer with frequencies ranging from 100 Hz to 10 MHz. The TPC of frying oil samples were measured with a Testo 270, while the FFA analysis was done using Malaysian Palm Oil Board (MPOB) test method. Results showed that dielectric constant, TPC and FFA of RBDPO increased as the frying time increased. Dielectric constant increased from 3.09 to 3.17, while TPC and FFA increased from 9.96 to 19.52 and from 0.08% to 0.36%, respectively. Partial least square (PLS) analysis produced good prediction of TPC and FFA with the application of genetic algorithm (GA). Model developed for prediction of TPC and FFA yielded highly significant correlation with R2 of 0.91 and 0.95, respectively and both had root mean square error in cross-validation (RMSECV) of 1.06%. This study demonstrates the potential of dielectric spectroscopy in monitoring palm olein degradation during frying. PRACTICAL APPLICATION: The application of dielectric spectroscopy to detect degradation of palm olein during frying was studied. The dielectric property of palm olein during frying has successfully correlated with TPC and FFA. The model developed in this study could be used for the development of a sensing system for palm olein degradation monitoring.
Collapse
|
31
|
An On-Line System for High Temperature Dielectric Property Measurement of Microwave-Assisted Sintering Materials. MATERIALS 2019; 12:ma12040665. [PMID: 30813380 PMCID: PMC6416583 DOI: 10.3390/ma12040665] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/17/2019] [Revised: 02/16/2019] [Accepted: 02/18/2019] [Indexed: 11/16/2022]
Abstract
Microwave-assisted sintering materials have been proven to deliver improvements in the mechanical and physicochemical properties of the materials, compared with conventional sintering methods. Accurate values of dielectric properties of materials under high temperatures are essential for microwave-assisted sintering. In view of this, this paper, proposes an on-line system to measure the high temperature dielectric properties of materials under microwave processing at a frequency of 2450 MHz. A custom-designed ridge waveguide is utilized, where samples are heated and measured simultaneously. An artificial neural network (ANN) trained with the corresponding simulation data is integrated into this system to reverse the permittivity of the measured materials. This whole system is tested at room temperature with different materials. Accuracies of measuring dielectric property with an error lower than 9% with respect to theoretical data have been achieved even for high loss media. The functionality of the dielectric measurement system has also been demonstrated by heating and measuring Macor and Duran ceramic glass samples up to 800 °C. All the preliminary experiments prove the feasibility of this system. It provides another method for dielectric property measurement and improves the understanding of the mechanism between microwave and media under high temperatures, which is helpful for optimizing the microwave-assisted sintering of materials.
Collapse
|
32
|
Effects of the Particle Size of BaTiO₃ Fillers on Fabrication and Dielectric Properties of BaTiO₃/Polymer/Al Films for Capacitor Energy-Storage Application. MATERIALS 2019; 12:ma12030439. [PMID: 30709007 PMCID: PMC6384974 DOI: 10.3390/ma12030439] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/04/2019] [Revised: 01/25/2019] [Accepted: 01/25/2019] [Indexed: 11/19/2022]
Abstract
BaTiO3/polymer/Al (BPA) composite films for energy storage were fabricated by way of a roll coating and thermal curing process. The coating slurry consisted of silicon-containing heat-resistant resin (CYN-01) and BaTiO3 particles with various particle sizes obtained from commercial BaTiO3 powders processed at different durations of wet sand grinding in the presence of silane coupling agent (KH550), which not only improves the dielectric performance of the BPA films but also facilitates its production in a large scale. The major influence factors, such as the ratio between BaTiO3 and resin and the size of BaTiO3 particles, were investigated and their related mechanisms were discussed. The results show that modifying BaTiO3 particles (D90 = 0.83 μm) with the silane coupling agent of KH550 enhances the dielectric properties of the BPA films. The typical BPA films obtained exhibit a high dielectric constant of 32, a high break strength of 20.8 V/μm and a low dielectric loss of 0.014. The present work provides a simple and convenient way to prepare high-quality ceramic/polymer composite films for energy-storage application in a large scale.
Collapse
|
33
|
Electrostatic force spectroscopy revealing the degree of reduction of individual graphene oxide sheets. BEILSTEIN JOURNAL OF NANOTECHNOLOGY 2018; 9:1146-1155. [PMID: 29719765 PMCID: PMC5905283 DOI: 10.3762/bjnano.9.106] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2017] [Accepted: 03/09/2018] [Indexed: 06/01/2023]
Abstract
Electrostatic force spectroscopy (EFS) is a method for monitoring the electrostatic force microscopy (EFM) phase with high resolution as a function of the electrical direct current bias applied either to the probe or sample. Based on the dielectric constant difference of graphene oxide (GO) sheets (reduced using various methods), EFS can be used to characterize the degree of reduction of uniformly reduced one-atom-thick GO sheets at the nanoscale. In this paper, using thermally or chemically reduced individual GO sheets on mica substrates as examples, we characterize their degree of reduction at the nanoscale using EFS. For the reduced graphene oxide (rGO) sheets with a given degree of reduction (sample n), the EFS curve is very close to a parabola within a restricted area. We found that the change in parabola opening direction (or sign the parabola opening value) indicates the onset of reduction on GO sheets. Moreover, the parabola opening value, the peak bias value (tip bias leads to the peak or valley EFM phases) and the EFM phase contrast at a certain tip bias less than the peak value can all indicate the degree of reduction of rGO samples, which is positively correlated with the dielectric constant. In addition, we gave the ranking of degree for reduction on thermally or chemically reduced GO sheets and evaluated the effects of the reducing conditions. The identification of the degree of reduction of GO sheets using EFS is important for reduction strategy optimization and mass application of GO, which is highly desired owing to its mechanical, thermal, optical and electronic applications. Furthermore, as a general and quantitative technique for evaluating the small differences in the dielectric properties of nanomaterials, the EFS technique will extend and facilitate its nanoscale electronic devices applications in the future.
Collapse
|
34
|
Improvement of Image Sticking in Liquid Crystal Display Doped with γ-Fe₂O₃ Nanoparticles. NANOMATERIALS 2017; 8:nano8010005. [PMID: 29295553 PMCID: PMC5791092 DOI: 10.3390/nano8010005] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/25/2017] [Revised: 12/12/2017] [Accepted: 12/19/2017] [Indexed: 01/23/2023]
Abstract
Image sticking in thin film transistor-liquid crystal displays (TFT-LCD) is related to the dielectric property of liquid crystal (LC) material. Low threshold value TFT LC materials have a weak stability and the free ions in them will be increased because of their own decomposition. In this study, the property of TFT LC material MAT-09-1284 doped with γ-Fe2O3 nanoparticles was investigated. The capacitances of parallel-aligned nematic LC cells and vertically aligned nematic LC cells with different doping concentrations were measured at different temperatures and frequencies. The dielectric constants perpendicular and parallel to long axis of the LC molecules ε⊥ and ε//, as well as the dielectric anisotropy Δε, were obtained. The dynamic responses and the direct current threshold voltages in parallel-aligned nematic LC cells for different doping concentrations were also measured. Although the dielectric anisotropy Δε decreased gradually with increasing temperature and frequency at the certain frequency and temperature in LC state for each concentration, the doping concentration of γ-Fe2O3 nanoparticles less than or equal to 0.145 wt % should be selected for maintaining dynamic response and decreasing free ions. This study has some guiding significance for improving the image sticking in TFT-LCD.
Collapse
|
35
|
Controllable Fabricating Dielectric-Dielectric SiC@C Core-Shell Nanowires for High-Performance Electromagnetic Wave Attenuation. ACS APPLIED MATERIALS & INTERFACES 2017; 9:40690-40696. [PMID: 29088527 DOI: 10.1021/acsami.7b13063] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
Heterostructured dielectric-dielectric nanowires of SiC core and carbon shell (SiC@C) with high-performance electromagnetic wave absorption were synthesized by combining an interfacial in situ polymer encapsulation and carbonization process. This approach overcomes the shortcomings of previous reported methods to prepare carbon shell that both carbon shell and free carbon particles are formed simultaneously. In our developed approach, the core of SiC nanowires are first positively charged. Then the negative resorcinol-formaldehyde polymers as the carbon source are anchored on SiC nanowires under the attraction of electrostatic force, which well suppresses the nucleation of free carbon particles. The thickness of the carbon shell could be modulated from 4 to 20 nm by simply adjusting the moral ratio of resorcinol to SiC nanowires. The resulting SiC@C core-shell nanostructures without free carbon particles offer synergism among the SiC nanowires and the carbon shells, generating multiple dipolar polarization, surfaced polarization, and associated relaxations, which endow SiC@C hybrid nanowires with a minimum reflection loss (RL) value of -50 dB at the frequency of 12 GHz and an effective absorption bandwidth of 8 GHz with RL value under -10 dB at the optimized state. Our results demonstrate that SiC@C hybrid nanowires are promising candidates for electromagnetic wave absorption applications.
Collapse
|
36
|
Dielectric and Carrier Transport Properties of Silicone Rubber Degraded by Gamma Irradiation. Polymers (Basel) 2017; 9:polym9100533. [PMID: 30965834 PMCID: PMC6418885 DOI: 10.3390/polym9100533] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2017] [Revised: 10/16/2017] [Accepted: 10/19/2017] [Indexed: 11/29/2022] Open
Abstract
Silicone rubber (SiR) is used as an insulating material for cables installed in a nuclear power plant. Gamma rays irradiated SiR sheets for various periods at temperatures of 145 and 185 °C, and the resultant changes were analyzed by examining complex permittivity spectra and surface potential decay characteristics. Three different processes, namely, instantaneous polarization, electrode polarization due to the accumulation of ions to form double charge layers at dielectric/electrode interfaces, and DC conduction caused by directional hopping of ions, contribute to the complex permittivity. By fitting the spectra to theoretical equations, we can obtain the dielectric constant at high frequencies, concentration and diffusion coefficient of ions and DC conductivity for the pristine and degraded samples. The instantaneous polarization becomes active with an increase of dose and ageing temperature. The thermal expansion coefficient estimated from the temperature dependence of dielectric constant at high frequencies becomes smaller with an increase in dose, which is in good agreement with the experimental results of the swelling ratio. Additionally, trap distributions are calculated from surface potential decay measurements and analyzed to explain the variation in conductivity. Trap energy increases firstly, and then decreases with an increase in dose, leading to a similar change in DC conductivity. It is concluded that generations of both oxidative products and mobile ions, as well as the occurrence of chain scission and crosslinking are simultaneously induced by gamma rays.
Collapse
|
37
|
Cellulose-Based Smart Fluids under Applied Electric Fields. MATERIALS (BASEL, SWITZERLAND) 2017; 10:E1060. [PMID: 28891966 PMCID: PMC5615715 DOI: 10.3390/ma10091060] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/10/2017] [Revised: 09/07/2017] [Accepted: 09/08/2017] [Indexed: 11/17/2022]
Abstract
Cellulose particles, their derivatives and composites have special environmentally benign features and are abundant in nature with their various applications. This review paper introduces the essential properties of several types of cellulose and their derivatives obtained from various source materials, and their use in electro-responsive electrorheological (ER) suspensions, which are smart fluid systems that are actively responsive under applied electric fields, while, at zero electric field, ER fluids retain a liquid-like state. Given the actively controllable characteristics of cellulose-based smart ER fluids under an applied electric field regarding their rheological and dielectric properties, they can potentially be applied for various industrial devices including dampers and haptic devices.
Collapse
|
38
|
Building a Novel Chemically Modified Polyaniline/Thermally Reduced Graphene Oxide Hybrid through π-π Interaction for Fabricating Acrylic Resin Elastomer-Based Composites with Enhanced Dielectric Property. ACS APPLIED MATERIALS & INTERFACES 2017; 9:28887-28901. [PMID: 28776970 DOI: 10.1021/acsami.7b07785] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Sustainability urgently demands low dielectric loss and low elastic modulus as fostering high permittivity (Hi-K) conductor/polymer composites. This work introduces a ternary composite system, consisting of acrylic resin elastomer (AR), chemically modified polyaniline (HBSiPA), and the thermally reduced graphene oxides (TrGOs), for applying to actuators, of which AR was fabricated by free radical polymerization. The unique hybridized graphene (HBSiPA-TrGO) was prepared by a two-step procedure, including the doped polyaniline modified by the hyperbranched polysiloxane via a ring opening reaction, followed by the decoration of HBSiPA on the surface of TrGO, the conductivity of which is desired to be the same as that of graphene. Afterward, diverse filler contents of HBSiPA-TrGO were put into the AR matrix to fabricate composites with the solution casting method and TrGO/AR composites were fabricated as well for comparison. Unlike TrGO, HBSiPA has plenty of polyaniline chain segments that ensure better dispersion of graphene hybrids in the AR, and thus the composites inherit the excellent electrical property of graphene. The permittivity and dielectric loss of the HBSiPA-TrGO/AR composite at 100 Hz are 3.5 and 0.27 times that of the TrGO/AR composite, respectively, when the loading of fillers approaches the percolation threshold (fc), which originates from the HBSiPA anchored onto the graphene serving as spacer and thus decreases the leakage currents induced by the contact of graphene sheets. Besides, the elastic modulus of 2.83 vol % HBSiPA-TrGO/AR composite was lower than 5 MPa.
Collapse
|
39
|
Facile Synthesis and Hierarchical Assembly of Flowerlike NiO Structures with Enhanced Dielectric and Microwave Absorption Properties. ACS APPLIED MATERIALS & INTERFACES 2017; 9:16404-16416. [PMID: 28459536 DOI: 10.1021/acsami.7b02597] [Citation(s) in RCA: 69] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
In this work, two novel flowerlike NiO hierarchical structures, rose-flower (S1) and silk-flower (S2), were synthesized by using a facial hydrothermal method, coupled with subsequent postannealing process. Structures, morphologies, and magnetic and electromagnetic properties of two NiO structures have been systematically investigated. SEM and TEM results suggested that S1 had a hierarchical rose-flower architecture with diameters in the range of 4-7 μm, whereas S2 exhibited a porous silk-flower architecture with diameters of 0.7-1.0 μm. Electromagnetic performances indicated that the NiO hierarchical structures played a crucial role in determining their dielectric behavior and impedance matching characteristic, which further influenced the microwave attenuation property of absorbers based on them. Due to its hierarchical and porous architectures, S2 had higher microwave absorption performances than S1. The maximum RL value for sample S2 can reach -65.1 dB at 13.9 GHz, while an efficient bandwidth of 3 GHz was obtained. In addition, the mechanism of the improved microwave absorption were discussed in detail. It is expected that our NiO hierarchical structures synthesized in this work could be used as a reference to design novel microwave absorption materials.
Collapse
|
40
|
Bilayer Polymer Metacomposites Containing Negative Permittivity Layer for New High-k Materials. ACS APPLIED MATERIALS & INTERFACES 2017; 9:1793-1800. [PMID: 28005330 DOI: 10.1021/acsami.6b12786] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Polymer matrix high-k composites are of considerable interest in various electronic devices, such as capacitors, antennas, actuators, etc. However, how to enhance the permittivity without elevating the loss remains a challenge for us. Here we present a novel design of bilayer high-k metacomposites consisting of two stacked single layers with positive permittivity and negative permittivity. Interestingly, the bilayer system shows an obvious permittivity boost effect with a permittivity improved by a 40-fold increase compared with the polymer matrix, while maintaining a loss tangent as low as 0.06. Further calculation results indicate that the permittivity of the bilayer composites could be enhanced by 4000-fold or even a greater increase as compared with the polymer matrix via balancing the dielectric properties of single layers. Insights into how the thickness ratios and dielectric properties of single layers interfere with the dielectric performances of bilayer composites were discussed. This study provides a new route for the design of high-k materials, and it will have great significance on the development of dielectric materials. Hopefully, multilayer high-k metacomposites with fascinating dielectric performances could be achieved via balancing the dielectric properties of single layers.
Collapse
|
41
|
Dielectric properties of brain tissue at 1 GHz in acute ischemic stroke: Experimental study on swine. Bioelectromagnetics 2016; 38:158-163. [PMID: 27901288 DOI: 10.1002/bem.22024] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2016] [Accepted: 11/02/2016] [Indexed: 11/10/2022]
|
42
|
Preparation of a Carbon Doped Tissue-Mimicking Material with High Dielectric Properties for Microwave Imaging Application. MATERIALS 2016; 9:ma9070559. [PMID: 28773678 PMCID: PMC5456944 DOI: 10.3390/ma9070559] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/30/2016] [Revised: 07/06/2016] [Accepted: 07/07/2016] [Indexed: 11/16/2022]
Abstract
In this paper, the oil-in-gelatin based tissue-mimicking materials (TMMs) doped with carbon based materials including carbon nanotube, graphene ink or lignin were prepared. The volume percent for gelatin based mixtures and oil based mixtures were both around 50%, and the doping amounts were 2 wt %, 4 wt %, and 6 wt %. The effect of doping material and amount on the microwave dielectric properties including dielectric constant and conductivity were investigated over an ultra-wide frequency range from 2 GHz to 20 GHz. The coaxial open-ended reflection technology was used to evaluate the microwave dielectric properties. Six measured values in different locations of each sample were averaged and the standard deviations of all the measured dielectric properties, including dielectric constant and conductivity, were less than one, indicating a good uniformity of the prepared samples. Without doping, the dielectric constant was equal to 23 ± 2 approximately. Results showed with doping of carbon based materials that the dielectric constant and conductivity both increased about 5% to 20%, and the increment was dependent on the doping amount. By proper selection of doping amount of the carbon based materials, the prepared material could map the required dielectric properties of special tissues. The proposed materials were suitable for the phantom used in the microwave medical imaging system.
Collapse
|
43
|
High Dielectric Performance of Polyamide 66/Poly(Vinylidene Fluoride) Flexible Blends Induced by Interfacial Copolymer for Capacitors. Polymers (Basel) 2015; 8:E2. [PMID: 30979100 PMCID: PMC6432524 DOI: 10.3390/polym8010002] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2015] [Revised: 12/11/2015] [Accepted: 12/22/2015] [Indexed: 11/28/2022] Open
Abstract
The copolymer VAMA was synthesized from vinyl acetic and maleic anhydride. A new all-polymeric blend with a high dielectric constant (ε) has been developed by blending polyvinylidene fluoride (PVDF) with vinyl acetic-maleic anhydride modified polyamide (PA66-g-VM). The blend shows high dielectric constants (εblend = 20) and excellent mechanical properties. The SEM investigations suggest that the enhanced dielectric behavior originates from significant interfacial interactions between polymers. The XRD demonstrates that the compatibilizer affects the crystalline behavior of each component. Furthermore, the stable dielectric constants of the all-polymeric blends can be tuned by adjusting the content of the compatibilizer. The created high-ε all-polymeric blends represent a novel type of material that is technologically simple, easy to process, and of a relatively high dielectric constant, with application for flexible electronics.
Collapse
|
44
|
Dielectric Properties of Dual-Frequency Reactive Mesogens before and after Photopolymerization. MATERIALS 2014; 7:1113-1121. [PMID: 28788503 PMCID: PMC5453106 DOI: 10.3390/ma7021113] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/30/2013] [Revised: 01/27/2014] [Accepted: 02/07/2014] [Indexed: 11/16/2022]
Abstract
The dielectric properties of reactive mesogens before and after photopolymerization were investigated. Commercially available nematic reactive mesogens (RMS03-013C, Merck) were measured and found to be dual-frequency liquid crystals. The property arose from the δ-relaxation process that was caused by rotational fluctuations parallel to the molecule’s long axis. After polymerization, the polymerized reactive mesogens still exhibited this dual-frequency property. The result was attributed to the β-relaxation process which arose from rotational fluctuations of localized parts of the main chain. The sign change of the dielectric anisotropy with increasing frequency after polymerization was opposite to the sign change before polymerization.
Collapse
|
45
|
Flexible nanodielectric materials with high permittivity for power energy storage. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2013; 25:6334-6365. [PMID: 24038139 DOI: 10.1002/adma.201301752] [Citation(s) in RCA: 353] [Impact Index Per Article: 32.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/19/2013] [Indexed: 06/02/2023]
Abstract
Study of flexible nanodielectric materials (FNDMs) with high permittivity is one of the most active academic research areas in advanced functional materials. FNDMs with excellent dielectric properties are demonstrated to show great promise as energy-storage dielectric layers in high-performance capacitors. These materials, in common, consist of nanoscale particles dispersed into a flexible polymer matrix so that both the physical/chemical characteristics of the nanoparticles and the interaction between the nanoparticles and the polymers have crucial effects on the microstructures and final properties. This review first outlines the crucial issues in the nanodielectric field and then focuses on recent remarkable research developments in the fabrication of FNDMs with special constitutents, molecular structures, and microstructures. Possible reasons for several persistent issues are analyzed and the general strategies to realize FNDMs with excellent integral properties are summarized. The review further highlights some exciting examples of these FNDMs for power-energy-storage applications.
Collapse
|
46
|
Thickness Dependent Characteristics of High Permittivity PMN-0.32PT Single Crystal for High Frequency Medical Imaging Applications. FERROELECTRICS 2011; 422:70-76. [PMID: 22162876 PMCID: PMC3232676 DOI: 10.1080/00150193.2011.594707] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
The dielectric, piezoelectric, and acoustic properties of PMN-0.32PT (Pb(Mg(1/3)Nb(2/3)) O(3)-PbTiO(3)) single crystals were investigated as a function of sample thickness ranging from 120 to 30 μm in order to enlighten the origin of property degradation of crystals for high frequency ultrasound applications. Electromechanical coupling factor(k(t) ), clamped and free dielectric constants decreased but sound velocity increased with decreasing crystal thickness. Particularly, repoling of the PMN-PT crystals would bring about a noteworthy enhancement in electromechanical and dielectric properties, which urges the importance of PMN-PT as a promising piezoelectric material for high frequency ultrasound transducers.
Collapse
|