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Sakhraoui T, Karlický F. Prediction of induced magnetism in 2D Ti 2C based MXenes by manipulating the mixed surface functionalization and metal substitution computed by xTB model Hamiltonian of the DFTB method. Phys Chem Chem Phys 2024; 26:12862-12868. [PMID: 38623885 DOI: 10.1039/d3cp05665a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/17/2024]
Abstract
We employed the recently developed density functional tight binding (DFTB) method's Hamiltonian, GFN1-xTB, for modeling the mixed termination in Ti2C MXenes, namely three types of termination by combining -O and -OH, -O and -F, and -F and -OH. We demonstrated that the approach yields reliable predictions for the electronic and magnetic properties of such MXenes. The first highlighted result is that the mixed surface functionalization in Ti2CAxBy MXenes induces spin polarization with diverse magnetic alignments, including ferromagnetism and two types of antiferromagnetism. We further identified the magnetic alignment for the investigated MXene in terms of the compositions of the terminal groups. Moreover, the effect of the transition metal (Ti) substituted by the Sc atom on the electronic and magnetic properties was also investigated. We found that the studied systems maintain the magnetism and the metallic characteristics. A magnetic transition from antiferromagnetic (AFM) to ferrimagnetic (FiM) ordering was found for ScTi15C8F8(OH)8 and ScTi15C8F12(OH)4 compounds. Finally, we proved that incorporating the Sc atom into the lattice of Ti2CO2 and the mixed surface termination in Ti2CAxBy is an effective strategy to induce magnetism. Our study may provide a new potential application for designing MXene-based spintronics.
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Affiliation(s)
- Taoufik Sakhraoui
- Department of Physics, Faculty of Science, University of Ostrava, 701 03 Ostrava, Czech Republic.
| | - František Karlický
- Department of Physics, Faculty of Science, University of Ostrava, 701 03 Ostrava, Czech Republic.
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2
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Fabris GSL, Galvão DS, Paupitz R. Reversible actuation of α-borophene nanoscrolls. Phys Chem Chem Phys 2024; 26:11589-11596. [PMID: 38533829 DOI: 10.1039/d3cp06193k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/28/2024]
Abstract
In this work, we proposed and investigated the structural and electronic properties of boron-based nanoscrolls (armchair and zigzag) using the DFTB+ method. We also investigated the electroactuation process (injecting and removing charges). A giant electroactuation was observed, but the results show relevant differences between the borophene and carbon nanoscrolls. The molecular dynamics simulations showed that the scrolls are thermally and structurally stable for a large range of temperatures (up to 600 K), and the electroactuation process can be easily tuned and can be entirely reversible for some configurations.
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Affiliation(s)
- Guilherme S L Fabris
- Postgraduate Program in Materials Science and Engineering, Federal University of Pelotas, 96010-610, Pelotas, RS, Brazil
| | - Douglas S Galvão
- Applied Physics Department, State University of Campinas, 13083-970, Campinas, SP, Brazil
| | - Ricardo Paupitz
- Physics Department, Sao Paulo State University - UNESP, CEP-13506-900 Rio Claro, SP, Brazil.
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3
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Leamer JM, Dawson W, Bondar DI. Positivity preserving density matrix minimization at finite temperatures via square root. J Chem Phys 2024; 160:074107. [PMID: 38375902 DOI: 10.1063/5.0189864] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2023] [Accepted: 01/18/2024] [Indexed: 02/21/2024] Open
Abstract
We present a Wave Operator Minimization (WOM) method for calculating the Fermi-Dirac density matrix for electronic structure problems at finite temperature while preserving physicality by construction using the wave operator, i.e., the square root of the density matrix. WOM models cooling a state initially at infinite temperature down to the desired finite temperature. We consider both the grand canonical (constant chemical potential) and canonical (constant number of electrons) ensembles. Additionally, we show that the number of steps required for convergence is independent of the number of atoms in the system. We hope that the discussion and results presented in this article reinvigorate interest in density matrix minimization methods.
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Affiliation(s)
- Jacob M Leamer
- Department of Physics and Engineering Physics, Tulane University, 6823 St. Charles Ave., New Orleans, Louisiana 70118, USA
| | - William Dawson
- RIKEN Center for Computational Science, Kobe, Hyogo 650-0047, Japan
| | - Denys I Bondar
- Department of Physics and Engineering Physics, Tulane University, 6823 St. Charles Ave., New Orleans, Louisiana 70118, USA
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Sakhraoui T. Effect of vacancy defect and strain on the structural, electronic and magnetic properties of carbon nitride 2D monolayers by DFTB method. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2023; 35. [PMID: 37183456 DOI: 10.1088/1361-648x/acd293] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/05/2022] [Accepted: 05/04/2023] [Indexed: 05/16/2023]
Abstract
We investigate the electronic and magnetic properties of CnNm(C6N6, C2N, C3N and C3N4) using density functional tight-binding (DFTB) method. We find that these compounds are dynamically stable and their electronic band gaps are in the range of 0.59-3.28 eV. We show that the electronic structure is modulated by strain and the semiconducting behavior is well preserved except for C3N at +5% biaxial strain, where a transition from semiconductor to metal was observed. Under +3% biaxial strain, C3N4undergoes a transition from an indirect (K-Γ) to a direct (Γ-Γ) band gap. Moreover, band gap of C2N transforms from direct (Γ-Γ) to indirect (M-Γ) under +4% biaxial strain. However, no change in the nature of the band gap of C6N6. Further, when the studied materials under uniaxial tensile strain, their bandgaps reduce. Our theoretical study showed that an indirect-to-direct nature transition may occur for C6N6and for C3N4, which broadens their applications. On the other hand, magnetism is observed in all N-vacancy defected CnNm, which encourages its application in spintronic. Moreover, calculations of formation energies indicate that N-vacancy is energetically more favorable than C-vacancy in both C2N and C3N4. Opposite behavior found for C6N6and C3N.
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Affiliation(s)
- Taoufik Sakhraoui
- Department of Physics, Faculty of Science, University of Ostrava, 30. Dubna 22, 701 03 Ostrava, Czech Republic
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Xing X, Wei J, Xu W, Wang B, Luo S, Yu Q. Effect of Organic Polymers on Mechanical Property and Toughening Mechanism of Slag Geopolymer Matrix. Polymers (Basel) 2022; 14:polym14194214. [PMID: 36236162 PMCID: PMC9573140 DOI: 10.3390/polym14194214] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2022] [Revised: 09/30/2022] [Accepted: 10/03/2022] [Indexed: 11/05/2022] Open
Abstract
In this work, two series of chemically reactive polymers, silane coupling agents (SCAs) and water-soluble polymers, were specifically designed as an additive to improve the ductility of slag geopolymer paste by vibration pressure technique. The influences of organic polymers on the fluidity, rheological behavior, mechanical property, porosity, and toughening mechanism of slag geopolymer were investigated. The polycondensation and bonding characteristics of organic-inorganic products were calculated by 1H liquid nuclear magnetic resonance (NMR) technology and Fourier transform infrared (FT-IR). The polymerization degree of composite geopolymer was evaluated by 29Si NMR and X-ray photoelectron spectroscopy (XPS). The microscopic morphology of the geopolymer matrix was analyzed using scanning electron microscopy (SEM). The results showed that the dosage of the KH570 and PAA-Na with 5 wt% behaved best in improving the flexural strength and the compressive strength of geopolymer in their corresponding organic series, respectively. The addition of polymers decreased the fluidity and the fluidity loss ratio of geopolymer slurry but reduced the harmful pores of hardened geopolymer. The organic polymers acting as bridge-fixed water molecules weakened the repulsion force, and formed a three-dimensional network through molecular interweaving in a geopolymer matrix. Methacryloxy in silane coupling agents and carboxyl group in water-soluble polymers may contribute to the improvement of hydration product structure through strong bonding with C-A-S-H. Microscopic measurements indicated that the addition of KH570 and PAA-Na in geopolymer could form 73.55% and 72.48% Si-O-Si with C-A-S-H gel, higher than the reference, and increase the polycondensation degree of C-A-S-H phase, reflected by the increased generation of Q2 and Q2(1Al) and the longer chain length, leading to a higher densified geopolymer matrix with high ductility.
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Dynamic diffusion and precipitation processes across calcium silicate membranes. J Colloid Interface Sci 2022; 618:206-218. [PMID: 35338927 DOI: 10.1016/j.jcis.2022.03.042] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2021] [Revised: 02/15/2022] [Accepted: 03/09/2022] [Indexed: 11/24/2022]
Abstract
HYPOTHESIS Chemical gardens are tubular inorganic structures exhibiting complex morphologies and interesting dynamic properties upon ageing, with coupled diffusion and precipitation processes keeping the systems out of equilibrium for extended periods of time. Calcium-based silica gardens should comprise membranes that mimic the microstructures occurring in ordinary Portland cement and/or silicate gel layers observed around highly reactive siliceous aggregates in concrete. EXPERIMENTS Single macroscopic silica garden tubes were prepared using pellets of calcium chloride and sodium silicate solution. The composition of the mineralized tubes was characterized by means of various ex-situ techniques, while time-dependent monitoring of the solutions enclosed by and surrounding the membrane gives insight into the spatiotemporal distribution of the different ionic species. The latter data reflect transport properties and precipitation reactions in the system, thus allowing its complex dynamic behavior to be resolved. FINDINGS The results show that in contrast to the previously studied cases of iron- and cobalt-based silica gardens, the formed calcium silicate membrane is homogeneous and ultimately becomes impermeable to all species except water, hydroxide and sodium ions, resulting in the permanent conservation of considerable concentration gradients across the membrane. The insights gained in this work may help elucidate the nature and mechanisms of ion diffusion in Portland cements and concrete, especially those occurring during initial hydration of calcium silicates and the so-called alkali-silica reaction (ASR), one of the major concrete deterioration mechanisms causing serious problems with respect to the durability of concrete and the restricted use of many potential sources of raw materials.
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Sakhraoui T, Karlický F. DFTB investigations of the electronic and magnetic properties of fluorographene with vacancies and with adsorbed chemical groups. Phys Chem Chem Phys 2022; 24:3312-3321. [PMID: 35050289 DOI: 10.1039/d1cp00995h] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The electronic and magnetic properties of fluorographene (CF) in the presence of F-vacancy defects and/or chemical groups (-OH, -CN, or -NH2) were computationally investigated within the framework of the density functional tight-binding (DFTB) method. The current method parameterization allowed us to perform accurate electronic structure calculations (at the ab initio level of many-body methods in the particular case of CF) for hundreds of atoms in the computational cell. We show that the F-vacancy and/or chemical groups influence the magnetic structure, which depends on the number of defects and their distribution between the two sides of the graphene plane. Interestingly, we pointed out a possibility of imprinting local magnetism not only via F-vacancy and -OH combinations, but also using F-vacancies and -CN or -NH2 groups. In such structures, the magnetic ordering and the total magnetic moments depend on their adsorption sites and their presence in the same or on opposite sides of the graphene plane. We devote particular attention to the interacting chemical group with the F-vacancies. The interaction between the adsorbed chemical group and the unpaired spins associated with the F-vacancies in CF gives rise to interesting magnetic structures. Finally, the zigzag-like direction is shown as the most preferred for the defluorination of CF. Stable ferrimagnetic zigzag chains with interesting properties are considered to be basic magnetic features in perturbed CF. Our work provides new guidelines for engineering multifunctional spintronic components using CF as a base material. We believe, in particular, that the magnetism is predominantly controlled by the F-vacancies, and the ferromagnet can ideally be regulated via the adsorption of a chemical group on a defective CF supercell.
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Affiliation(s)
- Taoufik Sakhraoui
- Department of Physics, Faculty of Science, University of Ostrava, 701 03 Ostrava, Czech Republic.
| | - František Karlický
- Department of Physics, Faculty of Science, University of Ostrava, 701 03 Ostrava, Czech Republic.
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Paupitz R, da Silva TJ, Caldas MJ, Galvão DS, Fonseca AF. Auxetic properties of a newly proposed γ-graphyne-like material. Chem Phys Lett 2022. [DOI: 10.1016/j.cplett.2021.139220] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Ghazanlou SI, Ghazanlou SI, Ashraf W. Improvement in the physical and mechanical properties of the cement-based composite with the addition of nanostructured BN-Fe 3O 4 reinforcement. Sci Rep 2021; 11:19358. [PMID: 34588531 PMCID: PMC8481330 DOI: 10.1038/s41598-021-98800-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2021] [Accepted: 09/08/2021] [Indexed: 11/09/2022] Open
Abstract
In this work, the performance of modified cement by nanostructures consisting of boron nitride (BN) and iron oxide inorganic nanoparticles (Fe3O4) was analyzed. The mechanical strength, electrical resistivity, and the degree of cement hydration as well as the microstructure were investigated in detail. A hybrid filler boron nitride-iron oxide (BN-F) composed of Fe3O4 and BN was successfully synthesized using a chemical reaction. Transmission electron microscope (TEM) results showed proper binding of BN-F nanostructures. Addition of the hybrid nanostructured BN-F5 (containing 0.5 wt.% Fe3O4 and 0.5 wt.% BN) into the cement matrix increased the compressive strength and flexural strength by 65%, and 74%, respectively, after 28 days of curing. The improvement in mechanical strength is attributed to the increased surface friction induced by the Fe3O4 nanoparticles on the BN surfaces, resulting in increased interaction with the matrix. Microstructural studies, such as scanning electron microscope (SEM), showed the formation of a dense structure due to improved dispersion in the cement environment and hybrid performance in preventing crack growth, which is the main reason for the overall improvement in mechanical properties. The concrete resistance gauge (RCON, Giatec) and simultaneous thermal analysis (STA) tests revealed a significant increase in thermal and electrical conductivity in composite reinforced with nanostructured BN-F.
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Affiliation(s)
- Siavash Imanian Ghazanlou
- Faculty of Materials Engineering, Sahand University of Technology, P.O. Box 51335-1996, Tabriz, Iran.
| | - Siamak Imanian Ghazanlou
- Nanotechnology Department, School of Advanced Technologies, Iran University of Science and Technology (IUST), 16846-13114, Narmak, Tehran, Iran
| | - Warda Ashraf
- Department of Civil Engineering, Center for Advanced Construction Materials (CACM), University of Texas at Arlington, Nedderman Hall, Arlington, TX, 76010, USA
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Interactions between Reduced Graphene Oxide with Monomers of (Calcium) Silicate Hydrates: A First-Principles Study. NANOMATERIALS 2021; 11:nano11092248. [PMID: 34578564 PMCID: PMC8466668 DOI: 10.3390/nano11092248] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/27/2021] [Revised: 08/23/2021] [Accepted: 08/26/2021] [Indexed: 12/13/2022]
Abstract
Graphene is a two-dimensional material, with exceptional mechanical, electrical, and thermal properties. Graphene-based materials are, therefore, excellent candidates for use in nanocomposites. We investigated reduced graphene oxide (rGO), which is produced easily by oxidizing and exfoliating graphite in calcium silicate hydrate (CSHs) composites, for use in cementitious materials. The density functional theory was used to study the binding of moieties, on the rGO surface (e.g., hydroxyl-OH/rGO and epoxide/rGO groups), to CSH units, such as silicate tetrahedra, calcium ions, and OH groups. The simulations indicate complex interactions between OH/rGO and silicate tetrahedra, involving condensation reactions and selective repairing of the rGO lattice to reform pristine graphene. The condensation reactions even occurred in the presence of calcium ions and hydroxyl groups. In contrast, rGO/CSH interactions remained close to the initial structural models of the epoxy rGO surface. The simulations indicate that specific CSHs, containing rGO with different interfacial topologies, can be manufactured using coatings of either epoxide or hydroxyl groups. The results fill a knowledge gap, by establishing a connection between the chemical compositions of CSH units and rGO, and confirm that a wet chemical method can be used to produce pristine graphene by removing hydroxyl defects from rGO.
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Tareen N, Kim J, Kim WK, Park S. Fuzzy Logic-Based and Nondestructive Concrete Strength Evaluation Using Modified Carbon Nanotubes as a Hybrid PZT-CNT Sensor. MATERIALS 2021; 14:ma14112953. [PMID: 34070776 PMCID: PMC8198687 DOI: 10.3390/ma14112953] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/06/2021] [Revised: 05/02/2021] [Accepted: 05/05/2021] [Indexed: 11/16/2022]
Abstract
Concrete strength and factors affecting its development during early concrete curing are important research topics. Avoiding uncertain incidents during construction and in service life of structures requires an appropriate monitoring system. Therefore, numerous techniques are used to monitor the health of a structure. This paper presents a nondestructive testing technique for monitoring the strength development of concrete at early curing ages. Dispersed carbon nanotubes (CNTs) were used with cementitious materials and piezoelectric (PZT) material, a PZT ceramic, owing to their properties of intra electromechanical effects and sensitivity to measure the electromechanical impedance (EMI) signatures and relevant properties related to concrete strength, such as the elastic modulus, displacement, acceleration, strength, and loading effects. Concrete compressive strength, hydration temperature, mixture ratio, and variation in data obtained from the impedance signatures using fuzzy logic were utilized in the comparative result prediction method for concrete strength. These results were calculated using a fuzzy logic-based model considering the maturity method, universal testing machine (UTM) data, and analyzed EMI data. In the study, for data acquisition, a hybrid PZT-CNT sensor and a temperature sensor (Smart Rock) were embedded in the concrete to obtain the hydration temperature history to utilize the concrete maturity method and provide data on the EMI signatures. The dynamic changes in the medium caused during the phase in the concrete strengthening process were analyzed to predict the strength development process of concrete at early curing ages. Because different parameters are considered while calculating the concrete strength, which is related to its mechanical properties, the proposed novel method considers that changes in the boundary condition occurring in the concrete paste modify the resonant frequency response of the structure. Thus, relating and analyzing this feature can help predict the concrete strength. A comprehensive comparison of the results calculated using the proposed module, maturity method, and cylindrical specimens tested using the UTM proved that it is a cost-effective and fast technique to estimate concrete strength to ensure a safe construction of reinforced cement concrete infrastructures.
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Affiliation(s)
- Najeebullah Tareen
- Department of Civil, Architectural & Environmental System Engineering, Sungkyunkwan University, 2066 Seobu-ro, Suwon-si 16419, Korea;
| | - Junkyeong Kim
- Safety Inspection for Infrastructure Laboratory (SIIL), Advanced Institute of Convergence Technology (AICT), Suwon-si 16229, Korea;
| | - Won-Kyu Kim
- Department of Convergence Engineering for Future City, Sungkyunkwan University, 2066 Seobu-ro, Suwon-si 16419, Korea;
| | - Seunghee Park
- School of Civil, Architectural Engineering and Landscape Architecture, Sungkyunkwan University, 2066 Seobu-ro, Suwon-si 16419, Korea
- Correspondence: ; Tel.: +82-31-290-7525
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Wang F, Du Y, Jiao D, Zhang J, Zhang Y, Liu Z, Zhang Z. Wood-Inspired Cement with High Strength and Multifunctionality. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2021; 8:2000096. [PMID: 33552847 PMCID: PMC7856898 DOI: 10.1002/advs.202000096] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/08/2020] [Revised: 09/23/2020] [Indexed: 05/29/2023]
Abstract
Taking lessons from nature offers an increasing promise toward improved performance in man-made materials. Here new cement materials with unidirectionally porous architectures are developed by replicating the designs of natural wood using a simplified ice-templating technique in light of the retention of ice-templated architectures by utilizing the self-hardening nature of cement. The wood-like cement exhibits higher strengths at equal densities than other porous cement-based materials along with unique multifunctional properties, including effective thermal insulation at the transverse profile, controllable water permeability along the vertical direction, and the easy adjustment to be water repulsive by hydrophobic treatment. The strengths are quantitatively interpreted by discerning the effects of differing types of pores using an equivalent element approach. The simultaneous achievement of high strength and multifunctionality makes the wood-like cement promising for applications as new building materials, and verifies the effectiveness of wood-mimetic designs in creating new high-performance materials. The simple fabrication procedure by omitting the freeze-drying treatment can also promote a better efficiency of ice-templating technique for the mass production in engineering and may be extended to other material systems.
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Affiliation(s)
- Faheng Wang
- Shi‐Changxu Innovation Center for Advanced MaterialsInstitute of Metal ResearchChinese Academy of SciencesShenyang110016China
- Nano Science and Technology InstituteUniversity of Science and Technology of ChinaSuzhou215123China
- Jihua LaboratoryFoshan528200China
| | - Yuanbo Du
- School of Transportation Science and EngineeringHarbin Institute of TechnologyHarbin150090China
| | - Da Jiao
- Shi‐Changxu Innovation Center for Advanced MaterialsInstitute of Metal ResearchChinese Academy of SciencesShenyang110016China
| | - Jian Zhang
- Shi‐Changxu Innovation Center for Advanced MaterialsInstitute of Metal ResearchChinese Academy of SciencesShenyang110016China
| | - Yuan Zhang
- Shi‐Changxu Innovation Center for Advanced MaterialsInstitute of Metal ResearchChinese Academy of SciencesShenyang110016China
| | - Zengqian Liu
- Shi‐Changxu Innovation Center for Advanced MaterialsInstitute of Metal ResearchChinese Academy of SciencesShenyang110016China
- School of Materials Science and EngineeringUniversity of Science and Technology of ChinaHefei230026China
| | - Zhefeng Zhang
- Shi‐Changxu Innovation Center for Advanced MaterialsInstitute of Metal ResearchChinese Academy of SciencesShenyang110016China
- School of Materials Science and EngineeringUniversity of Science and Technology of ChinaHefei230026China
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Pan H, She W, Zuo W, Zhou Y, Huang J, Zhang Z, Geng Z, Yao Y, Zhang W, Zheng L, Miao C, Liu J. Hierarchical Toughening of a Biomimetic Bulk Cement Composite. ACS APPLIED MATERIALS & INTERFACES 2020; 12:53297-53309. [PMID: 33169963 DOI: 10.1021/acsami.0c15313] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Because of the inherent quasibrittleness and heterogeneity, matrix-directed toughening of concrete and cement composites remains to be a huge challenge. Herein, inspired by nacre materials, a novel biomimetic bulk cement composite is fabricated via a facile and efficient process based on compacting prefabricated multisized cement-polymer hybrid prills. This method combines with the three-dimensional "brick-bridge-mortar" structure design and synchronously the intrinsic and extrinsic toughening strategies. Such an approach shows the remarkable maximum toughness enhancement of 27-fold with 71% increase in flexural strength via cooperation with only 4 wt % organic matter. More attractively, it alters the traditional brittle fracture of cement composites to a distinct ductile fracture. In addition, such a biomimetic composite demonstrates the long-term ever-increasing strength and toughness, performing the excellent ductile-fracture retention ability. The hierarchical toughening mechanisms are further revealed with the synergy of microscopic characterizations and simulation methods. This strategy provides a new route for the development of high toughness biomimetic cement-based materials for potential applications in civil engineering domain.
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Affiliation(s)
- Hao Pan
- Jiangsu Key Laboratory of Construction Materials, School of Materials Science and Engineering, Southeast University, Nanjing 211189, China
| | - Wei She
- Jiangsu Key Laboratory of Construction Materials, School of Materials Science and Engineering, Southeast University, Nanjing 211189, China
| | - Wenqiang Zuo
- Laboratoire Navier, IFSTTAR / CNRS / ENPC, Université Gaustave Eiffel, Champs-sur-Marne 77420, France
| | - Yang Zhou
- Jiangsu Key Laboratory of Construction Materials, School of Materials Science and Engineering, Southeast University, Nanjing 211189, China
| | - Jiale Huang
- Jiangsu Key Laboratory of Construction Materials, School of Materials Science and Engineering, Southeast University, Nanjing 211189, China
| | - Zhongwen Zhang
- School of Civil Engineering, Southeast University, Nanjing 211189, China
| | - Zifan Geng
- Jiangsu Key Laboratory of Construction Materials, School of Materials Science and Engineering, Southeast University, Nanjing 211189, China
| | - Yiming Yao
- School of Civil Engineering, Southeast University, Nanjing 211189, China
| | - Wenhua Zhang
- College of Civil Engineering, Nanjing Forestry University, Nanjing 210037, China
| | - Li Zheng
- School of Science and Engineering, University of Dundee, Dundee DD1 4HN, U.K
| | - Changwen Miao
- Jiangsu Key Laboratory of Construction Materials, School of Materials Science and Engineering, Southeast University, Nanjing 211189, China
| | - Jiaping Liu
- Jiangsu Key Laboratory of Construction Materials, School of Materials Science and Engineering, Southeast University, Nanjing 211189, China
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Villegas-Lelovsky L, Paupitz R. Graphenylene-based nanoribbons for novel molecular electronic devices. Phys Chem Chem Phys 2020; 22:28365-28375. [PMID: 33300921 DOI: 10.1039/d0cp04188b] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
In the last decade, graphene has been frequently cited as one of the most promising materials for nanoelectronics. However, despite its outstanding mechanical and electronic properties, its use in the production of real nanoelectronic devices usually imposes some practical difficulties. This happens mainly due to the fact that, in its pristine form, graphene is a gapless material. We investigate theoretically the possibility of obtaining rectifying nanodevices using another carbon based two dimensional material, namely the graphenylene. This material has the advantage of being an intrinsic semiconductor, posing as a promising material for nanoelectronics. By doping graphenylene, one could obtain 2-dimensional p-n junctions, which can be useful for the construction of low dimensional electronic devices. We propose 2-dimensional diodes in which a clear rectification effect was demonstrated, with a conducting threshold of approximately 1.5 eV in direct bias and current blocking with opposite bias. During these investigations were found specific configurations that could result in devices with Zener-like behavior. Also, one unexpected effect was identified, which was the existence of transmission dips in electronic conductance plots. This result is discussed as a related feature to what was found in graphene nanoribbon systems under external magnetic fields, even though the external field was not a necessary ingredient to obtain such effect in the present case.
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Krystek M, Pakulski D, Patroniak V, Górski M, Szojda L, Ciesielski A, Samorì P. High-Performance Graphene-Based Cementitious Composites. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2019; 6:1801195. [PMID: 31065510 PMCID: PMC6498302 DOI: 10.1002/advs.201801195] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/25/2018] [Revised: 09/11/2018] [Indexed: 06/09/2023]
Abstract
This study reports on the development of a cementitious composite incorporating electrochemically exfoliated graphene (EEG). This hybrid functional material features significantly enhanced microstructure and mechanical properties, as well as unaffected workability; thus, it outperforms previously reported cementitious composites containing graphene derivatives. The manufacturing of the composite relies on a simple and efficient method that enables the uniform dispersion of EEG within cement matrix in the absence of surfactants. Different from graphene oxide, EEG is found to not agglomerate in cement alkaline environment, thereby not affecting the fluidity of cementitious composites. The addition of 0.05 wt% graphene content to ordinary Portland cement results in an increase up to 79%, 8%, and 9% for the tensile strength, compressive strength, and Young's modulus, respectively. Remarkably, it is found that the addition of EEG promotes the hydration reaction of both alite and belite, thus leading to the formation of a large fraction of 3CaO·2SiO2·3H2O (C-S-H) phase. These findings represent a major step forward toward the practical application of nanomaterials in civil engineering.
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Affiliation(s)
- Małgorzata Krystek
- Department of Structural EngineeringFaculty of Civil EngineeringSilesian University of TechnologyAkademicka 544‐100GliwicePoland
- Université de StrasbourgCNRS, ISIS8 alleé Gaspard Monge67000StrasbourgFrance
| | - Dawid Pakulski
- Université de StrasbourgCNRS, ISIS8 alleé Gaspard Monge67000StrasbourgFrance
- Faculty of ChemistryAdam Mickiewicz UniversityUmultowska 89b61‐614PoznańPoland
- Centre for Advanced TechnologiesAdam Mickiewicz UniversityUmultowska 89c61‐614PoznańPoland
| | - Violetta Patroniak
- Faculty of ChemistryAdam Mickiewicz UniversityUmultowska 89b61‐614PoznańPoland
| | - Marcin Górski
- Department of Structural EngineeringFaculty of Civil EngineeringSilesian University of TechnologyAkademicka 544‐100GliwicePoland
| | - Leszek Szojda
- Department of Structural EngineeringFaculty of Civil EngineeringSilesian University of TechnologyAkademicka 544‐100GliwicePoland
| | - Artur Ciesielski
- Université de StrasbourgCNRS, ISIS8 alleé Gaspard Monge67000StrasbourgFrance
- Centre for Advanced TechnologiesAdam Mickiewicz UniversityUmultowska 89c61‐614PoznańPoland
| | - Paolo Samorì
- Université de StrasbourgCNRS, ISIS8 alleé Gaspard Monge67000StrasbourgFrance
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16
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Prabhu A, Gimel JC, Ayuela A, Arrese-Igor S, Gaitero JJ, Dolado JS. A multi-scale approach for percolation transition and its application to cement setting. Sci Rep 2018; 8:15830. [PMID: 30361491 PMCID: PMC6202394 DOI: 10.1038/s41598-018-33918-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2018] [Accepted: 09/28/2018] [Indexed: 11/10/2022] Open
Abstract
Shortly after mixing cement grains with water, a cementitious fluid paste is formed that immediately transforms into a solid form by a phenomenon known as setting. Setting actually corresponds to the percolation of emergent network structures consisting of dissolving cement grains glued together by nanoscale hydration products, mainly calcium-silicate-hydrates. As happens in many percolation phenomena problems, the theoretical identification of the percolation threshold (i.e. the cement setting) is still challenging, since the length scale where percolation becomes apparent (typically the length of the cement grains, microns) is many times larger than the nanoscale hydrates forming the growing spanning network. Up to now, the long-lasting gap of knowledge on the establishment of a seamless handshake between both scales has been an unsurmountable obstacle for the development of a predictive theory of setting. Herein we present a true multi-scale model which concurrently provides information at the scale of cement grains (microns) and at the scale of the nano-hydrates that emerge during cement hydration. A key feature of the model is the recognition of cement setting as an off-lattice bond percolation process between cement grains. Inasmuch as this is so, the macroscopic probability of forming bonds between cement grains can be statistically analysed in smaller local observation windows containing fewer cement grains, where the nucleation and growth of the nano-hydrates can be explicitly described using a kinetic Monte Carlo Nucleation and Growth model. The most striking result of the model is the finding that only a few links (~12%) between cement grains are needed to reach setting. This directly unveils the importance of explicitly including nano-texture on the description of setting and explains why so low amount of nano-hydrates is needed for forming a spanning network. From the simulations, it becomes evident that this low amount is least affected by processing variables like the water-to-cement ratio and the presence of large quantities of nonreactive fillers. These counter-intuitive predictions were verified by ex-professo experiments that we have carried out to check the validity of our model.
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Affiliation(s)
- Achutha Prabhu
- División de Construcción Sostenible, TECNALIA, Parque Tecnológico de Bizkaia, Astondo Bidea, Edificio 700, 48160, Derio, Spain.
| | - Jean-Christophe Gimel
- MINT, UNIV Angers, INSERM 1066, CNRS 6021, Université Bretagne Loire, IBS-CHU, 4 rue Larrey, 49933, Angers, France
| | - Andrés Ayuela
- Centro de Física de Materiales, Centro Mixto CSIC-UPV/EHU, Paseo Manuel Lardizabal 5, 20018, San Sebastián, Spain.,Donostia International Physics Center, Paseo Manuel Lardizabal 3, 20018, San Sebastián, Spain
| | - Silvia Arrese-Igor
- Centro de Física de Materiales, Centro Mixto CSIC-UPV/EHU, Paseo Manuel Lardizabal 5, 20018, San Sebastián, Spain
| | - Juan J Gaitero
- División de Construcción Sostenible, TECNALIA, Parque Tecnológico de Bizkaia, Astondo Bidea, Edificio 700, 48160, Derio, Spain.,MATCON, Associated Unit CSIC-TECNALIA, Parque Tecnológico de Bizkaia, Astondo Bidea, Edificio 700, 48160, Derio, Spain
| | - Jorge S Dolado
- Centro de Física de Materiales, Centro Mixto CSIC-UPV/EHU, Paseo Manuel Lardizabal 5, 20018, San Sebastián, Spain. .,Donostia International Physics Center, Paseo Manuel Lardizabal 3, 20018, San Sebastián, Spain. .,Faculty of Civil Engineering and Geosciences, Delft University of Technology, Stevinweg 1, 2628 CN, Delft, The Netherlands.
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17
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Zhou Y, Hou D, Geng G, Feng P, Yu J, Jiang J. Insights into the interfacial strengthening mechanisms of calcium-silicate-hydrate/polymer nanocomposites. Phys Chem Chem Phys 2018. [PMID: 29528060 DOI: 10.1039/c8cp00328a] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The mechanical properties of organic/inorganic composites can be highly dependent on the interfacial interactions. In this work, with organic polymers intercalated into the interlayer of inorganic calcium silicate hydrate (C-S-H), the primary binding phase of Portland cement, great ductility improvement is obtained for the nanocomposites. Employing reactive molecular dynamics, the simulation results indicate that strong interfacial interactions between the polymers and the substrate contribute greatly to strengthening the materials, when C-S-H/poly ethylene glycol (PEG), C-S-H/poly acrylic acid (PAA), and C-S-H/poly vinyl alcohol (PVA) were subject to uniaxial tension along different lattice directions. In the x and z direction tensile processes, the Si-OCa bonds of the C-S-H gel, which were elongated and broken to form Si-OH and Ca-OH, play a critical role in loading resistance, while the incorporation of polymers bridged the neighboring silicate sheets, and activated more the hydrolytic reactions at the interfaces to avoid strain localization, thus increasing the tensile strength and postponing the fracture. On the other hand, Si-O-Si bonds of C-S-H mainly take the load when tension was applied along the y direction. During the post-yield stage, rearrangements of silicate tetrahedra occurred to prevent rapid damage. The polymer intercalation further elongates this post-yield period by forming interfacial Si-O-C bonds, which promote rearrangements and improve the connectivity of the defective silicate morphology, significantly improving the ductility. Among the polymers, PEG exhibits the strongest interaction with C-S-H, and thus C-S-H/PEG possesses the highest ductility. We expect that the molecular-scale mechanisms interpreted here will shed new light on the stress-activated chemical interactions at the organic/inorganic interfaces, and help eliminate the brittleness of cement-based materials on a genetic level.
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Affiliation(s)
- Yang Zhou
- Jiangsu Key Laboratory of Construction Materials, School of Materials Science and Engineering, Southeast University, Nanjing 211189, China and Department of Civil and Environmental Engineering, University of California, Berkeley, California 94720, USA and State Key Laboratory of High Performance Civil Engineering Materials, Jiangsu Research Institute of Building Science Co., Nanjing 211103, China
| | - Dongshuai Hou
- Department of Civil Engineering, Qingdao University of Technology, Qingdao 266033, China.
| | - Guoqing Geng
- Department of Civil and Environmental Engineering, University of California, Berkeley, California 94720, USA and Laboratory for Waste Management, Paul Scherrer Institut, 5232 Villigen PSI, Switzerland
| | - Pan Feng
- Jiangsu Key Laboratory of Construction Materials, School of Materials Science and Engineering, Southeast University, Nanjing 211189, China
| | - Jiao Yu
- Department of Civil Engineering, Qingdao University of Technology, Qingdao 266033, China.
| | - Jinyang Jiang
- Jiangsu Key Laboratory of Construction Materials, School of Materials Science and Engineering, Southeast University, Nanjing 211189, China
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18
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Jahangiri S, Mosey NJ. Density-functional tight-binding investigation of the structure, stability and material properties of nickel hydroxide nanotubes. NANOTECHNOLOGY 2018; 29:025708. [PMID: 29099392 DOI: 10.1088/1361-6528/aa981a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Nickel hydroxide is a material composed of two-dimensional layers that can be rolled up to form cylindrical nanotubes belonging to a class of inorganic metal hydroxide nanotubes that are candidates for applications in catalysis, energy storage, and microelectronics. The stabilities and other properties of this class of inorganic nanotubes have not yet been investigated in detail. The present study uses self-consistent-charge density-functional tight-binding calculations to examine the stabilities, mechanical properties, and electronic properties of nickel hydroxide nanotubes along with the energetics associated with the adsorption of water by these systems. The tight-binding model was parametrized for this system based on the results of first-principles calculations. The stabilities of the nanotubes were examined by calculating strain energies and performing molecular dynamics simulations. The results indicate that single-walled nickel hydroxide nanotubes are stable at room temperature, which is consistent with experimental investigations. The nanotubes possess size-dependent mechanical properties that are similar in magnitude to those of other inorganic nanotubes. The electronic properties of the nanotubes were also found to be size-dependent and small nickel oxyhydroxide nanotubes are predicted to be semiconductors. Despite this size-dependence, both the mechanical and electronic properties were found to be almost independent of the helical structure of the nanotubes. The calculations also show that water molecules have higher adsorption energies when binding to the interior of the nickel hydroxide nanotubes when compared to adsorption in nanotubes formed from other two-dimensional materials such as graphene. The increased adsorption energy is due to the hydrophilic nature of nickel hydroxide. Due to the broad applications of nickel hydroxide, the nanotubes investigated here are also expected to be used in catalysis, electronics, and clean energy production.
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Affiliation(s)
- Soran Jahangiri
- Department of Chemistry, Queen's University, 90 Bader Lane, Kingston, ON K7M 0A9, Canada
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19
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Douglas-Gallardo OA, Soldano GJ, Mariscal MM, Sánchez CG. Effects of oxidation on the plasmonic properties of aluminum nanoclusters. NANOSCALE 2017; 9:17471-17480. [PMID: 29106431 DOI: 10.1039/c7nr04904h] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
The scouting of alternative plasmonic materials able to enhance and extend the optical properties of noble metal nanostructures is on the rise. Aluminum is endowed with a set of interesting properties which turn it into an attractive plasmonic material. Here we present the optical and electronic features of different aluminum nanostructures stemming from a multilevel computational study. Molecular Dynamics (MD) simulations using a reactive force field (ReaxFF), carefully validated with Density Functional Theory (DFT), were employed to mimic the oxidation of icosahedral aluminum nanoclusters. Resulting structures with different oxidation degrees were then studied through the Time-Dependent Density Functional Tight Binding (TD-DFTB) method. A similar approach was used in aluminum nanoclusters with a disordered structure to study how the loss of crystallinity affects the optical properties. To the best of our knowledge, this is the first report that addresses this issue from the fully atomistic time-dependent approach by means of two different and powerful simulation tools able to describe quantum and physicochemical properties associated with nanostructured particles.
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Affiliation(s)
- Oscar A Douglas-Gallardo
- INFIQC (UNC-CONICET), Departamento de Qumica Teŕica y Computacional, Facultad de Ciencias Qumicas, Universidad Nacional de Cŕdoba, Medina Allende y Haya de la Torre, Ciudad Universitaria, Cŕdoba, X5000HUA Cŕdoba, Argentina.
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20
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Dupuis R, Dolado JS, Benoit M, Surga J, Ayuela A. Quantum Nuclear Dynamics of Protons within Layered Hydroxides at High Pressure. Sci Rep 2017; 7:4842. [PMID: 28687787 PMCID: PMC5501843 DOI: 10.1038/s41598-017-04080-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2017] [Accepted: 05/08/2017] [Indexed: 11/09/2022] Open
Abstract
Studies of the structure of hydroxides under pressure using neutron diffraction reveal that the high concentration of hydrogen is distributed in a disordered network. The disorder in the hydrogen-bond network and possible phase transitions are reported to occur at pressures within the range accessible to experiments for layered calcium hydroxides, which are considered to be exemplary prototype materials. In this study, the static and dynamical properties of these layered hydroxides are investigated using a quantum approach describing nuclear motion, shown herein to be required particularly when studying diffusion processes involving light hydrogen atoms. The effect of high-pressure on the disordered hydrogen-bond network shows that the protons tunnel back and forth across the barriers between three potential minima around the oxygen atoms. At higher pressures the structure has quasi two-dimensional layers of hydrogen atoms, such that at low temperatures this causes the barrier crossing of the hydrogen to be significantly rarefied. Furthermore, for moderate values of both temperature and pressure this process occurs less often than the usual mechanism of proton transport via vacancies, limiting global proton diffusion within layers at high pressure.
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Affiliation(s)
- Romain Dupuis
- DIPC, Paseo Manuel de Lardizabal, 4, 20018, San Sebastian, Spain.
| | - Jorge S Dolado
- TECNALIA, Parque Científico y Tecnológico de Bizkaia 700 Edificio, 48160, Elexalde Derio, Spain
| | - Magali Benoit
- CEMES, 29 Rue Jeanne Marvig, 31055, Toulouse Cedex 4, France
| | - Jose Surga
- INTEVEP, Urb. Santa Rosa, Los Teques, 1201, Venezuela
| | - Andrés Ayuela
- DIPC, Paseo Manuel de Lardizabal, 4, 20018, San Sebastian, Spain.,CFM-MPC CSIC-UPV/EHU, Paseo Manuel de Lardizabal, 5, 20018, San Sebastian, Spain
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21
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Diez-Garcia M, Gaitero JJ, Dolado JS, Aymonier C. Ultra-Fast Supercritical Hydrothermal Synthesis of Tobermorite under Thermodynamically Metastable Conditions. Angew Chem Int Ed Engl 2017; 56:3162-3167. [PMID: 28156037 DOI: 10.1002/anie.201611858] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2016] [Indexed: 11/09/2022]
Abstract
Tobermorite is a fibrillar mineral of the family of calcium silicates. In spite of not being abundant in nature, its structure and properties are reasonably well known because of its interest in the construction industry. Currently, tobermorite is synthesized by hydrothermal methods at mild temperatures. The problem is that such processes are very slow (>5 h) and temperature cannot be increased to speed them up because tobermorite is metastable over 130 °C. Furthermore the product obtained is generally foil-like and not very crystalline. Herein we propose an alternative synthesis method based on the use of a continuous flow reactor and supercritical water. In spite of the high temperature, the transformation of tobermorite to more stable phases can be prevented by accurately controlling the reaction time. As a result, highly crystalline fibrillar tobermorite can be obtained in just a few seconds under thermodynamically metastable conditions.
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Affiliation(s)
- Marta Diez-Garcia
- CNRS, Univ. Bordeaux, ICMCB, UPR 9048, F-33600, Pessac, France.,Sustainable Construction Division, Tecnalia Parque tecnológico de Bizkaia, C/Geldo, Edif. 700, 48160, Derio, Spain.,UPV-EHU, Dep. Mining-Metallurgy Engeneering and Mat. Science, Alameda Urquijo s/n, 48013, Bilbao, Spain
| | - Juan J Gaitero
- Sustainable Construction Division, Tecnalia Parque tecnológico de Bizkaia, C/Geldo, Edif. 700, 48160, Derio, Spain
| | - Jorge S Dolado
- Sustainable Construction Division, Tecnalia Parque tecnológico de Bizkaia, C/Geldo, Edif. 700, 48160, Derio, Spain
| | - Cyril Aymonier
- CNRS, Univ. Bordeaux, ICMCB, UPR 9048, F-33600, Pessac, France
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22
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Diez-Garcia M, Gaitero JJ, Dolado JS, Aymonier C. Ultra-Fast Supercritical Hydrothermal Synthesis of Tobermorite under Thermodynamically Metastable Conditions. Angew Chem Int Ed Engl 2017. [DOI: 10.1002/ange.201611858] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Marta Diez-Garcia
- CNRS, Univ. Bordeaux, ICMCB, UPR 9048; F-33600 Pessac France
- Sustainable Construction Division; Tecnalia Parque tecnológico de Bizkaia; C/Geldo, Edif. 700 48160 Derio Spain
- UPV-EHU; Dep. Mining-Metallurgy Engeneering and Mat. Science; Alameda Urquijo s/n 48013 Bilbao Spain
| | - Juan J. Gaitero
- Sustainable Construction Division; Tecnalia Parque tecnológico de Bizkaia; C/Geldo, Edif. 700 48160 Derio Spain
| | - Jorge S. Dolado
- Sustainable Construction Division; Tecnalia Parque tecnológico de Bizkaia; C/Geldo, Edif. 700 48160 Derio Spain
| | - Cyril Aymonier
- CNRS, Univ. Bordeaux, ICMCB, UPR 9048; F-33600 Pessac France
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Jahangiri S, Mosey NJ. Effects of reduced dimensionality on the properties of magnesium hydroxide and calcium hydroxide nanostructures. Phys Chem Chem Phys 2017; 19:1963-1974. [DOI: 10.1039/c6cp07968g] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
DFT and SCC-DFTB calculations shed light on the size and dimensionality dependence of the properties of metal hydroxides.
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24
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Hajilar S, Shafei B. Assessment of structural, thermal, and mechanical properties of portlandite through molecular dynamics simulations. J SOLID STATE CHEM 2016. [DOI: 10.1016/j.jssc.2016.09.026] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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25
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Yu Z, Zhou A, Lau D. Mesoscopic packing of disk-like building blocks in calcium silicate hydrate. Sci Rep 2016; 6:36967. [PMID: 27845376 PMCID: PMC5109495 DOI: 10.1038/srep36967] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2016] [Accepted: 10/24/2016] [Indexed: 12/02/2022] Open
Abstract
At 100-nanometer length scale, the mesoscopic structure of calcium silicate hydrate (C-S-H) plays a critical role in determining the macroscopic material properties, such as porosity. In order to explore the mesoscopic structure of C-S-H, we employ two effective techniques, nanoindentation test and molecular dynamics simulation. Grid nanoindentation tests find different porosity of C-S-H in cement paste specimens prepared at varied water-to-cement (w/c) ratios. The w/c-ratio-induced porosity difference can be ascribed to the aspect ratio (diameter-to-thickness ratio) of disk-like C-S-H building blocks. The molecular dynamics simulation, with a mesoscopic C-S-H model, reveals 3 typical packing patterns and relates the packing density to the aspect ratio. Illustrated with disk-like C-S-H building blocks, this study provides a description of C-S-H structures in complement to spherical-particle C-S-H models at the sub-micron scale.
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Affiliation(s)
- Zechuan Yu
- Department of Architecture and Civil Engineering, City University of Hong Kong, Hong Kong, China
| | - Ao Zhou
- Department of Architecture and Civil Engineering, City University of Hong Kong, Hong Kong, China
| | - Denvid Lau
- Department of Architecture and Civil Engineering, City University of Hong Kong, Hong Kong, China.,Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
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26
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Cardoso SSS, Cartwright JHE, Steinbock O, Stone DA, Thomas NL. Cement nanotubes: on chemical gardens and cement. Struct Chem 2016. [DOI: 10.1007/s11224-016-0811-0] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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27
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Paupitz R, Junkermeier CE, van Duin ACT, Branicio PS. Fullerenes generated from porous structures. Phys Chem Chem Phys 2014; 16:25515-22. [DOI: 10.1039/c4cp03529a] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Structural and electronic properties of macromolecules, which have the architecture of fullerenes, were studied using reactive and density functional-based methods.
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Affiliation(s)
- Ricardo Paupitz
- Departamento de Física
- IGCE
- Univ Estadual Paulista
- UNESP
- Rio Claro, Brazil
| | - Chad E. Junkermeier
- Department of Mechanical and Nuclear Engineering
- The Pennsylvania State University
- University Park, USA
| | - Adri C. T. van Duin
- Department of Mechanical and Nuclear Engineering
- The Pennsylvania State University
- University Park, USA
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