Structural, magnetic, optical properties and cation distribution of nanosized Ni0.3Cu0.3Zn0.4TmxFe2-xO4 (0.0 ≤ x ≤ 0.10) spinel ferrites synthesized by ultrasound irradiation

Impact of Ga3+ Ions on the Structure, Magnetic, and Optical Features of Co-Ni Nanostructured Spinel Ferrite Microspheres

Co-Ni ferrite is one of the crucial materials for the electronic industry. A partial substitution with a rare-earth metal brings about modification in crystal lattice and broadens knowledge in the discovery of new magnetic material. Current work reports a Ga³⁺ substitution in the Co-Ni ferrite with composition Co_0.5Ni_0.5Fe_2-xGa_xO₄ (where x = 0.0, 0.2, 0.4, 0.6, 0.8, and 1.0), herein referred to as spinel ferrite microspheres (CoNiGa-SFMCs). The samples were crystallized hydrothermally showing a hollow sphere morphology. The crystal phase, magnetic, morphology, and optical behaviour were examined using various microscopy and spectroscopic tools. While the XRD confirmed the phase of SFMCs, the crystallite size varied between 9 and 12 nm. The Tauc plot obtained from DRS (diffuse reflectance spectroscopy) shows the direct optical energy bandgap (E_g) of the products, with the pristine reading having the value of 1.41 eV E_g; the band gap increased almost linearly up to 1.62 eV along with rising the Ga³⁺ amount. The magnetic features, on the other hand, indicated the decrease in coercivity (H_c) as more Ga³⁺ is introduced. Moreover, there was a gradual increase in both saturation magnetization (M_s) and magnetic moment (nB) with increasing amount of Ga³⁺ till x = 0.6 and then a progressive decline with increases in the x content; this was ascribed to the spin-glass-like behavior at low temperatures. It was detected that magnetic properties correlate well with crystallite/particle size, cation distribution, and anisotropy.

Influence of size polydispersity on magnetic field tunable structures in magnetic nanofluids containing superparamagnetic nanoparticles

We probe the influence of particle size polydispersity on field-induced structures and structural transitions in magnetic fluids (ferrofluids) using phase contrast optical microscopy, light scattering and Brownian dynamics simulations. Three different ferrofluids containing superparamagnetic nanoparticles of different polydispersity indices (PDIs) are used. In a ferrofluid with a high PDI (∼0.79), thin chains, thick chains, and sheets are formed on increasing the in-plane magnetic field, whereas isotropic bubbles, and hexagonal and lamellar/stripe structures are formed on increasing the out-of-plane magnetic field over the same range. In contrast, no field-induced aggregates are seen in the sample with low polydispersity under the above conditions. In a polydisperse sample, bubbles are formed at a very low magnetic field strength of 30 G. Insights into the structural evolution with increasing magnetic field strength are obtained by carrying out Brownian dynamics simulations. The crossovers from isotropic, through hexagonal columnar, to lamellar/stripe structures observed with increasing field strength in the high-polydispersity sample indicate the prominent roles of large, more strongly interacting particles in structural transitions in ferrofluids. Based on the observed microstructures, a phase diagram is constructed. Our work opens up new opportunities to develop optical devices and access diverse structures by tuning size polydispersity.

Sonochemical catalysis as a unique strategy for the fabrication of nano-/micro-structured inorganics

Ultrasound-assisted approaches, as an important trend in material synthesis, have emerged for designing and creating nano-/micro-structures. This review simply presents the basic principles of ultrasound irradiation including acoustic cavitation, sonochemical effects, physical and/or mechanical effects, and on the basis of the latest progress, it newly summarizes sonochemical catalysis for the fabrication of nano-structured or micro-structured inorganic materials such as metals, alloys, metal compounds, non-metal materials, and inorganic composites, where the theories or mechanisms of catalytic synthetic routes, and the morphologies, structures, sizes, properties and applications of products are described in detail. In the review, a few technological potentials and probable challenges of sonochemical catalysis are also highlighted for the future advance of synthesis methods. Therefore, sonochemical catalysis or ultrasound-assisted synthesis will serve as a unique strategy to reveal its great significance in material fabrication.

Synthesis and biological characterization of Mn0.5Zn0.5EuxDyxFe1.8-2xO4 nanoparticles by sonochemical approach

Metallic nanoparticles (NPs) possess unique properties which makes them attractive candidates for various applications especially in field of experimental medicine and drug delivery. Many approaches were developed to synthesize divers and customized metallic NPs that can be useful in many areas such as, experimental medicine, drug design, drug delivery, electrical and electronic engineering, electrochemical sensors, and biochemical sensors. Among different metallic nanoparticles, manganese (Mn) NPs are the most prominent materials, in the present study, we have synthetized unique Mn_0.5Zn_0.5Dy_xEu_xFe_1.8-2xO₄ NPs by using ultrasonication method (x ≤ 0.1). The structure, and surface morphology of Mn_0.5Zn_0.5Dy_xEu_xFe_1.8-2xO₄ NPs was characterized by XRD, SEM, TEM and EDX methods. We have examined the biological effects of Mn_0.5Zn_0.5Dy_xEu_xFe_1.8-2xO₄ NPs on both normal (HEK-293) and cancerous (HCT-116) cells. We have found that the treatment of Mn_0.5Zn_0.5Dy_xEu_xFe_1.8-2xO₄ NPs post 48 h, showed significant decline in cancer cells population as revealed by MTT assay. The IC₅₀ value of Mn_0.5Zn_0.5Dy_xEu_xFe_1.8-2xO₄ NPs was ranged between (2.35 μg/mL to 2.33 μg/mL). To check the specificity of the actions, we found that the treatment of Mn_0.5Zn_0.5Dy_xEu_xFe_1.8-2xO₄ NPs did not produce any effects on the normal cells, which suggest that Mn_0.5Zn_0.5Dy_xEu_xFe_1.8-2xO₄ NPs selectively targeted the cancerous cells. The anti-bacterial properties of Mn_0.5Zn_0.5Dy_xEu_xFe_1.8-2xO₄ NPs were also evaluated by MIC and MBC assays. We suggest that Mn_0.5Zn_0.5Dy_xEu_xFe_1.8-2xO₄ NPs produced by sonochemical method possess potential anti-cancer and anti-bacterial capabilities.

Synthesis of Mn0.5Zn0.5SmxEuxFe1.8-2xO4 Nanoparticles via the Hydrothermal Approach Induced Anti-Cancer and Anti-Bacterial Activities

Manganese metallic nanoparticles are attractive materials for various biological and medical applications. In the present study, we synthesized unique Mn_0.5Zn_0.5Sm_xEu_xFe_1.8−2xO₄ (0.01 ≤ x ≤ 0.05) nanoparticles (NPs) by using the hydrothermal approach. The structure and surface morphology of the products were determined by X-ray powder diffraction (XRD), transmission electron and scanning electron microcopies (TEM and SEM), along with energy dispersive X-ray spectroscopy (EDX). We evaluated the impact of Mn_0.5Zn_0.5Sm_xEu_xFe_1.8−2xO₄ NPs on both human embryonic stem cells (HEK-293) (normal cells) and human colon carcinoma cells (HCT-116) (cancerous cells). We found that post-48 h of treatment of all products showed a significant decline in the cancer cell population as revealed by microscopically and the (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) tetrazolium (MTT) assay. The inhibitory concentration (IC₅₀) values of the products ranged between 0.75 and 2.25 µg/mL. When tested on normal and healthy cells (HEK-293), we found that the treatment of products did not produce any effects on the normal cells, which suggests that all products selectively targeted the cancerous cells. The anti-bacterial properties of the samples were also evaluated by Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) assays, which showed that products also inhibited the bacterial growth.

Sonochemical synthesis and physical properties of Co0.3Ni0.5Mn0.2EuxFe2-xO4 nano-spinel ferrites

Nanoparticles (NPs) of composition Co_0.3Ni_0.5Mn_0.2Eu_xFe_2-xO₄, where 0.00 ≤ x ≤ 0.10 (hereafter called CNMEuF) were synthesized by sonochemical approach using UZ SONOPULS HD 2070 ultrasonic homogenizer (frequency of 20 kHz and power of 70 W). As-synthesized samples were characterized thoroughly to determine the effects of europium ions (Eu³⁺) substitution on their structure, morphology and magnetic traits. Structural analyses of the synthesized NPs confirmed their high purity and crystalline cubic phases. Percent diffuse reflectance (%DR) data and Kubelka-Munk theory were exploited to evaluate the optical band gap energies of the studied CNMEuF NPs. Values of optical band gap energies obtained from the Tauc plots were observed in the range of 1.47-1.58 eV. The hysteresis loops (at room temperature and 10 K) of synthesized NPs were analyzed to determine their magnetic properties. These NPs disclosed superparamagnetic and hard ferrimagnetic character at room temperature and 10 K, respectively. With exception, the sample with x = 0.10 revealed soft ferrimagnetic behavior at 10 K. Eu³⁺ doping was shown to have significant influence on the structure and magnetic attributes of the proposed CNMEuF NPs. Values of various magnetic parameters of proposed compositions were reduced with the increase in Eu³⁺ dopant contents.

Structural, magnetic, optical properties and cation distribution of nanosized Co0.7Zn0.3TmxFe2-xO4 (0.0 ≤ x ≤ 0.04) spinel ferrites synthesized by ultrasonic irradiation

This study expressed the influence of Tm substitution on the structural, optical and magnetic properties of Co-Zn spinel ferrites (Co_0.7Zn_0.3Tm_xFe_2-xO₄ (0.0 ≤ x ≤ 0.04)). The different compositions were synthesized by sonochemical method using Qsonica ultrasonic homogenizer, frequency: 20 kHz and power: 70 W for 60 min. XRD patterns proved the presence of single-phase spinel ferrites with crystallites size in the 8-10 nm range. Cation distribution approved the occupancy of octahedral (B) site by Tm. The morphology and the elements stoichiometry are obtainable through FE-SEM, EDX and elemental mapping. Optical band gap (E_g) values were estimated via DR % (percent diffuse reflectance) investigations and Kubelka-Munk theory. Tauc plots revealed that direct E_g values are ranging between 1.49 and 1.68 eV. The analyses of magnetization versus magnetic field, M(H), were performed. The following magnetic parameters like saturation magnetization M_s, squareness ratio (SQR = M_r/M_s), magnetic moment n_B, coercivity H_c and remanence M_r have been evaluated. M(H) curves revealed the superparamagnetic (SP) at RT and ferromagnetic property at 10 K. It was showed that the Tm³⁺ substitutions significantly affect the magnetic properties of host spinel ferrites. An increasing trend in the M_s, M_r, H_c, and n_B values was noticed for lower Tm³⁺ substitution content.

Impact of La3+ and Y3+ ion substitutions on structural, magnetic and microwave properties of Ni0.3Cu0.3Zn0.4Fe2O4 nanospinel ferrites synthesized via sonochemical route

In the current study, Ni_0.4Cu_0.2Zn_0.4La_xY_xFe_2−xO₄ (x = 0.00 − 0.10) nanospinel ferrites (NSFs) were fabricated via an ultrasonic irradiation route. The creation of single phase of spinel nanoferrites (NSFs) was investigated by X-ray powder diffractometry (XRD) and selected area diffraction pattern (SAED). The cubic morphology of all samples was confirmed by scanning and transmission electron microscopies (SEM and TEM) respectively. The UV-Vis investigations provided the direct optical energy band gap values in a narrow photon energy interval of 1.87–1.92 eV. The ⁵⁷Fe Mössbauer spectroscopy analysis explained that the hyperfine magnetic fields of Octahedral (Oh) and Tetrahedral (Td) sites decreased with substitution. The paramagnetic properties of NPs decrease with increase of content of doped ions. Investigations of magnetic properties reveal a superparamagnetic nature at 300 K and soft ferromagnetic trait at 10 K. The M_s (saturation magnetization) and M_r (remanence) decrease and the H_c (coercivity) increases slightly with La³⁺ and Y³⁺ substitution. The observed magnetic traits are deeply discussed in relation with the morphology, structure, magnetic moments and cation distributions. The microwave characterization of the prepared NSFs showed that, dissipation (i.e., absorption) of incoming microwave energy occurs at a single frequency, for each sample, lying between 7 and 10.5 GHz. The reflection losses (RL) at these frequencies range from −30 to −40 dB and the mechanism of which is explained in the framework of dipolar relaxation and spin rotation. The best microwave properties were obtained with a LaY concentration of x = 0.08 having an RL of −40 dB @ 10.5 GHz and an absorption bandwidth of 8.4 GHz @ −10 dB. With these high values of RL and absorbing bandwidth, LaY doped NiCuZn NSF products would be promising candidates for radar absorbing materials in the X-band.

The best microwave properties for the NSFs were obtained with an LaY concentration of x = 0.08, RL of −40 dB @ 10.5 GHz and absorption bandwidth of 8.4 GHz @ −10 dB. The NSF products show promise as radar absorbing materials in the X-band.