Search Results (8)

Novel ferrite/polyurethane nanocomposites were synthesized using the in situ polymerization method after the addition of different spinel nanoferrite particles (copper, zinc, and copper–zinc) and examined as potential coatings for medical devices and implants in vascular tissue engineering. The influence of the nanoferrite type on the structure and functional characteristics of the polyurethane composites was investigated by FTIR, SWAXS, AFM, TGA, DSC, nanoindentation, swelling behavior, water contact angle, and water absorption measurements. Biocompatibility was evaluated by examining the cytotoxicity and adhesion of human endothelial cells and fibroblasts onto prepared composites and performing a protein adsorption test. The antioxidant activity was detected by UV–VIS spectroscopy using a 1,1-diphenyl-2-picrylhydrazyl (DPPH) scavenging assay. Embedding the different types of nanoparticles in the polyurethane matrix increased phase mixing, swelling ability, and DPPH scavenging, decreased surface roughness, and differently affected the stiffness of the prepared materials. The composite with zinc ferrite showed improved mechanical properties, hydrophilicity, cell adhesion, and antioxidant activity with similar thermal stability, but lower surface roughness and crosslinking density compared to the pristine polyurethane matrix. The in vitro biocompatibility evaluation demonstrates that all nanocomposites are non-toxic, exhibit good hemocompatibility, and promote cell adhesion, and recommends their use as biocompatible materials for the development of coatings for vascular implants. Full article

The presence of high concentrations of flammable gases and volatile organic compounds in the atmosphere has been widely reported to be detrimental to human survival. A lot of research effort has been put toward finding an efficient means of quick detection of these gases below their ‘immediately dangerous to life or health’ concentrations. Detecting these gases in an oxygen-deficient environment is a crucial task to consider and has been overlooked. In this research, double-substitution spinel with the chemical formula Co_1−2xNi_xMn_xFe_2−yCe_yO₄, where 0 ≤ x = y ≤ 0.3, was prepared via the glycol-thermal technique. The final products, following appropriate substitution, were CoFe₂O₄ (dried naturally), CoFe₂O₄ (dried with infrared lamp), Co_0.8Ni_0.1Mn_0.1Fe_1.9Ce_0.1O₄, Co_0.6Ni_0.2Mn_0.2Fe_1.8Ce_0.2O₄ and Co_0.4Ni_0.3Mn_0.3Fe_1.7Ce_0.3O₄ spinel ferrites. The X-ray diffractometry (XRD), high-resolution transmission electron micrographs (HRTEM) and X-ray photoelectron spectroscopy (XPS) of the samples confirmed the formation of the spinel. The gas sensing performance of these samples was tested at the operating temperature of 225 °C toward liquefied petroleum gas (LPG), ammonia, ethanol and propanol. The Co_0.8Ni_0.1Mn_0.1Fe_1.9Ce_0.1O₄-based sensor was selective to LPG, with a high response of 116.43 toward 6000 ppm of LPG when helium was used as the carrier gas, 3.35 when dry air was the carrier gas, 4.4 when nitrogen was the carrier gas, but it was not sensitive when argon was used as the carrier gas. Full article

Nanosized spinel ferrites MFe₂O₄ (M = Mn, Co, Ni, Cu, Zn)-coated flaky FeSiAl alloy composites were synthesized successfully. Nano-ferrites preferentially grow into nanoplatelets due to induced or restricted growth on the flaky surface of FeSiAl. With annealing temperature increasing, the ferrites’ nanosheets thicken gradually and then grow into irregular particles. The annealing temperature not only affects the nanosized morphology and coating but also the magnetic properties of flaky FeSiAl composites. The saturation magnetization of CuFe₂O₄- or NiFe₂O₄-coated FeSiAl is approximate 69 emu/g, where the value of MnFe₂O₄-, CoFe₂O₄- and ZnFe₂O₄-coated FeSiAl show a decreasing trend generally from 64 emu/g to 55.7 emu/g annealing at 800 °C, respectively. The saturation magnetization of flaky FeSiAl composites was improved with the increased annealing temperature, except for those coated with ZnFe₂O₄ and NiFe₂O₄. These results are useful for improving the comprehensive properties of ferrite-coated flaky FeSiAl alloy composites. Full article

Biogenic routes for the synthesis of nanoparticles are environmentally friendly, nontoxic, biocompatible, and cost-effective compared to traditional synthesis methods. In this study, cobalt ferrite was synthesized using Zingiber officinale and Elettaria cardamom Seed extracts. Effect of copper contents (x = 0.0, 0.3, 0.6 and 0.9) on the plant extracted ${\mathrm{Cu}}_{\mathrm{x}}({\mathrm{Co}}_{1-\mathrm{x}}{\mathrm{Fe}}_2{\mathrm{O}}_4)$ was investigated by XRD, SEM, EDX, UV-Vis., PL, FE-SEM, FTIR and photocatalytic activity. XRD results revealed that nanoparticles exhibit a cubical spinel structure with an average diameter of 7–45 nm, calculated by the Debye Scherer formula. The value of the lattice parameter decreased from 8.36 Å to 8.08 Å with substitution of copper, which can be attributed to mismatch of ionic radii of Cu²⁺ (0.73 Å) and Co²⁺ (0.74 Å) ions. SEM analysis showed that nanoparticles exhibit a spherical shape (~13 nm diameter) for undoped samples and low Cu concentration, while they changed to a hexagonal structure at higher Cu concentration (x = 0.9) with a diameter ~46 nm and a decreased degree of agglomeration. FE-SEM further confirmed the nanoparticles’ size and shape. EDX analysis confirmed the presence of cobalt, iron, and oxygen without contamination. The optical absorption spectra of UV-vis and PL showed red-shift, which can be accredited to larger crystalline sizes of nanoparticles. FTIR spectra showed two main bands at 410 and 605 cm⁻¹, indicating the presence of intrinsic vibrations of the octahedral and tetrahedral complexes, respectively. The photocatalytic activity of Co_0.4Cu_0.6 Fe₂O₄ nanoparticles was investigated using methylene blue (MB) and methyl orange (MO) dyes under visible light irradiation. The degradation rate (93.39% and 83.15%), regression correlation coefficient (0.9868 and 0.9737) and rate constant (0.04286 and 0.03203 rate·min⁻¹) were calculated for MB and MO, respectively. Mechanisms for the formation and photocatalytic activity of Cu-substituted plant-extracted cobalt ferrite were discussed. The Co_0.4Cu_0.6 Fe₂O₄ nanoferrite was found to be an efficient photocatalyst, and can be exploited for wastewater treatment applications for MB/MO elimination. Full article

Using the auto combustion flash method, ${\mathrm{Ni}}_{1-\mathrm{x}}^{+2}{\mathrm{Mg}}_{\mathrm{x}}^{+2}{\mathrm{Fe}}_2^{+3}{\mathrm{O}}_4$ (x = 0, 0.2, 0.6, 0.8 and 1) nano-ferrites were synthesized. All samples were thermally treated at 973 K for 3 h. The structural analysis for the synthesized samples was performed using XRD, high-resolution transmission electron microscopy (HRTEM), and FTIR. Scanning electron microscopy (SEM) was undertaken to explore the surface morphology of all the samples. The thermal stability of these samples was investigated using thermogravimetric analysis (TGA). XRD data show the presence of a single spinel phase for all the prepared samples. The intensity of the principal peak of the spinel phase decreases as Mg content increases, showing that Mg delays crystallinity. The Mg content raised the average grain size (D) from 0.084 μm to 0.1365 μm. TGA shows two stages of weight loss variation. The vibrating sample magnetometer (VSM) measurement shows that magnetic parameters, such as initial permeability (μ_i) and saturation magnetization (M_s), decay with rising Mg content. The permeability and magnetic anisotropy at different frequencies and temperatures were studied to show the samples’ magnetic behavior and determine the Curie temperature (T_C), which depends on the internal structure. The electrical resistivity behavior shows the semi-conductivity trend of the samples. Finally, the dielectric constant increases sharply at high temperatures, explained by the increased mobility of charge carriers, and decreases with increasing frequency. Full article

A series of cobalt-inserted copper zinc ferrites, Cu_0.6Co_xZn_0.4−xFe₂O₄ (x = 0.0, 0.1, 0.2, 0.3, 0.4) having cubic spinel structure were prepared by the coprecipitation method. Various characterization techniques, including XRD, FTIR, UV-vis and I–V were used to investigate structural optical and electrical properties, respectively. The lattice constant was observed to be decreased as smaller ionic radii Co²⁺ (0.74 Å) replaced the higher ionic radii Zn²⁺ (0.82 Å). The presence of tetrahedral and octahedral bands was confirmed by FTIR spectra. Optical bandgap energy was determined in the range of 4.44–2.05 eV for x = 0.0 to 0.4 nanoferrites, respectively. DC electrical resistivity was measured and showed an increasing trend (5.42 × 10⁸ to 6.48 × 10⁸ Ω·cm) with the addition of cobalt contents as cobalt is more conductive than zinc. The range of DC electrical resistivity (10⁸ ohm-cm) makes these nanomaterials potential candidates for telecommunication devices. Full article

Nickel zinc nanoferrites (Ni_1−xZn_xFe₂O₄) were synthesized via a chemical co-precipitation method having stoichiometric proportion (x) altering from 0.00 to 1.00 in steps of 0.25. The synthesized nanoparticles were sintered at 800 °C for 12 h. X-ray diffraction patterns illustrate that the nanocrystalline cubic spinel ferrites have been obtained after sintering. The Scherrer formula is used to evaluate the particle size using the extreme intense peak (311). The experimental results demonstrate that the precipitated particles’ size was in the range of 20–70 nm. Scanning electron microscopy (SEM) is used to investigate the elemental configuration and morphological characterizations of all the prepared samples. FTIR spectroscopy data for respective sites were examined in the range of 300–1000 cm⁻¹. The higher frequency band ν₁ was assigned due to tetrahedral complexes, while the lower frequency band ν₂ was allocated due to octahedral complexes. Our experimental results demonstrate that the lattice constant a₀ increases while lattice strain decreases with increasing zinc substitution in nickel zinc nanoferrites. Full article

Three kinds of magnesium-based spinel nanoferrites with the chemical formulas of MgFe₂O₄ (Mg ferrite), Mg_0.9Mn_0.1Fe₂O₄ (Mg-Mn ferrite), and Mg_0.9Mn_0.1In_0.1Fe_1.9O₄ (Mg-Mn-In ferrite) were synthesized by hydrothermal route. We report the composition-dependent magnetic parameters and microwave properties of Mg-based ferrite nanoparticles. XRD results revealed that the Mg-based ferrite nanoparticles exhibited a cubic spinel structure and had an average nanocrystallite size in the range of 5.8–2.6 nm. Raman spectroscopy analysis confirmed the formation of cubic-spinel phase Mg-based nanoferrites. The room-temperature magnetization measurements indicated that the Mg ferrite nanoparticles had superparamagnetic behavior; whereas the Mg-Mn and Mg-Mn-In ferrite nanoparticles exhibited a paramagnetic nature. The microwave properties of obtained ferrite nanoparticles were studied by alternating current (AC) magnetic susceptibility measurement and electron paramagnetic resonance (EPR) spectroscopy. It was found that the un-substituted Mg ferrite sample exhibited microwave characteristics better than those of the Mn substituted and Mn-In co-substituted Mg ferrite samples. Full article