No abstract

This study presents a modification of structure-dependent elastic, thermodynamic, magnetic, transport and magneto-dielectric properties of a Ni–Zn–Co ferrite tailored by Gd3+ substitution at the B-site replacing Fe3+ ions.

We have investigated the Vanadium- (V) substituted Ni–Zn–Co ferrites where the samples are prepared using the solid-state reaction technique. The impact of V5+ substitution on the structural, magnetic, dielectric and electrical properties of Ni–Zn–Co ferrites has been studied. The XRD analysis confirms the formation of a single-phase cubic spinel structure. The lattice constants have been calculated both theoretically and experimentally along with other structural parameters such as bulk density, x-ray density and porosity. The FESEM images are studied for analyzing the surface morphology. FTIR measurement confirms spinel structure formation. The saturation magnetization (M s), coercive field (H c) and Bohr magnet on (μ B) are calculated from the obtained M-H loops. The temperature-dependent permeability is studied to obtain the Curie temperature. The frequency and the composition dependence of permeability are also analyzed. Frequency dependent dielectric behavior and ac resistivity are also investigated. An inverse relationship is observed between the composition dependent dielectric constant and ac resistivity. The obtained results such as the electrical resistivity, dielectric constants and magnetic properties suggest the appropriateness of the studied ferrites in microwave device applications.

No abstract

Copper oxide (CuO) thin films have been deposited on glass substrates by a facile sol-gel dipcoating technique with varying withdrawal speeds from 0.73 to 4.17 mm/s. The variation of film thickness manifested by dip-coating withdrawal speeds was investigated in detail to investigate its effect on the structural, morphological, opto-electrical, and wettability properties of CuO thin films for CO2 gas-sensing applications. The crystallinity, as well as phase purity of dip-coated CuO, were confirmed by both X-ray diffraction (XRD) and Raman spectral analyses. The surface morphology of the films characterized by the scanning electron microscopy (SEM) revealed that pore density decreases with the increase of withdrawal speeds and grain size is found to increase with the increase of film thickness corroborating the XRD results. The optical bandgap of dipcoated CuO films was estimated in the range of 1.47 -1.52 eV from the UV-VIS-NIR transmission data and it is found to decrease with the increment of Urbach tail states accompanied by the increase of film thickness. The ratio of the electrical and optical conductivity of CuO films is found to decrease with increasing withdrawal speeds due to the variation of carrier concentration. Among all the studied films, the sample deposited to a 0.73 mm/s withdrawal speed exhibited the highest crystallinity, porous morphology, highest pore density, opto-electrical conductivity as well as water contact angle, and therefore maximum gas sensing response of carbon dioxide (CO2) vapor in the air recorded at room temperature.

No abstract

No abstract

GaAs) m (Fe) n ] p composite films on GaAs(001) substrates obtained by molecular beam deposition methods at T s = 580°C have been thermally annealed, and magnetic/structural changes caused by the annealing have been measured to study the relation between room-temperature photo-magnetic effect and by-products in composite films. Annealing inhomogeneous [(GaAs) 8 (Fe) 5 ] 20 film, prepared by alternate beam deposition of Fe and GaAs, results in an increase in saturation magnetization, whereas the room-temperature photo-enhanced magnetization (RT-PEM) vanishes. Metamagnetic Fe 3 Ga 4 is suppressed with the formation of ferromagnetic Fe 3 Ga 2-x As x . Observed results suggest two important points : firstly, metamagnetic Fe 3 Ga 4 compound is most likely meta-stable bi-product and may play a principle role for RT-PEM, and secondly, ferromagnetic Fe 3 GaAs and its derivatives are the stable form in Ga-As-Fe ternary system.