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Abstract: Spinel-perovskite nanocomposites of xCrFe2O4–(1−x)BiFeO3 with x=0.0, 0.1, 0.2, 0.3, 0.4 were prepared by sol gel method. The XRD showed the phase formation of nanocomposites at 700°C. Particle size was observed to be ∼100nm by TEM. The variation of dielectric constant and dielectric loss with frequency showed dispersion in the low frequency range. Magnetization was found to increase with increasing concentration of ferrite content. Dielectric analysis showed the conducting behaviour at higher temperature. Magnetocapacitance was also observed in the prepared nanocomposites which may be the sign of magnetoelectric coupling in the synthesized nanocomposites at room temperature. [Copyright &y& Elsevier]

Abstract: We report the study of structural, optical and magnetic properties of (1−x)ZnO–xMgO (x=0.35, 0.40, 0.45 and 0.50) composites prepared by solid state reaction method. X-ray diffraction pattern confirms the presence of both the phases associated with ZnO (hexagonal) and MgO (cubic), which is revealed through the existence of (111) and (200) peaks in addition to ZnO peaks. The lattice parameter c as calculated using X-ray analysis undergoes shrinkage with increasing content of MgO. Microstructural analysis suggests that there is no variation in spherical elongated shape of grains with increasing concentration of MgO, where the average grain size is found to be ∼600nm. The band gap as calculated from optical absorption spectra obtained by diffuse reflectance method recorded at room temperature is tuned from 3.16 to 3.55eV. Photoluminescence spectra consist of near band edge UV emission (389nm) and defect level emission (503nm). The increase of MgO concentration leads to blue shift of UV emission peaks. The magnetic measurements conducted using SQUID at 5K temperature reveals ferromagnetism along with paramagnetic and superparamagnetic components. Saturation magnetisation (M s ) is observed to be enhanced with MgO doping. [Copyright &y& Elsevier]