Bilal Hamid Bhat

Effect of Annealing Temperature on Different Physical Properties of Sr0.5la0.5Mg0.5Fe11.5o19 Hexaferrite

The influence of annealing on different physical properties of La0.5Mg0.5Sr0.5Fe11.5O19 hexaferrites prepared by the citrate-precursor method is presented in this study. The effects of temperature on the physical properties properties of the synthesized hexaferrites have been investigated using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Scanning Electron Miscroscopy (SEM) and Vibrating Sample Magnetometer (VSM). The XRD study shows the formation of hexagonal structure with grain size lying between 23.86 nm and 56.12 nm. FTIR was used to study functional groups associated with the material. A decrease in saturation magnetization (Ms), and increase in Coercivity (HC) is observed with increase in temperature. Also, anisotropy constant was calculated by using Law of Approach to saturation and is well agreement with the literature.

Dielectric and conducting behaviour of polycrystalline holmium octa-molybdate

Polycrystalline holmium octa-molybdate spherulites have been obtained by using gel diffusion technique and characterized by different physio-chemical techniques. The surfaces of these spherulites are composed of nano-rod with an average diameter of about 80 nm. At room temperature the initial crystal structure is triclinic, space group P1. Thermal studies suggested a phase transition occurring in holmium octa-molybdate crystals at about 793 K. The electrical properties of the system have been studied as a function of frequency and temperature in the ranges of 20 Hz–3 MHz and 290–570 K, respectively. A giant dielectric constant and two loss peaks have been observed in the permittivity formalism. The conducting behaviour of the material is also discussed. The conductivity was found to be 1572 μ Ω−1 m−1 at room temperature and 3 MHz frequency. The conductivity of the polycrystalline material was attributed to the fact that it arises due to the migration of defects on the oxygen sub-lattice. Impedance studies were also performed in the frequency domain to infer the bulk and grain boundary contributions to the overall electric response of the material. The electrical responses have been attributed to the grain, grain-boundary, and interfacial effects.