Hemaunt Kumar

Effect of sintering temperature on the structural properties of cobalt ferrite nanoparticles

The nanocrystalline CoFe2O4 was prepared by nitrate route at the sintering temperature of 300, 500, 700 and 900°C. The X-ray diffraction (XRD) patterns of all the samples show the single phase spinel structure of nanoparticles. The crystallite sizes vary from 9 to 61 nm as the sintering temperature increases from 300 to 900°C. The FTIR spectra of cobalt ferrite were recorded in the range of 400 to 5,000 cm–1 at room temperature. FTIR spectra of the cobalt ferrite nanoparticles show no residual organic compounds and confirm the formation of the organic free cobalt ferrite nanoparticles above the sintering temperature 500°C. The assigned Raman modes are the characteristics of the spinel structure of the synthesised samples which change slightly with different sintering temperature. The Raman modes of cobalt ferrite nanoparticles at 300°C temperature follow the phonon confinement as the particle size is ~9 nm.

Magnetic anomalies in specific heat and dielectric properties of multiferroic GdMnO3

The specific heat and dielectric properties of multiferroic GdMnO3 synthesized by modified sol-gel technique has been investigated. GdMnO3 crystallized in orthorhombic perovskite structure. X-ray diffraction was used to investigate the structural information. Morphology has been investigated by field emission scanning electron microscope and the average grain size is found to be ∼ 552 nm. Magnetic anomalies have been observed in specific heat and dielectric properties of GdMnO3.