Phase Determination & Rietveld Analysis of Cobalt-Nickel Nanocomposites in Silica Matrix by Sol-Gel Method

Abstract

Cobalt-Nickel nanocomposites having different compositions were prepared by sol-gel method using precursors like Cobalt Chloride solution, Nickel Chloride solution for Co, Ni and Tetraethyl ortho silicate (TEOS) as the silica precursor. The sample was submitted to heat treatment under nitrogen atmosphere within the temperature range 800°C to 1050°C. The changes occurring during the treatments were followed by XRDLPA analysis with the help of modified Rietveld technique. XRD data for different samples have been analyzed to determine crystallite size, microstrain and lattice parameters and to understand the size dependent co-existence of Co and Ni in different crystal structure. During heat treatments. Cobalt and Nickel Chlorides were reduced to metal nanoparticles with dextrose as reducing agent. The average particle size of Co was 49-50 nm while average particle size of Ni was 46-47 nm with increasing temperature. The value of microstrain decreases with increases of weight percent of Cobalt and Nickel at a fixed temperature. Lattice parameters undergo no significant changes with increase of weight percent of Cobalt and Nickel for a particular phase at a fixed temperature.