In-situ high-temperature X-ray diffraction studies of non-stoichiometric Ni–Zr substituted barium hexagonal ferrites prepared by citrate precursor route

The mechanism of evolution of hexaferrite has been studied in non-stoichiometric Ni–Zr substituted barium ferrites using the technique of in-situ high-temperature X-ray diffraction. Vacancies in the lattice and a small excess of Ba2+ have been found to aid phase formation at lower temperatures. Furthermore, the mechanism of hexaferrite formation is different in non-stoichiometric compositions as compared to the stoichiometric samples. The thermal expansion data shows lowering of the thermal expansion coefficients due to relaxing of bonds in non-stoichiometric compositions.