Temperature-dependent vibrational spectroscopic and X-ray diffraction investigation of nanosized nickel chromite

The nanocrystalline nickel chromite (NiCr2O4) with particle size of similar to 20 nm was prepared by auto-combustion method. The nanocrystals were characterized by powder X-ray diffraction, vibrational spectroscopy and magnetic measurements. The expected structural phase transitions (cubic-tetragonal-orthorhombic) were studied by methods of temperature-dependent X-ray powder diffraction and vibrational spectroscopy. The evolution of the Raman spectra and X-ray diffraction patterns collected from 350 K down to 4 K confirmed the cubic-to-tetragonal distortion at similar to 250 K, whereas the tetragonal-to-orthorhombic transition was not confirmed in the nanocrystalline sample. (C) 2014 Elsevier B.V. All rights reserved.