Synthesis of monoclinic and cubic (metastable) nanocrystalline HfO2 through the nitrate fusion technique

Abstract

Abstract For the first time it was demonstrated that nanocrystalline hafnia powders i.e. both the thermodynamically stable monoclinic phase and the metastable cubic phase could be synthesized by tailoring the nitrite to nitrate mole ratio (Φ) of the eutectic mixtures containing KNO 3 , NaNO 3 and NaNO 2 . All these nanocrystalline HfO 2 powders were characterized for their bulk density, size distribution of particles, specific surface area, carbon residue and X-ray crystallite size. All powders exhibited unimodal size distribution of particles. Transmission electron microscopy and Raman spectroscopy reaffirmed the values of crystallite size estimated through XRD investigations and the identity of the constituent phases. Grain coarsening was observed when the powders were heat treated at 1473 K.