Microstructure characterization and phase transformation kinetics of ball-milled prepared nanocrystalline Zn2TiO4 by Rietveld method

Both the normal and inverse Zn2TiO4 spinel phases have been synthesized by ball milling the mixture of ZnO and anatase TiO2 (2:1 mol%) in a high-energy planetary ball mill. Microstructure characterization of unmilled and ball-trtilled materials has been made by employing the Rietveld's powder structure refinement methodology using X-ray powder diffraction data. Phase transformation kinetics of ball-milled composites has been studied in terms of relative abundance of phases at different milling duration. Particle size and r.m.s. lattice strain values of ZnO, and spinel phases are found to be anisotropic and that of anatase, rutile and srilankite polymorphic TiO2 phases are isotropic in nature. It seems that the normal Zn2TiO4 has been formed from the ZnO-anatase TiO2 solid solution and its inverse counterpart from ZnO-srilankite TiO2 solid solution. A high degree of anisotropy in r.m.s. lattice strain along the dense (0 0 2) plane of hexagonal ZnO lattice suggests that the Zn atoms on this lattice plane is preferably substituted by the Ti atoms. (C) 2003 Elsevier B.V. All rights reserved.