Preparation of nanocrystalline microwave dielectric Zn2TiO4 and ZnTiO3 mixture and X-ray microstructure characterization by Rietveld method

Nanocrystalline microwave dielectrics ZnTiO3 and Zn2TiO4 (spinel) phase have been prepared by high-energy ball milling the powder mixture of ZnO and anatase (a)-TiO2. Ball milling of equimolar powder mixture of ZnO and a-TiO2 is continued up to 6 h with some intermediate milling steps. Microstructure of all the samples is characterized by Reitveld's structure refinement method using X-ray powder diffraction data. Mixture of nanocrystalline ZnTiO3 and Zn2TiO4 is noticed to form after 6 h of ball milling. Within 30 min of milling formation of Zn2TiO4 is noticed in the X-ray diffraction pattern whereas the formation of ZnTiO3 starts after 2 h of ball milling. The formation mechanism, phase transition kinetics, structure and microstructure changes in terms of lattice imperfections and relative phase abundances of individual phases have been estimated from the analysis of X-ray powder diffraction data of unmilled and ball-milled samples by Rietveld's powder structure refinement method.