Microstructure characterization of ball-mill-prepared nanocrystalline CaCu3Ti4O12 by Rietveld method

Nanocrystalline powders of CaCu3Ti4O12 (CCTO) have been prepared by high-energy ball milling the powder mixture of CaO, CuO, TiO2 with molar ratio 1:3:4. The ball milling of powder mixture was performed in air medium for 5 min to 14 h. Microstructure characterization of all the ball-milled and unmilled powder mixtures was done by analyzing the X-ray powder diffraction data. Formation of cubic CCTO is noticed in the 2 h ball-milled powder mixture. With the progress of milling time, the cubic CCTO phase increases gradually. Complete formation of nanocrystalline CCTO was noticed within 8 h of ball milling. Formation mechanism, phase transition kinetics, structural and microstructural 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 powder mixtures by Rietveld's powder structure refinement method.