Effect of Ca addition on Grain Size and Crystal Phase of Barium Titanate Nanopowders

概要

論文の詳細を見る
The effect of 2.5 at. % Ca addition on the grain size and crystal lattice of hydrothermally produced barium titanate nanopowders was studied by field-emission transmission electron microscopy (FE-TEM). The fabrication of the nanopowders involved the heat treatment of Ba0.975Ca0.025TiO3 and BaTiO3 powders. The grain growth of Ba0.975Ca0.025TiO3 particles is inhibited by the Ca coating. A pore region is observed in both types of particles and the average size of the pores depends on the calcination temperature. In addition, the crystal structure of the nanoparticles was investigated with high-resolution transmission electron microscopy (HRTEM) and X-ray diffraction (XRD). These methods show that both powders have a crystalline structure with lattice planes typical for a perovskite structure. The lattice shrinkage is explained by Ca substitution at the Ba atomic positions in the unit cell of barium titanate, and the tetragonal lattice distortion is accounted for by Ca substitution at the Ti sites in the perovskite structure. X-ray absorption fine structure (XAFS) analysis shows that the local atomic structures around Ti in Ba0.975Ca0.025TiO3 and BaTiO3 particles are more highly ordered compared with pure single-crystalline BaTiO3.
Published by the Japan Society of Applied Physics through the Institute of Pure and Applied Physicsの論文
2006-10-15