The critical crystallite size for the cubic (c-) to tetragonal (t-) phase transformation of ultrafine BaTiC>3 crystallites was examined. Crystallites were prepared by calcination of barium titanyl oxalate tetrahydrate (BTOT) at various temperatures as to obtain crystallites with different sizes. The c-BaTi03 crystallite which is thermodynamically considered as a high-temperature form can exist at room temperature if the crystallite is smaller than certain size. The critical size for the c—M; phase transformation is ˜30 nm. The size may become larger if the crystallite suffers higher lattice strain which can be induced by different powder preparation methods.
All Science Journal Classification (ASJC) codes
- Physics and Astronomy(all)