2013 Volume 121 Issue 1411 Pages 308-312
Solid-state reaction between BaCO3 and ZrO2 is the simplest method to prepare BaZrO3, which is an important refractory structural material with a very high melting point and a low chemical reactivity. However, since the solid-state formation of the BaZrO3 phase requires high calcination temperature, this method typically produces larger particles unsuitable for the sintering process than the solution methods. In this study, we investigated the reaction behavior between very fine ZrO2 (70 nm) and coarse BaCO3 (1.5–5.7 µm) and described the water vapor-assisted solid-state synthesis of BaZrO3. Nanocrystalline BaZrO3 powder (~80 nm) was obtained by solid-state reaction at 1050°C in air. The BaZrO3 formation was accelerated by water vapor-assisted reaction. The apparent activation energy for the formation reaction was calculated to be 323 ± 21 kJ/mol and 263 ± 46 kJ/mol in air and humid air with H2O of 0.5 atm, respectively. In the 1 atm water vapor atmosphere, almost single-phase BaZrO3 was obtained by calcination at 750°C.