Preparation of BaZrxTi1−xO3 by the hydrothermal process from peroxo-precursors

Crystalline BaZrxTi1−xO3 (BZT) powders were synthesized through a hydrothermal reaction by using amorphous BaZrxTi1−x-peroxo-hydroxide. BaZrxTi1−x-peroxo-hydroxide precursors were prepared by coprecipitatation of BaCl2, ZrOCl2, TiOCl2 and H2O2 aqueous solution added to ammonium solution. Additional Ba(OH)2 was used as a mineralizer. This processing method provided a simple low temperature route for producing BZT fine powders, which could also be extended to other systems. It was found that phase-pure BZT powders with a cubic perovskite structure were synthesized under mild hydrothermal conditions (100–130 °C, ≤1.5 MPa). Ultra-fine BZT powders having the BET surface area of 30 m2/g were formed. The BZT ceramics sintered at a temperature as low as 1150 °C for 1 h had 93% of theoretical density. The higher Zr content leaded to a higher dielectric constant at room temperature and a more diffuse ferroelectic-to-paraelectric transition, which resulted in a reduced temperature dependency of the dielectric constant for the BaZr0.2Ti0.8O3 ceramic.