Improvement of barium titanate properties induced by attrition milling

Barium titanate powder was prepared by soft chemical process from polymeric precursors (modified Pechini process). The synthesized barium titanate (BT) powder was nanosized and the factor of agglomeration (F_agg) pointed the existence of agglomerates. In order to de-agglomerate nanopowder and to enhance BT properties the attrition milling was performed. The milled powder (BTA) possessed smaller particles and the size and number of agglomerates was significantly reduced. To investigate the effect of milling on improvement of ceramics electrical properties, both BT and BTA powders were uniaxially pressed and sintered at 1300 °C for 8 h in air. The temperature dependence of relative permittivity showed three structural phase transitions for ferroelectric barium titanate ceramics. The dielectric constant at Curie temperature was ～6700 for BTA which is much higher than 1340, obtained for non-treated BT. The dielectric losses were below 0.04 in both BT ceramics. At higher temperatures the analysis of impedance measurements showed the presence of both grain interior and grain boundary effects. Much higher grain and grain boundary resistivities were obtained for the BTA ceramics.