BARIUM TITANATE PROPERTIES ENHANCED BY ATTRITION MILLING

Abstract

Barium titanate powder was prepared by soft chemical process from polymeric precursors (modified Pechini process). The obtained BT powder was nanosized with primary particles ~ 74 nm, but factor of agglomeration (Fagg) pointed on existence of agglomerates ~ 6 �����m. It is well known that agglomerates could influence on setback of materials structure and properties. In order to de-agglomerate nanopowder and to improve BT properties, attrition milling was performed. Barium titanate powder was treated in attrition mill with zirconia media for 1h in 2% polyacrylic acid. Milling induced reduction of agglomerates in size and number. Characterization of both starting (BT) and milled (BTA) powders was performed. The comparison of obtained results showed enhancement of powders properties generated by attrition milling. To investigate the effect of milling on electrical properties of ceramics, both BT powders were uniaxially pressed and sintered at 1300°C for 8 h in air. The density of BTA ceramics was 95 % of theoretical value and 90 % of BT. Temperature dependence of relative permittivity showed three structural transitions characteristic for ferroelectric BT ceramics. The temperature transition from ferroelectric to paraelectric was found to be at 120°C for BT and 122°C for BTA. Dielectric constant value was around 6700 for BTA which is much higher value in comparison with non-treated BT where permittivity was 1340. Dielectric losses were below 0.03 for both BT ceramics.