Effects of ball milling on microstructure and electrical properties of sol-gel derived (Bi_(0.5)Na_(0.5))_(0.94)Ba_(0.06)TiO_3 piezoelectric ceramics

摘要

A citrate sol-gel method was investigated for synthesizing lead-free piezoelectric compositions of (Bi_(0.5)Na_(0.5))_(0.94)Ba_(0.06)TiO_3 (BNT) and the effect of ball milling on the sintering, microstructure and electrical properties of BNT ceramics was emphasized. The thermal analysis and X-ray diffraction results show that crystalline powders with a single perovskite structure can be obtained when calcined at 600 ℃ for 3 h. The average particle size of as-calcined powder and electrical properties of sintered samples were obviously dependent on an additional ball milling. Because of well-dispersed superfine powders (～100 nm), the BNT ceramics can be well densified at temperature 50 ℃ lower than that by mixed-oxide method and conventional sol-gel method and as a result exhibit enhanced electrical properties of a piezoelectric constant d_(33) ～ 180 pC/N and a planar electromechanical coupling factor k_p ～ 0.29.