Dielectric and ferroelectric behaviors of BaTiO_3-(K_(1/4)Bi_(3/4))(Mg_(1/4)Ti_(3/4))O_3 ceramics

摘要

Perovskite ferroelectric ceramics of (1-x)BaTiO_(3-x)(K_(1/4)Bi_(3/4))(Mg_(1/4)Ti_(3/4) [(1 -x)BT-xKBMT, x=0.06, 0.1, and 0.14] were synthesized via solid-state reaction method. Dielectric constant maximum ε_m of BT-KBMT ceramics declines with KBMT content. ε(T) peak temperature T_m (402 K) is close to T_c (403 K) of the parent BT for composition 0.94BT-0.06KBMT, and decreases to 382 K for 0.9BT-0.1KBMT. Dielectric behaviors of the two compositions exhibit features of ferroelectrics with diffuse phase transition. A high-field linear polarization behavior was observed in the two compositions around temperature range of the e(T) peak summit. e(T) peak of 0.86BT-0.14KBMT is saddle-backed. The high turning temperature T_(m1) fixes around 384 K, and is the Burns temperature T_B of the composition. The low turning point T_(m2) is 326 K at 100 Hz and highly frequency dependent. The dielectric anomaly of 0.86BT-0.14KBMT around T_(m2) is associated with diffuse transitions from ferroelectric macrodomains to microdomains, polar nanoregions and paraelectric states.