复合离子(Sr1/3Nb2/3)^4+对0.82BNT-0.18BKT陶瓷结构与性能的调控

Structure and Electrical Properties of 0.82BNT-0.18BKT Ceramics Modified by(Sr 1/3 Nb 2/3)^4+Complex Ions

采用传统固相反应烧结制备了0.82Bi0.5Na0.5TiO3-0.18Bi0.5K0.5Ti(1-x)(Sr1/3Nb2/3)xO3(BNKT-xSN)无铅陶瓷,研究了B位复合离子(Sr 1/3-Nb 2/3)4+掺杂量对BNKT-x SN陶瓷微观结构和铁电、介电、储能、应变性能的影响。研究表明:复合离子(Sr 1/3 Nb 2/3)^4+固溶到晶格中时,引起晶格畸变,而且极大降低了晶粒尺寸;(Sr 1/3 Nb 2/3)^4+的引入破坏了体系内占主导地位的长程铁电畴,电滞回线向细长形转变,铁电相逐渐向弛豫态转变;场致应变表明在x=0.20时,最大的正向应变为0.16%,d 33*表现出与单极应变量一样的变化趋势,最大值为277 pm/V;介电频谱表明当x<0.20时,BNKT-xSN陶瓷呈弱铁电相,当x≥0.25时则弛豫相为主导相,而当x=0.20时铁电-弛豫相共存。

The 0.82Bi 0.5 Na 0.5 TiO 3-0.18Bi 0.5 K 0.5 Ti(1-x)(Sr 1/3 Nb 2/3)x O 3 lead-free ceramics are fabricated by the traditional solid state reaction.The effects of B-site(Sr 1/3 Nb 2/3)4+complex ions on the microstructure,ferroelectric,dielectric,energy storage,and strain properties of BNKT-x SN ceramics are investigated.The results show that(Sr 1/3 Nb 2/3)4+complex ions dissolves into the lattice of BNKT matrix,and results in lattice distortion.The grain size of BNKT-x SN ceramics is greatly decreased by introducing(Sr 1/3 Nb 2/3)4+complex ions.The long term ferroelectric order is disturbed by(Sr 1/3 Nb 2/3)4+complex ions,the hysteresis loops transform from typical rectangle to slimmer shape,and the ferroelectric state gradually changes to the relaxation state.The electric field-induced strain shows that the maximum forward strain of 0.16%is obtained at x=0.20,the d 33*shows the similar behavior as the unipolar stain and achieves the maximum value of 277 pm/V.The temperature-dependent dielectric spectrum shows that BNKT-x SN ceramics are weakly ferroelectric state at x<0.20,dominates by relaxation state at x≥0.25,and exists the coexistence of ferroelectric state and relaxation state at x=0.20.