(PbBa)(Zr,Sn,Ti)O_3反铁电/弛豫型铁电相界陶瓷的相变与介电、热释电性质

The phase transformation, dielectric and pyroelectric properties of (PbBa)(Zr,Sn,Ti)O_3 solid solutions with compositions near AFE/RFE phase boundary

通过对 (Pb0 87Ba0 1 La0 0 2 ) (Zr0 6 TixSn0 4 -x)O3(0 0 4≤x≤ 0 2 0 )固溶体的介电和偏压热释电性质的研究发现 ,当Ti含量 0 0 4≤x≤ 0 0 7时 ,材料是反铁电四方相 ,而当 0 0 9≤x≤ 0 2 0时 ,材料向弛豫型铁电体转化 .在温度 Ti含量相图中 ,x =0 0 9附近形成了反铁电 铁电 顺电三相共存点 (Ttr) .该点的相变温度最底 ;对于 0 0 4≤x≤ 0 0 7的反铁电四方相 ,低温下呈现介电弛豫特征 ,并可被外电场诱导为亚稳铁电态 ,温度升高时 ,亚稳铁电→反铁电相变 ,反铁电→顺电相变引起两个热释电流峰 ,偏置电场下峰位和峰强均发生移动 ,在温度 电场相图中也形成了铁电 反铁电 顺电三相点 .从复杂化合物纳米相分离的观点和晶格动力学出发 ,讨论了相变与电学性能随Ti含量 (x)和外电场(E)变化的物理机理 .

Ba modified lead zircono stanno titanate (Pb 0 87 La 0 02 Ba 0 1 )(Zr 0 6 Sn 0 4- x ,Ti x )O 3(0 04≤ x ≤0 20)solid solutions were investigated by measurements of dielectric spectroscopy and pyroelectric current. It is found that specimens with 0 04≤ x ≤0 07 are in antiferroelectric tetragonal phase (AFE t), but specimens with 0 09≤ x ≤0 20 are ferroelectric relaxors(RFE). Therefore, there is a new AFE/RFE phase boundary. In the temperature Ti content( x ) phase diagram, FE AFE PE(paraelectric phase) triple phase point with the lowest phase transition temperature has been observed for the composition of x =0 09. For AFE t ceramics ( x ≤0 07), a particular diffuse phase transition and polar relaxor behaviour is observed at low temperatures, within which AFE t could be induced to a metastable ferroelectric state(FE in ) by applying an external electric field. FE in was transformed to AFE t and PE states separately with the increase of temperature, resulting in two pyroelectric peaks. Furthermore, FE AFE PE triple phase point has been observed in the phase diagram of temperature electric bias field ( E ). Finally, the experimental results have been well explained on lattice dynamics, considering nano size phase separation in complex compounds.