文章基本信息

标题：Origin of anomalous giant dielectric performance in novel perovskite: Bi_0.5−xLa_xNa_0.5−xLi_xTi_1−yM_yO₃ (M = Mg²⁺, Ga³⁺)
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作者：Xiao Liu ; Huiqing Fan ; Jing Shi 等
期刊名称：Scientific Reports
电子版ISSN：2045-2322
出版年度：2015
卷号：5
DOI：10.1038/srep12699
出版社：Springer Nature
摘要：Dielectric properties and dielectric relaxation behaviors of A/B sites co-substituted Bi_0.5Na_0.5TiO₃ perovskite-type ferroelectrics are reported. The Bi_{0.5− x}La_xNa_{0.5− x}Li_xTi_{1− y} M _yO₃ ( M = Mg²⁺, Ga³⁺) exhibits anomalous giant dielectric permittivity ( ε ’) of ~10⁵ under a heterogeneous constitution with easily discernible grain and grain boundary conductivity. The lone pairs substitution theory as well as extrinsic disorders are used to clarify the significant structural evolution and the origin of the dielectric performance. A bigger free volume promotes the anomalous relaxation between oxygen sites, and the polarization direction on the nanoscale deviates from the average polarization direction at its ferroelectric state. Furthermore, no obvious phase transition indicates the considerable static substitutional disorder at the Bi/Na sites, which facilitates delocalized conduction of oxygen ions in the intermediate temperature range.