Defect chemistry and electrical properties of BiFeO3
Defect chemistry and electrical properties of BiFeO3
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DOI：
10.1039/c7tc03345a
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发表时间：
2017-10
影响因子：
6.4
通讯作者：
M. Schrade;N. Masó;A. Perejón;L. Pérez-Maqueda;A. West
中科院分区：
文献类型：
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作者：
M. Schrade;N. Masó;A. Perejón;L. Pérez-Maqueda;A. West
BiFeO3 因其丰富的功能特性而引起了广泛关注，包括磁序和铁电性的室温共存，以及最近发现的沿铁电畴壁的传导路径。在这里，通过原位测量未掺杂的、阳离子化学计量的 BiFeO3 和受体掺杂的 Bi1−xCaxFeO3−δ 陶瓷的电导率 σ 和塞贝克系数 α 作为温度和氧分压 pO2 的函数，获得了对 BiFeO3 缺陷化学和电学性质的深入了解。 Bi1−xCaxFeO3−δ 表现出 p 型传导； σ 和 α 对 pO2 的依赖性表明 Ca 掺杂剂主要由氧空位补偿。相比之下，未掺杂的 BiFeO3 显示 σ 和 α 随着 pO2 的增加而同时增加，表明电子和空穴作为几乎相同浓度的主要缺陷物质的本征行为。 σ 和 α 的 pO2 依赖性不能用单点缺陷模型来描述，而是通过本征和受主掺杂特性的组合来定量描述，这些特性归因于通过未掺杂晶粒和包含缺陷的畴壁的平行传导路径；两者都有助于 BiFeO3 中的总电荷传输。基于这个模型，我们讨论了 BiFeO3 的电荷传输机制和载流子迁移率，并表明之前的几个实验结果可以很容易地在所提出的模型中得到解释。
BiFeO3 attracts considerable attention for its rich functional properties, including room temperature coexistence of magnetic order and ferroelectricity and more recently, the discovery of conduction pathways along ferroelectric domain walls. Here, insights into the defect chemistry and electrical properties of BiFeO3 are obtained by in situ measurements of electrical conductivity, σ, and Seebeck coefficient, α, of undoped, cation-stoichiometric BiFeO3 and acceptor-doped Bi1−xCaxFeO3−δ ceramics as a function of temperature and oxygen partial pressure pO2. Bi1−xCaxFeO3−δ exhibits p-type conduction; the dependencies of σ and α on pO2 show that Ca dopants are compensated mainly by oxygen vacancies. By contrast, undoped BiFeO3 shows a simultaneous increase of σ and α with increasing pO2, indicating intrinsic behavior with electrons and holes as the main defect species in almost equal concentrations. The pO2-dependency of σ and α cannot be described by a single point defect model but instead, is quantitatively described by a combination of intrinsic and acceptor-doped characteristics attributable to parallel conduction pathways through undoped grains and defect-containing domain walls; both contribute to the total charge transport in BiFeO3. Based on this model, we discuss the charge transport mechanism and carrier mobilities of BiFeO3 and show that several previous experimental findings can readily be explained within the proposed model.