BiFeO3单晶的表层
Skin layer of BiFeO3 single crystals
摘要：
一个表面层（“皮肤”），这是功能和结构不同的散装被发现在单晶BiFeO3。阻抗分析表明，之前报告的T *~275 \pm 5 ^/circC处的异常对应于限制在BiFeO 3表面的相变。X射线光电子能谱学和X射线衍射作为入射角和光子波长的函数，明确地证实了皮肤的存在，估计皮肤深度为几纳米，拉长的面外晶格参数，和较低的电子密度。温度相关的X射线衍射显示，皮肤的平面外晶格参数在T * 突然变化，而大部分保留了一个非特征性的线性热膨胀。皮肤的独特性质可能在大的表面积与体积比的情况下占主导地位，例如细晶粒陶瓷和薄膜，并且应该与依赖于界面耦合的电子器件特别相关，例如交换偏置。
英文摘要：
A surface layer ("skin") that is functionally and structurally different from the bulk was found in single crystals of BiFeO3. Impedance analysis indicates that a previously reported anomaly at T* ~ 275 \pm 5 ^/circC corresponds to a phase transition confined at the surface of BiFeO3. X-ray photoelectron spectroscopy and X-ray diffraction as a function of both incidence angle and photon wavelength unambiguously confirm the existence of a skin with an estimated skin depth of few nanometres, elongated out-of-plane lattice parameter, and lower electron density. Temperature-dependent x-ray diffraction has revealed that the skin's out of plane lattice parameter changes abruptly at T*, while the bulk preserves an unfeatured linear thermal expansion. The distinct properties of the skin are likely to dominate in large surface to volume ratios scenarios such as fine grained ceramics and thin films, and should be particularly relevant for electronic devices that rely on interfacial couplings such as exchange bias.
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