发表机构
Institute of Energy Technologies (IET-4), Forschungszentrum Jülich GmbH; Peter Grünberg Institute (PGI-1), Forschungszentrum Jülich GmbH; Department of Materials Science and Engineering and Materials Research Institute, The Pennsylvania State University; Institute of Physics, University of Silesia; Marian Smoluchowski Institute of Physics, Jagiellonian University（尤利希研究中心能源技术研究所; 尤利希研究中心彼得·格林贝格研究所; 宾夕法尼亚州立大学材料科学与工程系及材料研究所; 西里西亚大学物理研究所; 雅盖隆大学马里安·斯莫卢霍夫斯基物理研究所）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
该研究探究热氧化对BaTiO$_3$单晶的影响，发现表面纳米级相分离形成三明治结构，屏蔽极化并降低铁电响应，导电性沿位错细丝传导，氧化可将晶体从金属态转为半导体态且无法还原恢复。
AI 中文摘要
我们研究了热氧化对BaTiO$_3$单晶的影响。结果表明，即使在高达1000℃的中等温度下，也会发生复杂的偏析机制，包括富钡化合物向表面迁移，并在表面形成不均匀分布的BaO纳米晶体。由此，表面层较深区域的钡元素被耗尽，变为富TiO$_2$相。表面层形成了三明治状结构，表现出可测量的电动势和自极化，这反过来会屏蔽极化并降低整体铁电响应。导电性也受到表面区域不可逆偏析效应的强烈影响：原始晶体可转变为金属态，而氧化会诱导其呈现半导体特性，且后续还原无法使其恢复金属态。纳米级分析表明，导电性通过沿位错形成的细丝传导，即使在中等温度下，由于钡和氧的优先管道扩散，这些细丝的局部化学组成会在还原和氧化过程中发生变化，从而决定了整个样品的电学行为。
英文摘要
We investigate the effect of thermal oxidation on BaTiO$_3$ single crystals. Our results reveal that, even at moderate temperatures of up to 1000 °C, complex segregation mechanisms occur involving the movement of Ba-rich compounds to the upper surface, where they form inhomogeneously distributed BaO nanocrystals. As a result, deeper regions of the surface layer become depleted in Ba and become TiO$_2$-rich. A sandwich-like structure evolves in the surface layer, exhibiting a measurable electromotive force and self-polarization. This, in turn, screens the polarization and diminishes the global ferroelectric response. The conductivity is also strongly influenced by the irreversible segregation effects in the surface region. An as-received crystal can be transformed into a metallic state, while oxidation induces semiconducting properties and prevents a return to the metallic state upon subsequent reduction. Nanoscale analysis demonstrates that the conductivity is channeled to filaments forming along dislocations, whose local chemical composition changes upon reduction and oxidation even at moderate temperatures due to preferential Ba and O pipe diffusion thus determining the electric behavior of the whole sample.
