AI 中文总结
研究$\mathrm{Sr}_{1 - x}\mathrm{Nd}_{x}\mathrm{CoO}_{3 - δ}$中氧非化学计量比、晶体结构及磁/电输运性质相互作用，用高分辨率衍射等方法，发现氧含量增加引发结构、磁性和输运性质转变，证实层状结构稳定由氧空位驱动。
AI 中文摘要
我们报告了对$\mathrm{Sr}_{1 - x}\mathrm{Nd}_{x}\mathrm{CoO}_{3 - δ}$（$x = 0.1, 0.2, 0.3$）中氧非化学计量比、晶体结构以及磁/电输运性质之间相互作用的系统研究。高分辨率中子粉末衍射与同步加速器X射线粉末衍射表明，增加氧含量会引发从层状$I4/mmm$（$2a_p \times 2a_p \times 4a_p$）到缺氧正交$Pmmm$（$a_p \times a_p \times 2a_p$）相的结构转变，伴有优先氧空位占据。此转变伴随着从具有弱铁磁成分的G型反铁磁到铁磁态的转变以及电阻率的急剧下降。从钴自旋态变化、吸氧时增强的Co $3d$ - O $2p$轨道重叠以及与残余氧空位和混合$\mathrm{Co}^{3 + }/\mathrm{Co}^{4 + }$价相关的磁不均匀铁磁态等方面讨论了磁和输运性质的演变。我们的发现实验证实层状“314”结构的稳定由氧空位的存在和有序性而非A位阳离子有序性驱动，而缺氧氧化化合物代表完全化学计量相之前的中间正交态。
英文摘要
We report a systematic study of the interplay between oxygen nonstoichiometry, crystal structure, and magnetic/electrotransport properties in $\mathrm{Sr}_{1-x}\mathrm{Nd}_{x}\mathrm{CoO}_{3-δ}$ ($x = 0.1, 0.2, 0.3$). High-resolution neutron powder diffraction combined with synchrotron x-ray powder diffraction reveals that increasing the oxygen content induces a structural transition from a layered $I4/mmm$ ($2a_p \times 2a_p \times 4a_p$) to an oxygen-deficient orthorhombic $Pmmm$ ($a_p \times a_p \times 2a_p$) phases with preferential oxygen-vacancy occupation. This transition is accompanied by a crossover from G-type antiferromagnetic with a weak ferromagnetic component to a ferromagnetic state, and a drastic decay in resistivity. The evolution of the magnetic and transport properties is discussed in terms of changes in the Co spin state, enhanced Co $3d$ - O $2p$ orbital overlap upon oxygen uptake, and a magnetically inhomogeneous ferromagnetic state associated with residual oxygen vacancies and mixed $\mathrm{Co}^{3+}/\mathrm{Co}^{4+}$ valence. Our findings experimentally confirm that the stabilization of the layered "314" structure is driven by the presence and ordering of oxygen vacancies rather than A-site cation ordering, whereas the oxygen-deficient oxidized compounds represent an intermediate orthorhombic state preceding fully stoichiometric phases.
Comments14 pages, 8 figures, 6 tables
