发表机构
University of Pittsburgh（匹兹堡大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究以KSb3Mn9O19为模型，发现Cr3+在M型六方铁氧体中显著偏好Mn Kagome亚晶格，并通过晶体场、化学键和应变解释该选择性，为控制阳离子分布提供化学设计原则。
AI 中文摘要
阳离子分布对晶体氧化物性质的确定起着关键作用。因此，理解控制阳离子分布的化学因素对于合理设计阳离子有序材料至关重要，特别是对于结构无序会强烈影响磁基态的阻挫磁体。本文以首个Mn基M型六方铁氧体KSb3Mn9O19为模型体系，研究了被广泛研究的M型六方铁氧体结构中阳离子分布的起源与演化。利用粉末和单晶X射线衍射、电子显微镜以及能量色散X射线光谱，系统考察了Cr3+掺杂系列KSb3(Mn1-xCrx)9O19。Cr3+对Mn Kagome亚晶格表现出显著偏好，同时伴随Mn空位的演化以及邻近位点上Mn3+/Sb3+的无序。对局域配位环境及其随Cr含量变化的分析表明，晶体场效应、化学键合和局域结构应变共同控制着这种位点选择性。Cr掺杂化合物的磁性质与未掺杂母体化合物表现出相似行为，但在最高Cr浓度下出现掺杂诱导的自旋玻璃态，这一点得到了热容测量的支持。这些结果建立了M型六方铁氧体中阳离子位点分布与选择的化学图景，并展示了在一个晶体学位点上的取代如何引发跨相邻亚晶格的耦合重分布和无序。此外，本工作确立了局域配位化学作为理解和最终控制复杂氧化物中阳离子分布的途径，为结构明确的阻挫磁性材料提供了化学设计原则。
英文摘要
Cation distribution plays a critical role in determining the properties of crystalline oxides. Understanding the chemical factors that govern cation distribution is therefore essential for the rational design of cation-ordered materials, particularly frustrated magnets in which structural disorder can strongly affect the magnetic ground state. Here, we investigate the origin and evolution of cation distribution in the extensively studied M-type hexaferrite structure using the first Mn-based M-type hexaferrite, KSb3Mn9O19, as a model system. A systematic Cr3+-doped series, KSb3(Mn1-xCrx)9O19, was examined using powder and single-crystal X-ray diffraction, electron microscopy, and energy-dispersive X-ray spectroscopy. Cr3+ exhibits a pronounced preference for the Mn Kagome sublattice, accompanied by the evolution of Mn vacancies and Mn3+/Sb3+ disorder on neighboring sites. Analysis of the local coordination environments and their evolution with Cr content suggests that crystal-field effects, chemical bonding, and local structural strain collectively govern this site selectivity. The magnetic properties of the Cr-doped compounds show similar behaviors as the undoped parent compound, other than the doping-induced spin-glass state at the highest Cr concentration, supported by heat capacity measurements. These results establish a chemical picture of cation site distribution and selection in M-type hexaferrites and demonstrate how substitution at one crystallographic site can induce coupled redistribution and disorder across neighboring sublattices. Moreover, this work establishes local coordination chemistry as a route toward understanding and ultimately controlling cation distribution in complex oxides, providing chemical design principles for structurally well-defined frustrated magnetic materials.
Comments36 pages, 9 figures, 6 tables
