Pronounced Site Preference in Cr-Doped Mn-Based M-Type Hexaferrites and Its Chemical Origins

Dylan Correll; Susheng Tan; Evan Wang; Xin Gui

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arXiv · 2609.37720

Pronounced Site Preference in Cr-Doped Mn-Based M-Type Hexaferrites and Its Chemical Origins

Dylan Correll·Susheng Tan·Evan Wang·Xin Gui

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Abstract

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.

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Dylan Correll, Susheng Tan, Evan Wang, Xin Gui. 2026-09-29. Pronounced Site Preference in Cr-Doped Mn-Based M-Type Hexaferrites and Its Chemical Origins. https://arxiv.org/abs/2609.37720

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