The Fe²⁺/Fe³⁺ charge order (CO) in LuFe₂O₄ has been examined by Mössbauer quadrupole effect. The stoichiometric single crystal of LuFe₂O₄ was used to measure the paramagnetic spectrum at 282 K. The spectrum was analyzed by assuming the CO monoclinic structure (space group C2/m) with four inequivalent Fe sites, among which two are occupied by Fe³⁺ and other two are occupied by Fe²⁺. The obtained quadrupole parameters, quadrupole splitting QS and the intensity ratio of the two absorption lines I(±3/2)/I(±1/2), coincide well with those calculated from the crystal structure. On the other hand, the parameters obtained by assuming other two crystal structures previously proposed, the hexagonal structure with a single Fe site (\(R\bar{3}m\)) and the monoclinic structure with a single Fe site (C2/m), are found to be inconsistent with the calculated ones. These results indicate that the CO monoclinic structure is most probable among the structural models proposed so far from the viewpoint of the Mössbauer quadrupole effect.

中文翻译：

---

Mössbauer四极效应检查混合价态LuFe2O4中的电荷序

通过穆斯堡尔四极效应研究了LuFe ₂ O _4中的Fe ²⁺ / Fe ³⁺电荷级（CO）。用化学计量的LuFe ₂ O ₄单晶测量282 K时的顺磁光谱。该光谱通过假设具有四个不等价的Fe位点的CO单斜晶结构（空间群C 2 / m）进行分析，其中两个被Fe占据。 Fe ³⁺和另外两个被Fe ²⁺占据。获得的四极参数，四极分裂QS和两条吸收线的强度比I（±3/2）/ I（±1/2），与根据晶体结构计算得出的结果非常吻合。另一方面，通过假设先前提出的其他两个晶体结构（具有单个Fe位置的六边形结构）获得的参数（\（R \ bar {3} m \））和具有单个Fe位置（C 2 / m）的单斜结构，发现与计算的不一致。这些结果表明，从Mössbauer四极效应的角度来看，到目前为止，在提出的结构模型中最有可能采用的是CO单斜结构。