The novel A₂B₂O₇-type compound Pb₂Co₂O₇ was synthesized at 8 GPa and 1673 K. Synchrotron X-ray diffraction shows a cubic pyrochlore structure with space group Fd3̅m. Rietveld structural analysis reveals a large cation mixed occupancy at both A and B sites by about 40%, the greatest value found in the pyrochlore family. In combination with the X-ray absorption spectroscopy results, the specific chemical composition and charge states are determined to be (Co_0.6Pb_0.4)³⁺₂(Pb_0.6Co_0.4)⁴⁺₂O₇, in which both the A-site Co³⁺ and the B-site Co⁴⁺ are low-spin. Due to the tetrahedral geometric frustration effects as well as the random Co⁴⁺ and Pb⁴⁺ distribution at the B site, spin glassy behavior is well observed following the conventional critical slowing down feature in Pb₂Co₂O₇.

中文翻译：

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大阳离子混合占有率高压合成四氯氧化钴Pb ₂ Co ₂ O _7的研究

该新型甲₂乙₂ ö ₇型化合物的Pb ₂共₂ ö ₇在为8GPa和1673 K.同步加速器X射线衍射显示了立方烧绿石结构，空间群合成的Fd 3米。Rietveld结构分析表明，A和B位置的阳离子混合占有率均高达40％，这是在烧绿石家族中发现的最大值。结合X射线吸收光谱法的结果，确定特定的化学成分和电荷态为（Co _0.6 Pb _0.4）³⁺ ₂（Pb_0.6 Co _0.4）⁴⁺ ₂ O ₇，其中A位Co ³⁺和B位Co ⁴⁺均为低自旋。由于四面体的几何挫折效应以及B位置处的随机Co ⁴⁺和Pb ⁴⁺分布，遵循Pb ₂ Co ₂ O _7中的常规临界减速特性，可以很好地观察到自旋玻璃态行为。