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High-Pressure Synthesis of the Cobalt Pyrochlore Oxide Pb2Co2O7 with Large Cation Mixed Occupancy
Inorganic Chemistry ( IF 4.3 ) Pub Date : 2017-09-18 00:00:00 , DOI: 10.1021/acs.inorgchem.7b01646
Junye Yang,Jianhong Dai,Zhehong Liu,Runze Yu,Hajime Hojo,Zhiwei Hu,Tunwen Pi,Yunliang Soo,Changqing Jin,Masaki Azuma,Youwen Long

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 Fdm. 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 (Co0.6Pb0.4)3+2(Pb0.6Co0.4)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:

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22 ö 7型化合物的Pb 22 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。Rietveld结构分析表明,AB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 0.43+ 2(Pb0.6 Co 0.44+ 2 O 7,其中A位Co 3+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。
更新日期:2017-09-18
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