Deng Zeyu, Wei Fengxia, Brivio Federico, Wu Yue, Sun Shijing, Bristowe Paul D, Cheetham Anthony K
Department of Materials Science and Metallurgy, University of Cambridge , 27 Charles Babbage Road, Cambridge CB3 0FS, United Kingdom.
Institute of Materials Research and Engineering , Agency for Science, Technology and Research, 2 Fusionopolis Way, Singapore.
J Phys Chem Lett. 2017 Oct 19;8(20):5015-5020. doi: 10.1021/acs.jpclett.7b02322. Epub 2017 Sep 29.
Two hybrid rare-earth double perovskites, (CHNH)KGdCl and (CHNH)KYCl, have been synthesized by a solution evaporation method and their structures determined by variable temperature single-crystal X-ray diffraction. The diffraction results show that at room temperature both perovskites adopt a rhombohedral structure with R3̅m symmetry, as found previously for (MA)KBiCl, and lattice parameters of a = 7.7704(5) Å and c = 20.945(2) Å for (MA)KGdCl and a = 7.6212(12) Å and c = 20.742(4) Å for (MA)KYCl. Both phases exhibit a rhombohedral-to-cubic phase transition on heating to ∼435 K for (MA)KYCl and ∼375 K for (MA)KGdCl. Density functional calculations on the rhombohedral phase indicate that both materials have large direct band gaps, are mechanically stable, and, in the case of (MA)KGdCl, could exhibit magnetic ordering at low temperatures.
通过溶液蒸发法合成了两种杂化稀土双钙钛矿（CHNH）KGdCl和（CHNH）KYCl，并通过变温单晶X射线衍射确定了它们的结构。衍射结果表明，在室温下，这两种钙钛矿都采用具有R3̅m对称性的菱面体结构，这与之前（MA）KBiCl的情况相同，（MA）KGdCl的晶格参数为a = 7.7704(5) Å和c = 20.945(2) Å，（MA）KYCl的晶格参数为a = 7.6212(12) Å和c = 20.742(4) Å。对于（MA）KYCl，加热至约435 K时，两个相都表现出菱面体到立方相的转变；对于（MA）KGdCl，加热至约375 K时发生该转变。对菱面体相的密度泛函计算表明，这两种材料都有较大的直接带隙，在机械上是稳定的，并且对于（MA）KGdCl而言，在低温下可能会表现出磁有序。
