Feng Hai L, Kang Chang-Jong, Deng Zheng, Croft Mark, Liu Sizhan, Tyson Trevor A, Lapidus Saul H, Frank Corey E, Shi Youguo, Jin Changqing, Walker David, Kotliar Gabriel, Greenblatt Martha
Department of Chemistry and Chemical Biology, Rutgers, the State University of New Jersey, 123 Bevier Road, Piscataway, New Jersey 08854, United States.
Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.
Inorg Chem. 2021 Apr 5;60(7):4424-4433. doi: 10.1021/acs.inorgchem.0c03124. Epub 2021 Mar 11.
A polycrystalline sample of TlIrO was synthesized by high-pressure and high-temperature methods. TlIrO crystallizes in the cubic pyrochlore structure with space group 3̅ (No. 227). The Ir oxidation state is confirmed by Ir- X-ray absorption near-edge spectroscopy. Combined temperature-dependent magnetic susceptibility, resistivity, specific heat, and DFT+DMFT calculation data show that TlIrO is a Pauli paramagnetic metal, but it is close to a metal-insulator transition. The effective ionic size of Tl is much smaller than that of Pr in metallic PrIrO; hence, TlIrO would be expected to be insulating according to the established phase diagram of the pyrochlore iridate compounds, AIrO. Our experimental and theoretical studies indicate that TlIrO is uniquely different from the current AIrO phase diagram. This uniqueness is attributed primarily to the electronic configuration difference between Tl and rare-earth ions, which plays a substantial role in determining the Ir-O-Ir bond angle, and the corresponding electrical and magnetic properties.
通过高温高压法合成了TlIrO多晶样品。TlIrO以空间群为3̅（编号227）的立方烧绿石结构结晶。通过Ir-X射线吸收近边光谱法确定了Ir的氧化态。结合变温磁化率、电阻率、比热以及DFT+DMFT计算数据表明，TlIrO是一种泡利顺磁金属，但它接近金属-绝缘体转变。在金属PrIrO中，Tl的有效离子尺寸比Pr小得多；因此，根据已建立的烧绿石铱酸盐化合物AIrO的相图，预计TlIrO是绝缘的。我们的实验和理论研究表明，TlIrO与当前的AIrO相图有独特的不同。这种独特性主要归因于Tl与稀土离子之间的电子构型差异，这在确定Ir-O-Ir键角以及相应的电学和磁学性质方面起着重要作用。
