Wang Limin, Tang Zhongjia, Lorenz Bernd, Guloy Arnold M
Department of Chemistry and the Texas Center for Superconductivity, University of Houston, Houston, Texas 77204-5003, USA.
J Am Chem Soc. 2008 Aug 27;130(34):11258-9. doi: 10.1021/ja803632x. Epub 2008 Aug 5.
New rare-earth silicide oxides, La10Si8O3 (1) and Ce10Si8O3 (2), were synthesized through high-temperature reactions of the pure elements under controlled oxygen atmosphere conditions. The remarkable silicides crystallize in a unique crystal structure (space group P6/mmm; a = 10.975(3) A (La) and 10.844(1) A (Ce); c = 4.680(1) A (La) and 4.561(1) A (Ce)) that features a 3-D framework of corner-shared O-centered (La/Ce)6 octahedra, reminiscent of hexagonal tungsten bronzes, with planar Si6 rings enclosed within its hexagonal channels. Band structure calculations indicate the compounds are metallic, with optimized La-Si bonds, and a benzene-like [Si6]6- anion. Compound 1 exhibits temperature independent paramagnetism. Compound 2 exhibits Curie-Weiss paramagnetism, and an antiferromagnetic ordering below 7 K.
新型稀土硅化物氧化物La10Si8O3（1）和Ce10Si8O3（2）是通过在可控氧气气氛条件下纯元素的高温反应合成的。这些引人注目的硅化物以独特的晶体结构（空间群P6/mmm；a = 10.975(3) Å（La）和10.844(1) Å（Ce）；c = 4.680(1) Å（La）和4.561(1) Å（Ce））结晶，其特征是由角共享的以O为中心的（La/Ce）6八面体构成的三维框架，让人联想到六方钨青铜，在其六方通道内包围着平面Si6环。能带结构计算表明，这些化合物是金属性的，具有优化的La-Si键和类似苯的[Si6]6-阴离子。化合物1表现出与温度无关的顺磁性。化合物2表现出居里-外斯顺磁性，并且在7 K以下呈现反铁磁有序。
