Syntheses, Structure, Magnetism, and Optical Properties of the Ordered Mixed-Lanthanide Sulfides -LnLn'S3 (Ln = La, Ce; L

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• 作者：Geng Bang Jin ; Eun Sang Choi ; Robert P. Guertin ; James S. Brooks ; Travis H. Bray ; Corwin H. Booth ; Thomas E. Albrecht-Schmitt
• 刊名：Chemistry of Materials
• 出版年：2007
• 出版时间：February 6, 2007
• 年：2007
• 卷：19
• 期：3
• 页码：567 - 574
• 全文大小：423K
• 年卷期：v.19,no.3(February 6, 2007)
• ISSN：1520-5002

文摘

-LnLn'S₃ (Ln = La, Ce; Ln' = Er, Tm, Yb) have been prepared as dark red to black single crystalsby the reaction of the respective lanthanides with sulfur in a Sb₂S₃ flux at 1000 ntities/deg.gif">C. This isotypic seriesof compounds adopts a layered structure that consists of the smaller lanthanides (Er, Tm, and Yb) boundby sulfide in six- and seven-coordinate environments that are connected together by the larger lanthanides(La and Ce) in eight- and nine-coordinate environments. The layers can be broken down into three distinctone-dimensional substructures containing three crystallographically unique Ln' centers. The first of theseis constructed from one-dimensional chains of edge-sharing [Ln'S₇] monocapped trigonal prisms that arejoined to equivalent chains via edge sharing to yield ribbons. There are parallel chains of [Ln'S₆] distortedoctahedra that are linked to the first ribbons through corner sharing. These latter units also share cornerswith a one-dimensional ribbon composed of parallel chains of [Ln'S₆] polyhedra that edge-share both inthe direction of chain propagation and with adjacent identical chains. Magnetic susceptibility measurementsshow Curie-Weiss behavior from 2 to 300 K with antiferromagnetic coupling and no evidence formagnetic ordering. The _p values range from -0.4 to -37.5 K, and spin-frustration may be indicated forthe Yb-containing compounds. All compounds show magnetic moments substantially reduced from thosecalculated for the free ions. The optical band gaps for -LaLn'S₃ (Ln' = Er, Tm, Yb) are approximately1.6 eV, whereas -CeLn'S₃ (Ln' = Er, Tm, Yb) are approximately 1.3 eV.