Synthesis and Characterization of a Series of Quaternary Chalcogenides BaLnMQ3 (Ln=Rare Earth, M=Coinage Metal, Q=Se or Te)

✍ Scribed by Yuting Yang; James A. Ibers

• Publisher: Elsevier Science
• Year: 1999
• Tongue: English
• Weight: 156 KB
• Volume: 147
• Category: Article
• ISSN: 0022-4596
• DOI: 10.1006/jssc.1999.8359

✦ Synopsis

The compounds BaGdAuSe 3 , BaLaCuTe 3 , BaYCuTe 3 , BaYAgTe 3 , BaLaAgTe 3 , BaYbCuTe 3 , BaGdAgTe 3 , BaNd CuTe 3 , and BaPrCuTe 3 were prepared by the reaction in a BaBr 2 /KBr 6ux at 8503C of a rare earth, a coinage-group metal, a chalcogen, and BaSe or BaTe. The unit cells of all of the compounds and the crystal structures of the 5rst four compounds were determined by single-crystal X-ray di4raction methods. With the exception of BaLaCuTe 3 , which crystallizes with four formula units in the orthorhombic space group Pnma, all of these compounds crystallize with four formula units in the orthorhombic space group Cmcm. BaLaCuTe 3 , isostructural with -BaLaCuSe 3 and Eu 2 CuS 3 (i.e., Eu 2؉ Eu 3؉ Cu ؉ (S 2؊ ) 3 ), and BaGdAuSe 3 , BaYCuTe 3 , and BaYAgTe 3 , isostructural with KZrCuS 3 , crystallize in a layered structure in which there are 2 [LnMQ 2؊ 3 ] layers separated by Ba 2؉ ions. Ln atoms are coordinated by six Q atoms at the corners of a distorted octahedron, and M atoms are coordinated by four Q atoms at the corners of a tetrahedron. The layers are formed by the connection of edgesharing octahedral chains and corner-sharing tetrahedral chains. Ba atoms are coordinated by seven Q atoms in BaLaCuTe 3 and by eight Q atoms in BaGdAuSe 3 , BaYCuTe 3 , and BaYAgTe 3 . BaNdAgTe 3 shows temperature-dependent paramagnetism. Its magnetic susceptibility follows the Curie+Weiss law. The e4ective magnetic moment of 3.4(3) B is in agreement with the theoretical value of 3.6 B for Nd 3؉ .