The new quaternary compounds BaLaCuQ3 (Q = S, Se) have been synthesized by the reaction of the constituent binary chalcogenides and elements at 1000°C. The crystal structures have been determined by X-ray diffraction techniques. Crystal data: BaLaCuS3-space group D162h-Pnma, M = 435.97, Z = 4, a = 11.316(2), b = 4.236(1), c = 11.724(2) Å (T = 115 K), V = 562.0(2) Å3, Rw (F2) = 0.059 for 1051 observations and 38 variables, R(F) = 0.019 for 1037 observations having F20 > 2σ,(F20); BaLaCuSe3-space group D16-Pnma, M = 576.67, Z = 4, a = 11.111(4), b = 4.293(2), c = 13.830(4) Å, (T = 115 K), V = 659.7(4) Å3, Rw(F2) = 0.129 for 1385 observations and 38 variables, R(F) = 0.050 for 1313 observations having F20 > 2σ-(F20). The BaLaCuS3 structure has a three-dimensional framework with channels that accommodate barium ions. The lanthanum atoms have mono-capped trigonal prismatic coordination and the copper atoms have tetrahedral coordination. BaLaCuSe3 crystallizes into two phases, an α phase that is isostructural with BaLaCuS3 and a layered β phase that is isostructural with Eu2CuS3. The layers, which are separated by Ba2+ ions, consist of edge-sharing octahedral chains and corner-sharing tetrahedral chains. The two structures are closely related and β-BaLaCuSe3 undergoes a phase transformation to α-BaLaCuSe3 upon mechanical grinding. The reverse phase transition occurs when α-BaLaCuSe3 is annealed at elevated temperatures.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Ceramics and Composites
- Condensed Matter Physics
- Physical and Theoretical Chemistry
- Inorganic Chemistry
- Materials Chemistry