The crystal structure of Cu₂CdGeS₄ and other quaternary normal tetrahedral structure compounds

Abstract

Single crystal diffraction methods have been used to solve the crystal structure of Cu2CdGeS4: space group Pmn21 (C7v); a=7.692, b=6.555, c= 6.299 ,~i. Five other compounds of general composition 122464 also show superstructures either of wurtzite or of sphalerite, while the twenty investigated 122364 compounds have no ordered cation arrangement producing simple wurtzite or zincblende diffraction patterns.The problems in the determination of quaternary zincblende or wurtzite related superstructures in general are discussed.

Refinement of the crystal structures of Cu3PS4and Cu3SbS4and a comment on normal tetrahedral structures

“…[12]. As discussed by Parthé et al [13] the ordering of the cations in the respective tetragonal and orthorhombic structures is very similar for the compounds under discussion. Thus, the same Wyckoff positions are occupied in famatinite and in stannite.…”

The system Cu3AsS4–Cu3SbS4and investigations on normal tetrahedral structures

“…An ordered distribution causes a reduction of symmetry, e.g. leading to a tetragonal instead of a cubic cell for Cu 3 SbS 4 (famatinite), whereas an orthorhombic cell instead of a hexagonal cell results for Cu 3 AsS 4 (enargite) [2]. An even lower symmetry has been observed in some other cases.…”

Tl4Ge4Se10, ein Thallium(1)selenogermanat mit adamantananalogem Anion [Ge4Se10]4- / Tl4Ge4Se10, a Thallium(I) Selenogermanate with the Adamantane-Like Anion [Ge4Se10]4-

“…Obwohl Literaturangaben über Synthese und Elementarzelle tiner Reihe ternärer und quaternä-rer Selenogermanate vorhanden sind, wie BaGeSe3 [2], CcLiGeSee [3] sowie Cu2CdGeSe4 und Ag2ZnGeSe4 [4], fehlen bisher Strukturdaten für diese Verbindungsklasse weitgehend. Lediglich für die Verbindungen AgaGeSee [5], Cu2GeSe3 [6] und das aus wäßriger Lösung synthetisierte Selenogermanat Na4GeSe4 • 14 H2O [7] liegen vollständige Strukturbestimmungen vor.…”