ChemInform Abstract: Phase Relations in La₂O₂X—MX (M: Zn, Cd, Hg; X: S, Se) Systems. Structure of a New Cadmium Lanthanum Oxoselenide.

Abstract

Phase Relations in La 2 O 2 X-MX (M: Zn, Cd, Hg; X: S, Se) Systems. Structure of a New Cadmium Lanthanum Oxoselenide.-The phase relations in the title systems are studied at 1000 K. The sulfide and the selenide system of zinc as well as the sulfide system of cadmium are quasibinary and do not contain any novel phases. Moreover, the mercury systems are unstable. However, a novel phase of composition (LaO) 2 CdSe 2 , which crystallizes in the tetragonal system (space group P4 2 mc with Z = 2), is detected in the La 2 O 2 Se-CdSe system. -(BARANOV, I. YU.; DOLGIKH, V. A.; POPOVKIN, B. A.; Zh.

Infinitely Adaptive Transition Metal Oxychalcogenides: The Modulated Structures of Ce2O2MnSe2 and (Ce0.78La0.22)2O2MnSe2

“…The ZrCuSiAs-type layered structure is also found for the Cu + -containing oxychalcogenides LnOCuCh (Ln = Y, La–Nd; Ch = S, Se). − When Cu + ions in the Cu–Se layers of LnOCuSe are replaced by divalent metal cations M 2+ , layered structures of composition LnOM 0.5 Se (or Ln 2 O 2 MSe 2 ) may be formed in which only half of the tetrahedral sites in the selenide layer are occupied. Before this work, six different layered Ln 2 O 2 MSe 2 materials had been reported: Ce 2 O 2 MnSe 2 (CeOMn 0.5 Se), La 2 O 2 CdSe 2 , − Ce 2 O 2 FeSe 2 , La 2 O 2 FeSe 2 , La 2 O 2 ZnSe 2 , and Ce 2 O 2 ZnSe 2 . The difference between their structures is the ordering patterns of the M 2+ sites, as shown in Figure .…”