Polymorphism of LiAg

• Published in: Solid state sciences Vol. 12; no. 2; pp. 274 - 280
• Main Authors: Pavlyuk, V.V., Dmytriv, G.S., Tarasiuk, I.I., Chumak, I.V., Pauly, H., Ehrenberg, H.
• Format: Journal Article
• Language: English
• Published: Issy-les-Moulineaux Elsevier Masson SAS 01.02.2010; Elsevier Masson
• Subjects: Condensed matter: structure, mechanical and thermal properties; Crystalline state (including molecular motions in solids); Crystallographic aspects of phase transformations; pressure effects; Exact sciences and technology; Intermetallic compound; Phase transition; Physics; Powder diffraction; Structure of solids and liquids; crystallography; Structure of specific crystalline solids; Intermetallic compound; Powder diffraction; Phase transition; Rietveld method; Cubic lattices; Space groups; Intermetallic compounds; Structure factors; Tetragonal lattices; Tetragonal crystals; Cesium chloride; Binary compounds; Diffraction pattern; Phase transitions; Direct method; Powder pattern; Structure modification; Polymorphism; Crystal structure
• ISSN: 1293-2558; 1873-3085
• DOI: 10.1016/j.solidstatesciences.2009.11.006

A phase transition from the cubic CsCl-type structure (Pm-3m space group) into a tetragonal UPb-type structure (I4 1/amd) is observed for the LiAg binary compound at ambient conditions. The crystal structure of the tetragonal modification of the LiAg binary compound was solved by direct methods in SHELXS on the base of structure factors which were extracted from a powder diffraction pattern and refined by SHELXL and the Rietveld method ( a = 3.9605(1), c = 8.2825(2) Å, Bragg R-factor = 4.81, Rf-factor = 4.87). Elevated temperatures and/or a small Li-excess versus the equimolar composition favour the cubic structure whereas ambient and lower temperatures and/or a small Li-deficiency stabilize the tetragonal structure. This reconstructive transition is reversible but proceeds slowly. [Display omitted]