The composite structure of mixed tau-(Ag, Cu)(x)V2O5 bronzes Evidence for T dependant guest-species ordering and mobility

Summary, in English

The complex structural behavior of tau-[AgCu](similar to 0.92)V4O10 has been elucidated by single crystal X-ray diffraction and thermal analysis. The tau-phase region is apparently composed of several distinct phases and this study identifies at least three: tau(1rt) tau(2rt) and tau(1t), tau(1rt) and tau(2rt) have slightly different compositions and crystal habits. Both phases transform to Tit at low temperature. The room temperature modification tau(1rt) crystallizes in an incommensurately modulated structure with monoclinic symmetry C2(0 beta 1/2) [equivalent to no 5.4, B2(01/2 gamma) in the Intnl. Tables for Crystallography, Volume C] and the cell parameters a=11.757(4) angstrom, b=3.6942(5) angstrom c = 9.463(2) beta=114.62(2)degrees and the q-vector (0 0.92 1/2), but it is more convenient to transform this to a setting with a non-standard centering X=(1/2 1/20 0; 0 0 1/2 1/2; 1/2 1/2 1/2 1/2;) and an axial q vector (00.92 0). The structure features a vanadate host lattice with Cu and Ag guests forming an incommensurate composite. The structural data indicates perfect Ag/Cu ordering. At low temperature this modification is replaced by a triclinic phase characterized by two independent q-vectors. The tau(2rt) phase is similar to the low temperature modification tau(lt) but the satellite reflections are generally more diffuse. (C) 2012 Elsevier Inc. All rights reserved.

• Author: Wilfred Hermes; Mickael Dolle; Patrick Rozier; Sven Lidin
• Department/s: Centre for Analysis and Synthesis
• Publishing year: 2013
• Language: English
• Pages: 84-89
• Publication/Series: Journal of Solid State Chemistry
• Volume: 199
• Links: http://dx.doi.org/10.1016/j.jssc.2012.11.029
• Document type: Journal article
• Publisher: Elsevier
• Topic: Chemical Sciences
• Keywords: Cu; Modulated composite; Ag bronze; Ionic transport
• Status: Published
• ISBN/ISSN/Other: ISSN: 0022-4596