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Title: Superspace-group approach to the phase transition of Cu{sub 8}GeSe{sub 6}

Abstract

The high- and low-temperature forms, i.e., phase I (stable above 328 K) and phase II (stable below 328 K), of Cu{sub 8}GeSe{sub 6} have been investigated by the powder X-ray diffraction method. Cu{sub 8}GeSe{sub 6} II is hexagonal with A = 12.6438(2), C = 11.7570(1) {angstrom}, Z = 6, and P6{sub 3}cm, and its structure is considered to be a superstructure of the high-temperature form, Cu{sub 8}GeSe{sub 6} I (hexagonal, a = 7.3164(4) {approx_equal} A/{radical}3, c = 11.7679(7) {angstrom}, Z = 2, and P6{sub 3}mc). Rietveld analysis of Cu{sub 8}GeSe{sub 6} I (350 K) and II (290 K) has been performed using diffraction data measured by a high-resolution powder diffractometer and synchrotron X-ray radiation. For Cu{sub 8}GeSe{sub 6} II, a four-dimensional superspace group for commensurate modulation, P6{sub 3}mc (1/3 1/3 0), with basic cell constants a = 7.2999, c = 11.7570 {angstrom} has been successfully applied (R{sub wp} = 0.054). The superspace-group description allows uniform treatment of both forms, and the phase transition of Cu{sub 8}GeSe{sub 6} is explained in terms of the presence and absence of commensurate modulation waves.

Authors:
; ; ;  [1]; ;  [2]
  1. National Inst. for Research in Inorganic Materials, Namiki, Tsukuba (Japan)
  2. Univ. of Lausanne (Switzerland). Inst. of Crystallography
Publication Date:
OSTI Identifier:
696669
Resource Type:
Journal Article
Journal Name:
Journal of Solid State Chemistry
Additional Journal Information:
Journal Volume: 146; Journal Issue: 2; Other Information: PBD: Sep 1999
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; CRYSTAL STRUCTURE; PHASE STUDIES; COPPER SELENIDES; GERMANIUM SELENIDES; TEMPERATURE DEPENDENCE; X-RAY DIFFRACTION; LATTICE PARAMETERS; CALORIMETRY; EXPERIMENTAL DATA

Citation Formats

Onoda, Mitsuko, Ishii, Motohiko, Shibata, Kenji, Yamamoto, Akiji, Pattison, P., and Chapuis, G. Superspace-group approach to the phase transition of Cu{sub 8}GeSe{sub 6}. United States: N. p., 1999. Web. doi:10.1006/jssc.1999.8362.
Onoda, Mitsuko, Ishii, Motohiko, Shibata, Kenji, Yamamoto, Akiji, Pattison, P., & Chapuis, G. Superspace-group approach to the phase transition of Cu{sub 8}GeSe{sub 6}. United States. doi:10.1006/jssc.1999.8362.
Onoda, Mitsuko, Ishii, Motohiko, Shibata, Kenji, Yamamoto, Akiji, Pattison, P., and Chapuis, G. Wed . "Superspace-group approach to the phase transition of Cu{sub 8}GeSe{sub 6}". United States. doi:10.1006/jssc.1999.8362.
@article{osti_696669,
title = {Superspace-group approach to the phase transition of Cu{sub 8}GeSe{sub 6}},
author = {Onoda, Mitsuko and Ishii, Motohiko and Shibata, Kenji and Yamamoto, Akiji and Pattison, P. and Chapuis, G.},
abstractNote = {The high- and low-temperature forms, i.e., phase I (stable above 328 K) and phase II (stable below 328 K), of Cu{sub 8}GeSe{sub 6} have been investigated by the powder X-ray diffraction method. Cu{sub 8}GeSe{sub 6} II is hexagonal with A = 12.6438(2), C = 11.7570(1) {angstrom}, Z = 6, and P6{sub 3}cm, and its structure is considered to be a superstructure of the high-temperature form, Cu{sub 8}GeSe{sub 6} I (hexagonal, a = 7.3164(4) {approx_equal} A/{radical}3, c = 11.7679(7) {angstrom}, Z = 2, and P6{sub 3}mc). Rietveld analysis of Cu{sub 8}GeSe{sub 6} I (350 K) and II (290 K) has been performed using diffraction data measured by a high-resolution powder diffractometer and synchrotron X-ray radiation. For Cu{sub 8}GeSe{sub 6} II, a four-dimensional superspace group for commensurate modulation, P6{sub 3}mc (1/3 1/3 0), with basic cell constants a = 7.2999, c = 11.7570 {angstrom} has been successfully applied (R{sub wp} = 0.054). The superspace-group description allows uniform treatment of both forms, and the phase transition of Cu{sub 8}GeSe{sub 6} is explained in terms of the presence and absence of commensurate modulation waves.},
doi = {10.1006/jssc.1999.8362},
journal = {Journal of Solid State Chemistry},
number = 2,
volume = 146,
place = {United States},
year = {1999},
month = {9}
}