P-T phase diagram and gold valence state of the perovskite-type mixed-valence compounds Cs[sub 2]Au[sub 2]X[sub 6] (X = Cl, Br, and I) under high pressures
- Kyoto Univ. (Japan)
- Inst. for Molecular Science, Okazaki (Japan)
- National Lab. for High Energy Physics, Tsukuba (Japan)
We have elucidated the structural P-T phase diagram of Cs[sub 2]Au[sub 2]X[sub 6] (X = Cl, Br, and I) under high pressures and high temperatures for the first time. When the pressure is applied at room temperature, the Cs[sub 2]Au[sub 2]X[sub 6] (X = Cl, Br, and I) compounds undergo a tetragonal-to-tetragonal phase transition at 11, 9, and 5.5 GPa, respectively. This transition is regarded as a band Jahn-Teller transition driven by the Au[sup I,III] [yields] Au[sup II] transition. The cubic perovskite structure appears under high pressures and high temperatures for all three compounds. For Cs[sub 2]Au[sub 2]Br[sub 6] and Cs[sub 2]Au[sub 2]I[sub 6], the cubic phase could be obtained as a metastable state at room temperature and ambient pressure. The Au valence states in the second tetragonal phase and the cubic phase are considered to be Au[sup II]. 23 refs., 16 figs.
- OSTI ID:
- 6617940
- Journal Information:
- Journal of the American Chemical Society; (United States), Vol. 116:25; ISSN 0002-7863
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
CESIUM COMPOUNDS
PHASE TRANSFORMATIONS
X-RAY DIFFRACTION
GOLD COMPOUNDS
BROMIDES
CHLORIDES
HIGH PRESSURE
IODIDES
JAHN-TELLER EFFECT
PEROVSKITES
PHASE DIAGRAMS
VALENCE
ALKALI METAL COMPOUNDS
BROMINE COMPOUNDS
CHLORINE COMPOUNDS
COHERENT SCATTERING
DIAGRAMS
DIFFRACTION
HALIDES
HALOGEN COMPOUNDS
IODINE COMPOUNDS
MINERALS
SCATTERING
TRANSITION ELEMENT COMPOUNDS
400201* - Chemical & Physicochemical Properties
400102 - Chemical & Spectral Procedures