Anionogenic mixed valency in KxBa1-xO2-δ.
Inorg Chem
; 53(1): 496-502, 2014 Jan 06.
Article
en En
| MEDLINE
| ID: mdl-24328297
ABSTRACT
We have synthesized members of an isostructural solid solution series KxBa1-xO2-δ (x < 0.41, δ < 0.11) containing mixed-valent dioxygen anions. Synthesis in liquid ammonia solution allows a continuous range of compounds to be prepared. X-ray and neutron diffraction show that KxBa1-xO2-δ adopts the tetragonal rocksalt-derived structure of the end members KO2 and BaO2, without any structural phase transition down to 5 K, the lowest temperature studied here. We identify four oxygen-oxygen stretching modes above 750 cm(-1) in the measured Raman spectra, unlike the spectra of KO2 and BaO2 which both contain just a single mode. We use density functional theory calculations to show that the stretching modes in KxBa1-xO2-δ arise from in-phase and anti-phase coupling of the stretching of nearest-neighbor oxygen dimers when the valence state of the dimers lies between -1 and -2 because of mixed cation coordination. This coupling is a direct signature of a novel type of anionogenic mixed valency.
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1
Colección:
01-internacional
Banco de datos:
MEDLINE
Idioma:
En
Revista:
Inorg Chem
Año:
2014
Tipo del documento:
Article
País de afiliación:
Países Bajos