F sup + center as a paramagnetic probe in the EPR investigation of barium hexaaluminate phases I and II and barium-lanthanum hexaaluminate ceramics

Journal Article · Fri Dec 01 00:00:00 EST 1989 · Journal of Solid State Chemistry; (USA)

DOI:https://doi.org/10.1016/0022-4596(89)90184-9· OSTI ID:6715913

Gbehi, T; Gourier, D; Thery, J; Vivien, D ^[1]

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1. Laboratoire de Chimie Appliquee de l'etat solide, Paris (France)

An X-ray-induced F{sup +} center is used as a paramagnetic probe to study sintered powders of barium hexaaluminates phases I and II (referred to as Ba({Phi}{sub I}) and Ba({Phi}{sub II})) and mixed barium-lanthanum hexaaluminate (referred to as BLA). This F{sup +} center was previously shown to exist only in {beta}-alumina-type mirror planes containing interstitial oxygen ions as charge-compensating defects, so that its study yields information about the local structure of this type of mirror plane. By comparison of the EPR spectra of Ba({Phi}{sub I}) and Ba({Phi}{sub II}) it is shown that the latter contains only one type of F{sup +} center with a reduced hf interaction. This indicates that there is only one type of mirror plane containing interstitial oxygen in Ba({Phi}{sub II}) and that the separation between spinel blocks is larger in Ba({Phi}{sub II}) than in Ba({Phi}{sub I}). This result agrees with models proposed by other authors for barium-lead hexaaluminate and barium hexagallate. Investigation of the F{sup +} center in mixed barium-lanthanum hexaaluminate ceramics clearly supports the hypothesis of segregation of Ba{sup 2+} ions in {beta}-alumina-type mirror planes. It is also shown that the structure of these planes is very similar to that of Ba({Phi}{sub II}) defect planes.

• OSTI ID: 6715913
• Journal Information: Journal of Solid State Chemistry; (USA), Vol. 83:2; ISSN 0022-4596
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
CERAMICS
PHASE STUDIES
ALUMINATES
BARIUM
DATA ANALYSIS
EPR SPECTROMETERS
EXPERIMENTAL DATA
FLUORINE IONS
LANTHANUM
MEASURING INSTRUMENTS
MEASURING METHODS
ALKALINE EARTH METALS
ALUMINIUM COMPOUNDS
CHARGED PARTICLES
DATA
ELEMENTS
INFORMATION
IONS
METALS
NUMERICAL DATA
OXYGEN COMPOUNDS
RARE EARTHS
SPECTROMETERS
360202* - Ceramics
Cermets
& Refractories- Structure & Phase Studies