Study of protons in acceptor-doped KTaO sub 3 crystals by IR and EPR techniques

Journal Article · Fri Dec 01 04:00:00 EST 1989 · Journal of Solid State Chemistry; (USA)

DOI:https://doi.org/10.1016/0022-4596(89)90171-0· OSTI ID:6715303

Fu, S Q; Lee, W K; Nowick, A S ^[1]; Boatner, L A; Abraham, M M ^[2]

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1. Columbia Univ., New York, NY (USA)
2. Oak Ridge National Laboratory, TN (USA)

In order to understand the manner of incorporation of protons into perovskite structure oxides, KTaO{sub 3} crystals containing acceptor dopants Co{sup 2+}, Mn{sup 2+}, Cu{sup 2+}, and Fe{sup 3+} were investigated following thermal treatments in various partial pressures of O{sub 2} and H{sub 2}O. IR measurements were used to monitor the proton content through the OH{sup {minus}} absorption bands, while quantitative EPR measurements wee used to determine the changes in the local environment of the dopant ion. It is shown that the introduction of protons during high-temperature treatments in H{sub 2}O is accompanied by the replacement of the oxygen-ion vacancies (V{sub o}) that initially compensated the acceptor dopants by O{sup 2{minus}} ions. In the case of the M{sup 2+} dopants, the dopant-vacancy association free energy is sufficiently strong to retain the M-V{sub o} pairs even during high-temperature (900{degree}C) treatments; thus, only <100> axial EPR spectra due to such pairs are observed. For Fe{sup 3+} dopants, however, virtually all of the V{sub o} can be replaced by O{sup 2{minus}}, leaving the Fe{sup 3+} ion in a cubic environment. The results also show evidence for valence changes of the Co, Mn, and Cu dopants when treatments change from oxidizing to reducing atmospheres.

• DOE Contract Number: FG02-88ER45341; AC05-84OR21400
• OSTI ID: 6715303
• Journal Information: Journal of Solid State Chemistry; (USA), Journal Name: Journal of Solid State Chemistry; (USA) Vol. 83:2; ISSN JSSCB; ISSN 0022-4596
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360204* -- Ceramics
Cermets
&amp; Refractories-- Physical Properties
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400102 -- Chemical &amp; Spectral Procedures
CHALCOGENIDES
CHARGED PARTICLES
CHARGED-PARTICLE TRANSPORT
COBALT IONS
COPPER IONS
DATA
DATA ANALYSIS
ELECTRON PROBES
EXPERIMENTAL DATA
INFORMATION
INFRARED SPECTRA
IONS
IRON IONS
MANGANESE IONS
MEASURING INSTRUMENTS
MEASURING METHODS
NUMERICAL DATA
OXIDES
OXYGEN COMPOUNDS
PEROVSKITES
PROBES
PROTON TRANSPORT
RADIATION TRANSPORT
REFRACTORY METAL COMPOUNDS
SPECTRA
TANTALUM COMPOUNDS
TANTALUM OXIDES
TRANSITION ELEMENT COMPOUNDS
VERY HIGH TEMPERATURE