Optical absorption and electron paramagnetic resonance studies of chemically reduced congruent lithium niobate
| Autor: | Gary G. DeLeo, F. J. Feigl, David A. Dutt |
|---|---|
| Rok vydání: | 1990 |
| Předmět: |
Bipolaron
genetic structures Lithium niobate Analytical chemistry General Chemistry Electron Condensed Matter Physics Polaron law.invention chemistry.chemical_compound Nuclear magnetic resonance chemistry law Electrical resistivity and conductivity Chemical reduction General Materials Science Electron paramagnetic resonance Single crystal |
| Zdroj: | Journal of Physics and Chemistry of Solids. 51:407-415 |
| ISSN: | 0022-3697 |
| DOI: | 10.1016/0022-3697(90)90175-f |
| Popis: | An optical absorption and electron paramagnetic resonance (EPR) study has been performed on a series of chemically reduced congruent lithium niobate (LiNbO3) samples. Chemical reduction enhances the high-temperature electrical conductivity and darkens an otherwise optically clear crystal. The resulting optical spectra show a sharp threshold absorption above 3.8 eV and the growth of a broad-band absorption featuring a peak at 2.4 eV. The strength of the broad-band absorption is directly correlated with the carriers responsible for the enhanced high-temperature electrical conductivity. Optical illumination (bleaching) at 87 K shifts the optical absorption peak from 2.4 to 1.6 eV and produces an enhanced Nb4+ EPR signal. A quantitative analysis shows that the 1.6 eV optical absorption and the Nb EPR signal are both consistent with single electrons trapped on Nb atoms. The experimental results are discussed in terms of oxygen vacancy and bipolaron models. |
| Databáze: | OpenAIRE |
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