Electronic structure of defects in oxides. Final report, December 1, 1979-November 30, 1980. [. cap alpha. -Al/sub 2/O/sub 3/; MgAl/sub 2/O/sub 4/]
Details of the electronic structure of F-type centers in the series of oxides SrO, CaO, ..cap alpha..-Al/sub 2/O/sub 3/ and MgAl/sub 2/O/sub 4/ have been determined using measurements of photoconductivity, luminescence, and fluorescence lifetimes. Measurements were made over the spectral range 2 to 6.5 eV and over the temperature range 4 to 350/sup 0/K. The centers were introduced into SrO by electron, on proton or neutron bombardment, into CaO and ..cap alpha..-Al/sub 2/O/sub 3/ by electron a neutron bombardment or thermochemical coloration, and into MgAl/sub 2/O/sub 4/ by particle bombardment. In some cases, notably CaO and ..cap alpha..-Al/sub 2/O/sub 3/, the photoconductivity behaves differently depending on the method used to introduce the centers. In particular, neutron irradiated and some thermochemically colored samples of sapphire contain an effective electron trap with an optical transition energy of approx. 5.0 eV and a thermal excitation energy of 0.72 eV as determined by measurements of photoconductivity, thermoluminescence and phosphorescence. This trap appears to be structural defect consisting of an aggragate of anion vacancies.
- Research Organization:
- Oklahoma State Univ., Stillwater (USA)
- DOE Contract Number:
- AS05-76ER04837
- OSTI ID:
- 7039102
- Report Number(s):
- DOE/ER/04837-7; TRN: 81-001012
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ALUMINIUM OXIDES
RADIATION EFFECTS
CALCIUM OXIDES
MAGNESIUM OXIDES
STRONTIUM OXIDES
ANIONS
F CENTERS
PHOSPHORESCENCE
PHOTOCONDUCTIVITY
THERMOLUMINESCENCE
VACANCIES
ALKALINE EARTH METAL COMPOUNDS
ALUMINIUM COMPOUNDS
CALCIUM COMPOUNDS
CHALCOGENIDES
CHARGED PARTICLES
COLOR CENTERS
CRYSTAL DEFECTS
CRYSTAL STRUCTURE
ELECTRIC CONDUCTIVITY
ELECTRICAL PROPERTIES
IONS
LUMINESCENCE
MAGNESIUM COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
POINT DEFECTS
STRONTIUM COMPOUNDS
360206* - Ceramics
Cermets
& Refractories- Radiation Effects