Optical spectra of MgAl/sub 2/O/sub 4/ crystals exposed to ionizing radiation
Exposure of MgAl/sub 2/O/sub 4/ crystals to /sup 137/Cs ..gamma.. rays produces a broad absorption complex centered near 3 eV and at the same time destroys absorption at 4.8 and 6.4 eV which is attributed to charge transfer transitions on octahedral Fe/sup 3 +/ impurity ions. Hence it is concluded that the 3 eV absorption is associated with transitions of holes trapped at sites deficient in positive charge and that electrons captured by Fe/sup 3 +/ ions decrease their absorption bands. Thermal and optical bleaching of the 3 eV absorption complex in crystals with differing Fe/sup 3 +/ concentration reveals that this complex is composed of absorption bands located at 2.8, 3.1, 3.6 and possibly at 3.9 eV. Analysis of the intense, persistent after glow and conductivity after ..gamma..-ray exposure and thermally stimulated conductivity discloses a very high concentration of shallow electron traps with a prominent set of these traps having a thermal depth of approx. 0.9 eV. It is proposed that anti-structure disorder, e.g., Al/sup 3 +/ ions on tetrahedral sites, is responsible for a substantial portion of these electron traps.
- Research Organization:
- North Carolina Univ., Chapel Hill (USA). Dept. of Physics and Astronomy
- DOE Contract Number:
- AS05-78ER05866
- OSTI ID:
- 6613217
- Report Number(s):
- ORO-5866-12; TRN: 81-004789
- Country of Publication:
- United States
- Language:
- English
Similar Records
Radiation damage in MgAl/sub 2/O/sub 4/
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/]
Related Subjects
ALUMINIUM OXIDES
ELECTRIC CONDUCTIVITY
PHYSICAL RADIATION EFFECTS
MAGNESIUM OXIDES
COLOR CENTERS
CRYSTAL LATTICES
GAMMA RADIATION
IMPURITIES
MONOCRYSTALS
THERMOLUMINESCENCE
ALKALINE EARTH METAL COMPOUNDS
ALUMINIUM COMPOUNDS
CHALCOGENIDES
CRYSTAL DEFECTS
CRYSTAL STRUCTURE
CRYSTALS
ELECTRICAL PROPERTIES
ELECTROMAGNETIC RADIATION
IONIZING RADIATIONS
LUMINESCENCE
MAGNESIUM COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
POINT DEFECTS
RADIATION EFFECTS
RADIATIONS
VACANCIES
360605* - Materials- Radiation Effects