INVESTIGATIONS OF RADIATION EFFECTS IN METAL OXIDES AND AZIDES BY ELECTRON SPIN RESONANCE. Progress Report, February 1, 1963-January 31, 1964
Radioinduced defects in single crystals of metal oxides and metal azides are being investigated by electron-spin resonance. The radiation is supplied by an electron accelerator, the Brookhaven Research Reactor, Co/sup 60/ gamma-ray sources, and ultraviolet lamps. The major objectives are the identification of radioinduced defects, a study of their growth and stability, and the correlation of these defects with changes in the properties of the irradiated solids. The ESR spectra of gamma-irradiated Al/sub 2/O/sub 3/ are attributed to F centers and to holes trapped at charge-deficient cation sites, Reactor-irradiated Al/sub 2/O/ sub 3/ has two prominent ESR spectra; one of these is attributed to (AlO)/sup 3/- molecules formed by replacement collisions, and the other remains unidentified but appears to be a superposition of many spectra. Reactor plus low-temperature gamma irradiation yields a spectrum attributed to interstitial 0/sup +/. Electron irradiation of Al/sub 2/O/sub 3/ is in progress. The new spectra are not identified, but it is established that the threshold energy for oxygen displacements by electron bombardment is below 1 Mev. A number of possible defects in Al/sub 2/O/sub 3/ are investigated theoretically. It is concluded from this investigation that interstitial 0/sup 0/ should have no ESR spectrum at 3-cm wavelength, that interstitial 0/sup +/ should have no optical spectrum, and that the defects at cation sites which trap holes are vacancies rather than impurities. In addition, a 7.4-ev optical band is associated with F centers, a 3.08-ev band with trapped holes, and a 2.00-ev band with interstitial 0/sup 0/. It is proposed that measurements be made with improved resolution, using K-band ESR and ENDOR techniques, Measurements on the growth, innealing, and threshold energy for production of electron-induced defects in Al/sub 2/O/sub 3/ will continue, and the identification of centers responsible for new ESR spectra will be attempted. Theoretical calculations will be refined and extended to more centers including those induced by electron irradiation. Some effort will be devoted to other materials besides Al/sub 2/O/sub 3/. (auth)
- Research Organization:
- Connecticut. Univ., Storrs
- DOE Contract Number:
- AT(30-1)-2047
- NSA Number:
- NSA-18-014543
- OSTI ID:
- 4076654
- Report Number(s):
- TID-20237
- Resource Relation:
- Other Information: Orig. Receipt Date: 31-DEC-64
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ACCELERATORS
ALUMINUM OXIDES
ANIONS
ANNEALING
BGRR
CATIONS
COBALT 60
COLLISIONS
DEFECTS
ELECTRON BEAMS
ELECTRON SPIN RESONANCE
ELECTRONS
ENERGY
EXPANSION
F CENTERS
FREQUENCY
GAMMA SOURCES
LATTICES
LIGHT
LOW TEMPERATURE
MEASURED VALUES
METALS
MOLECULES
MONOCRYSTALS
NITRIDES
NUMERICALS
OXIDES
OXYGEN
RADIATION EFFECTS
RESEARCH REACTORS
RESOLUTION
RESONANCE
SOLIDS
SPECTRA
SPIN
STABILITY
THRESHOLD ENERGY
TRAPS
ULTRAVIOLET RADIATION
VACANCIES
VARIATIONS