Radiation damage in MgAl/sub 2/O/sub 4/

Journal Article · Sat Mar 15 04:00:00 EST 1980 · Phys. Rev., B: Condens. Matter; (United States)

DOI:https://doi.org/10.1103/PhysRevB.21.2578· OSTI ID:5471248

Summers, G P; White, G S; Lee, K H; Crawford, Jr, J H

Exposure of single crystals of MgAl/sub 2/O/sub 4/ to fast neutrons and to Van de Graaff electrons with energies in excess of 0.35 MeV introduces an optical-absorption band at 5.3 eV with a 1-eV half-width. This band can be partially bleached at temperatures as low as 40 K and a shoulder at 4.75 eV develops concurrently. This bleaching treatment also partially destroys a previously reported V-type absorption centered at 3.2 eV. Subsequent exposure to ionizing radiation destroys the 4.75-eV band and restores both the 5.3- and 3.2-eV bands to their original intensities. Since this behavior is analogous to the interconversion of F to F/sup +/ centers in Al/sub 2/O/sub 3/, it is concluded that the 5.3-eV band is the principal optical transition of the F center (two electrons trapped at an oxide-ion vacancy) and the 4.75-eV band is attributed to absorption by the F/sup +/ center (one electron trapped at an oxide-ion vacancy). In electron-irradiated crystals the 5.3-eV absorption begins to anneal near 110 /sup 0/C and is about 90% destroyed upon isochronal annealing (10-min pulses) up to 355 /sup 0/C. Neutron-irradiated crystals behave similarly. Measurement of the threshold energy for damage by electrons at 77 K yields a displacement energy for the creation of O/sup 2 -/ interstitial-vacancy pairs of 59 eV. The defect yield drops off substantially with increasing temperature, and at room temperature the apparent O/sup 2 -/ displacement energy is 130 eV. Possible reasons for this strong temperature effect are discussed.

• Research Organization: Department of Physics, Oklahoma State University, Stillwater, Oklahoma 74074
• OSTI ID: 5471248
• Journal Information: Phys. Rev., B: Condens. Matter; (United States), Journal Name: Phys. Rev., B: Condens. Matter; (United States) Vol. 21:6; ISSN PRBMD
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360605* -- Materials-- Radiation Effects
ALKALINE EARTH METAL COMPOUNDS
ALUMINIUM COMPOUNDS
ALUMINIUM OXIDES
CHALCOGENIDES
COHERENT SCATTERING
COLLISIONS
CRYSTAL DEFECTS
CRYSTAL STRUCTURE
DIFFRACTION
ELECTRON COLLISIONS
INTERSTITIALS
MAGNESIUM COMPOUNDS
MAGNESIUM OXIDES
MEDIUM TEMPERATURE
NEUTRON DIFFRACTION
OPTICAL PROPERTIES
OXIDES
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
PHYSICAL RADIATION EFFECTS
POINT DEFECTS
RADIATION EFFECTS
SCATTERING
TEMPERATURE DEPENDENCE
VACANCIES