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Averback, R.S. Van Sambeek, Andrew I. 2015-09-25T20:53:28Z 2015-09-25T20:53:28Z 10000-01-01 1997 1997 Radiation enhanced diffusion of O$\sp{18}$, Ca and Zn buried tracer layers in MBE grown MgO was measured following irradiation with either 2.0 MeV Kr or 1.0 MeV Ne, He or H from 30 to 1500$\sp\circ$C. This represents the first reported RED measurements on an oxide system. Ion beam mixing at 30$\sp\circ$C on both sublattices was approximately 1.0 to 5.0 A$\sp5$/ev indicating the temperature independent mixing (ballistic mixing) is produced only by direct recoil and cascade events and that thermal spikes are not significant. D$\sb{\rm red}$ was proportional to the square root of the irradiation flux with an activation enthalpy of 1.2 eV for diffusion on the anion sublattice from 1350 to 1500$\sp\circ$C. The flux dependence is characteristic of kinetics in the recombination limited regime; accordingly, the measured activation enthalpy of 1.2 eV is identified as one-half the migration enthalpy of the anion vacancy. This assignment agrees with the predicted anion vacancy migration enthalpy of 2.1 to 2.4 eV. Between 1150$\sp\circ$C and 1350$\sp\circ$C an apparent activation enthalpy of 4.1 eV was measured. This enthalpy was attributed to vacancy clustering reactions. Measurements on the cation sublattice were conducted at temperatures below 900$\sp\circ$C. At higher temperatures excessive thermal diffusion from extrinsic vacancies stemming from trivalent impurities prevented measurements of RED. Made available in DSpace on 2015-09-25T20:53:28Z (GMT). No. of bitstreams: 2 license.txt: 4848 bytes, checksum: 96035ab3f5e1c23cc7138a224ce498bd (MD5) 9737278.pdf: 4982265 bytes, checksum: b390879d8ef98e3c930921348d463bcb (MD5) Previous issue date: 1997 Embargo set by: Seth Robbins for item 84163 Lift date: Forever Reason: Restricted to the U of I community idenfinitely during batch ingest of legacy ETDs Restricted to the U of I community idenfinitely during batch ingest of legacy ETDs U of I Only 120 p. Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1997. http://hdl.handle.net/2142/82882 (MiAaPQ)AAI9737278 eng Physics, Radiation Radiation-Enhanced Diffusion and Defect Production During Ion Irradiation of MgO and Al(2)O(3) text Materials Science and Engineering Materials Science and Engineering University of Illinois at Urbana-Champaign Dissertation Ph.D.