| Budget Amount *help |
¥1,900,000 (Direct Cost: ¥1,900,000)
Fiscal Year 1986: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1985: ¥1,400,000 (Direct Cost: ¥1,400,000)
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| Research Abstract |
The objective of the project is to find out methods for determining migration properties of point defects in metal oxides through observations of defect aggregations during irradiation in a high voltage electron microscope. Results have been obtained on dislocation loop kinetics and migration energies of point defects in MgO, <Al_2> <O_3> and Mg <Al_2> <O_4> , and they are summerized as follows:
1. The volume density <C_L> and the diameter D of loops in MgO are shown for MgO as a function of the electron flux <phi> , irradiation time t and irradiation temperature T by <C_L> <proportion> <phi^(1/2)> <t^theta> /( <M_I> ) <^(1/2)> and D <proportion> <t^(1/3)> for T<900K and by D <phi^(1/2)> <M_U> for T>900K, where <M_I> and <M_U> are respectively the mobility of interstitials and vacancies. The experimental results on <C_L> and D give the migration energies of the siower interstitial and vacancy as 0.05 eV and 2.0 eV, respectively.
2. The dependence of <C_L> and D on <phi> and t for <Al_2> <O_3> containing holes is expressed by <C_L> <proportion> <phi^2> t/ <M_I> <Cu_O^2> and D <phi> t/ <Cu_O> , where <Cv_O> is the concentration of holes, yielding migration energy of interstitials as 0.76 eV.
3. No loop is detected in chemically polished Mg <Al_2> <O_4> irradiated by 1 MeV electrons at 100-1000K. Mg <Al_2> <O_4> irradiated by 6 keV <Ar^+> ions, on the other hand, shows tinny loops, which are 1/6<111> interstitial type in character and are not stable under 1 MeV electron irradiation. A study on the mechanism of the dislocation loop behavior for Mg <Al_2> <O_4> is under the progress.
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