Electronic Properties of Oxide Insulators.
Final scientific rept. 16 Mar 69-15 Apr 71,
MINNESOTA UNIV MINNEAPOLIS SCHOOL OF CHEMISTRY
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Studies of the point defects in the alkaline earth oxides MgO, CaO, and SrO centered upon the trapped-electron of F-type centers, the trapped-hole or V1-type centers and the various valence states of substitutional impurities. Attempts have been made to correlate numerous other electronic properties - optical absorption, luminescence behavior, charge-release, phenomena, and the Hall coefficient with electron spin data. Largely, the behavior has been in accord with prediction, but with some surprises for example, the F center in MgO was observed to give a photo-induced Hall effect appropriate to holes as the majority carrier, whereas for the CaO and SrO one finds electrons, as expected. This is attributed to the very-low lying ground state of the F center in MgO, i.e., the level lies in the vicinity of the valence band. Two substitutional defects recently studied are the Fe3 ion and the Ti3 ion in MgO, both with an associated cation vacancy in the next-nearest neighbor cation position. These represent almost ideally simple examples of d1 andor d5 ions in octahedral-plus-tetragonal symmetry. Recent theoretical studies have been made of the hole trapped adjacent to a positive ion cavancy in order to determine the extent to which the localized model is applicable. Present results are not conclusive. Author
- Solid State Physics