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Home  >  Journal list  >  MATERIALS TRANSACTIONS  >  Vol.45  No.7 (2004)  >  pp.1964-1967

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Theoretical Calculations of Positron Lifetimes for Metal Oxides

Masataka Mizuno1), Hideki Araki1) and Yasuharu Shirai1)
1) Science and Technology Center for Atoms, Molecules and Ions Control, Graduate School of Engineering, Osaka University

Our recent positron lifetime measurements for metal oxides suggest that positron lifetimes of bulk state in metal oxides are shorter than previously reported values. We have performed theoretical calculations of positron lifetimes for bulk and vacancy states in MgO and ZnO using first-principles electronic structure calculations and discuss the validity of positron lifetime calculations for insulators. By comparing the calculated positron lifetimes to the experimental values, it was found that the semiconductor model well reproduces the experimental positron lifetime. The longer positron lifetime previously reported can be considered to arise from not only the bulk but also from the vacancy induced by impurities. In the case of cation vacancy, the calculated positron lifetime based on semiconductor model is shorter than the experimental value, which suggests that the inward relaxation occurs around the cation vacancy trapping the positron.

positron annihilation, MgO, ZnO, vacancy, electronic structure

Received: January 23, 2004
Accepted: March 22, 2004 , Published online: June 24, 2005
Copyright (c) 2005 The Japan Institute of Metals



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