Theoretical Calculations of Positron Lifetimes for Metal Oxides
Theoretical Calculations of Positron Lifetimes for Metal Oxides
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DOI：
10.2320/matertrans.45.1964
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发表时间：
2004-07
影响因子：
1.2
通讯作者：
M. Mizuno;H. Araki;Y. Shirai
中科院分区：
文献类型：
--
作者：
M. Mizuno;H. Araki;Y. Shirai
我们最近对金属氧化物的正电子寿命的测量表明，金属氧化物的体态正电子寿命比以前报道的值短。我们利用第一性原理电子结构计算方法对氧化镁和氧化锌的体态和空位态的正电子寿命进行了理论计算，并讨论了正电子寿命计算对绝缘体的有效性。通过将计算的正电子寿命与实验值进行比较，发现半导体模型能很好地再现实验正电子寿命。先前报道的较长的正电子寿命可以认为不仅来自于体积，而且来自于杂质引起的空位。在阳离子空位的情况下，基于半导体模型计算的正电子寿命比实验值短，这表明正电子在阳离子空位周围发生向内弛豫。
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.