Positron lifetime study in BaTiO3 ceramics with different Ba/Ti ratios
✍ Scribed by Prof. C. Q. Tang
- Publisher
- John Wiley and Sons
- Year
- 1994
- Tongue
- English
- Weight
- 228 KB
- Volume
- 29
- Category
- Article
- ISSN
- 0232-1300
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✦ Synopsis
The positron lifetime spectra in 0.25 at.% La-doped BaTiO, with different Ba/Ti ratios have been measured at room temperature. It was found from the experiments that with deviating from exact stoichiometry the positron lifetime z2 decreases and the intensity I , increases for Ba/Ti ratio smaller than stoichiometric and they have more significantly similar changes for Ba/Ti ratio larger than stoichiometric. The non-monotonic dependence of positron lifetime parameters on Ba/Ti ratio is regarded as that the r2 component is contributed together by positrons annihilating at the grain boundaries and Ba vacancies and/or Ti vacancies, and small deviations from exact stoichiometry would be expected to increase the concentration of defects such as Ba vacancies for Ba/Ti < 1 and Ti vacancies for Ba/Ti > 1.