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Positron lifetime study in BaTiO 3 ceramics with different Ba/Ti ratios
Author(s) -
Tang C. Q.
Publication year - 1994
Publication title -
crystal research and technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.377
H-Index - 64
eISSN - 1521-4079
pISSN - 0232-1300
DOI - 10.1002/crat.2170290617
Subject(s) - stoichiometry , positron , materials science , analytical chemistry (journal) , ceramic , chemistry , metallurgy , nuclear physics , physics , electron , chromatography
The positron lifetime spectra in 0.25 at.% La‐doped BaTiO 3 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 τ 2 decreases and the intensity I 2 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 τ 2 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 < and Ti vacancies for Ba/Ti > 1.