施主掺杂BaTiO_3陶瓷的正电子湮没和顺磁共振研究

本文用正电子湮没和电子顺磁共振相结合的方法对施主掺杂BaTiO_3陶瓷的缺陷进行了研究。正电子湮没寿命测量说明与Ba/Ti=1的样品相比Ba过量或Ti过量都会引起材料中的空位增加。顺磁共振图谱表明,g=1.997峰的强度在铁电相变为顺电相后,强度有很大的增长(约20倍)。该峰强度随Ba/Ti的变化与正电子捕获率随Ba/Ti的变化相同。因此该峰是由阳离子空位(V_(Ba)和V_(Ti))引起的。它实质上是由O~-产生的,随施主掺量的增加g=1.997峰急剧增强,这很可能是由于施主增加引起V_(Ti)大量生成的缘故。

A Study of Doner Doped BaTiO_3 Ceramics by Positron Annihilation Technique and Electron Paramagnetic Resonance

The defects in doner doped BaTiO_3 ceramics were investigated by positron annihilation technique and paramagnetic resonance. The positron life time measurement indicated that compared with the sample with Ba/Ti=1,the defects in samples with Ba/Ti>1 or Ba/Ti<1 increased. The electron paramagnetic resonance showed that the intensity of signal with g=1. 997 augmented when the material underwent phase trasition from tetragonal to cubic(about 20 times). The intensity of that signal changed with Ba/Ti with the same law as that of positron capture coefficient. So the signal is correspondedto cation vacancies (V_(Ti) and V_(Ba)). It is caused by O~- in fact. The intensity of the signal with g=1. 997 increased tremedously with the increase of doner concentration. This may be explain by the reason that the doner in high concentration can cause the production of V_(Ti).