中文摘要：

用符合正电子湮没辐射Doppler展宽技术研究了La2／3Ca1／3Mn1-xFexO3陶瓷的缺陷和3d电子行为。结果表明：对x≤0．33的样品，随着样品中Fe含量的增加，3d电子数量增加，样品的商谱谱峰升高；对x〉0．50的样品，随着样品中Fe含量的增加，样品中有新相生成，体系缺陷增加，样品的商谱谱峰降低。测试了La2／3Ca1／3Mn1-xFexO3多晶陶瓷的磁电阻性能，讨论了微观缺陷和3d电子对La2／3Ca1／3Mn1-xFexO3多晶陶瓷磁电阻性能的影响。

英文摘要：

The defects and 3d electrons in La2/3Ca1/3Mn1-xFexO3 ceramics were studied by coincidence Doppler- broadening spectra of positron annihilation radiation. The results show that for samples with x≤0.33, the peaks of the ratio curves of Doppler broadening spectra of the ceramic samples increase with the Fe content due to the increasing in the number of 3d electrons. For samples with x〉0. 50, with increasing of Fe content, the peaks of the ratio curves of the samples decrease due to the formation of new phases and giving rise to the increase of the defect concentration. The magneto-resistance property measurements were performed in theLa2/3Ca1/3Mn1-xFexO3 ceramics and the effects of defects and 3d electrons on magneto-resistance properties of La2/3Ca1/3Mn1-xFexO3 ceramics were discussed.