摘要
采用固相反应法制备了La0.67Ca0.33Mn0.9A0.1O3(其中A为Cr、Co、Fe、Al、Cu)系列Mn位替代的氧化物样品;利用正电子湮没对该系列样品的结构缺陷进行了分析,结果表明:τ1的变化范围不大,表明样品主要受大尺寸点缺陷的影响,τ2的变化比较明显,说明样品内存在一定数量的空洞及微空洞等缺陷.类比合金中正电子长寿命与缺陷簇之间的关系,估算了元素替代后样品的缺陷半径大小,可能大的空位团簇、位错和晶界在样品中起着重要作用.按Cr、Co、Fe、Al、Cu的掺杂顺序,平均寿命τavg逐渐增加,而电子密度ne则逐渐减小.说明元素掺杂引起锰离子局域环境的改变,样品中的铁磁与反铁磁作用的相互竞争及样品内部电子局域化所形成的极化行为等因素的影响,导致了正电子寿命各参数的变化.
Samples Laνo.67Caνo.33Mnl_xAνxOν3（A= Cr, Fe, Co, Cu, AI; x=0.1） had been prepared by the standard solid-state reaction. The positron annihilation technology （PAT） was used to detect the defect and electronic structure of the samples. The results showed that the variety of rνl was small comparing with rν2, which attributes to the rich number of large defect. Based on the relation between rν2 and the dimension of defect cluster, the radius of defeet was calculated. The rνavg gradually augmented in order of Cr, Co, Fe, A1, Cu, whereas nνe is reverse. The Mn ion local environment change, the mutual competition functions between ferromagnetic and anti-ferromagnetic, the sample interior electron polarized behavior all contribute to variety of the positron life parameter. Therefore, appropriate doping is helpful for electromagnetism property.
出处
《江西师范大学学报（自然科学版）》
CAS
北大核心
2011年第5期494-497,共4页
Journal of Jiangxi Normal University(Natural Science Edition)
基金
贵州省教育厅自然科学研究项目(20090099)
黔西南州科技局科技计划(2010-43)资助项目
关键词
正电子湮没
掺杂
锰氧化物
positron annihilation
doping
manganese oxide
