巨磁阻材料Sr1.9Gd0.1FeMoO6光掺杂的正电子湮没研究

Study on Positron Lifetime Spectroscopy of Optical Doping in the Double Perovskite Oxide Sr_(1.9)Gd_(0.1)FeMoO_6

采用固相反应法制备Sr1.9Gd0.1FeMoO6样品,通过X射线衍射检验其为单相.在光照10、20、30、40 min后分别做了正电子湮没实验.研究了正电子寿命与光掺杂量之间的变化关系,分析了光掺杂对样品电子结构的影响.结果表明:正电子寿命参数对光掺杂量十分敏感,1τ、2τ随光照时间具有相同的变化趋势;在光照时间t>20 m in时,平均电子浓度随光照时间有明显的变化;持续的光掺杂使样品缺陷的平均尺寸相对减小,可能由微空洞、多空穴向双空穴或单空穴转变,使电子结构趋于有序化.

Polycrystalline Sr1.9Gd0.1FeMoO6 sample was prepared by standard solid-state reaction. The XRD pattern indicates that the sample was single phase without detectable impurity. The effect of optical doping on electronic structure of Sr1.9Gd0.1FeMoO6 was investigated with the illumination time 10 , 20, 30 and 40 min. The positron annihilation lifetime parameters1τ、2τ are sensitive to optical doping, The average electron density n, increases pronouncedly for t〉20 min. Detailed analysis suggests that the type and the number of structural defects change with different doping levels.