多晶钠离子导体Na_5Y_(1-x)Cr_xSi_4O_(12)的正电子湮没一维角关联辐射研究

The Study of Positron Annihilation One Dimension Angular-Correlation Radiation on Polycrystal Na^+ Ionic Conductor Na_5Y_(1-x)Cr_xSi_4O_(l2)

本文用正电子湮没辐射一维角关联实验装置,测量了多晶钠离子导体Na_5Y_1—xCr_xSi_4O_(12)(简称NYCS)系列各组分的正电子湮没辐射的一维角关联曲线,对测得的电子动量分布曲线归一化后,计算了线形参数,从H、W和S参数反映出NYCS系列样品中Na^+离子空位浓度的变化。测试结果表明,Cr_2O_3的含量不同,对多晶NYCS样品的一维角关联曲线的H、W和S参数均有很大影响,随Cr_2O_3的加入,H和S参数提高,W参数下降,当x=0.05时,两者均达到极值;继续加入Cr_2O_3,则H和S参数下降,W参数提高。这些结果说明,加入Cr_2O_3后,电导率的变化和Na^+离子空位浓度的变化密切相关,Na^+离子空位浓度增加,电导率提高,反之则降低。

With Positron annihilation radiation one dimension angular-correlation device, it ismeasured that positron annihilation radiation one dimension angular-correlation curves of polycrystalsodium ionic conductor Na_5Y_(1-x).Cr_xSi_4O_(12) (NYCS) systems. Since electron momentum distributioncurves are normalized, line shape parameters are calculated. The H, W and S parameters show thechange of Na^+ ion vacancy content in NYCS series samples. The results show that H,W and S pa-rameters of one dimension angular-correlation curves of those samples vary greatly with Cr_2O_3 con-tent. With Cr_2O_3 content increasing, H and S parameters increase, but W decreases, and get to ex-tremes at X=0. 05, than increasing Cr_2O_3 content again, H and S decrease, W increases. This showsthat, in addition to Cr_2O_3, the conductivity has intimate relation with the content of Na^+ vacancies.