用正电子湮没技术研究掺杂粉末β-C_2S的缺陷

Study of defects in doped β-C2S powder samples by positron annihilation

对硅酸二钙(Ca_2SiO_4简写为C_2S)掺杂,可以影响它的微观结构、多晶转变、烧成速度等。硅酸二钙是干燥的坚硬粉末,不易压制成型。我们采用垂直放置闪烁探头的测量方法,测量了β-C_2S粉末的正电子湮没寿命谱。结果表明,中间寿命τ_2(约470ps)组分,相应于正电子在钙空位处束缚态湮没。I_2随Na掺量增大而减小,随P掺量增加而增大,表明Na进入Ca位置并产生阴离子空位,P^(5+)进入Si位置并产生Ca^(2+)空位。

Adding impurities toβ-C2S can affect its microstructure, polycrystalline transfer and rate of firing reaction. Being hard dry powder. β-C2S can not be compressed into pieces, so a vertical experimental arrangement is used. The lifetime spectrum of positrons in β-C2S powder samples added with Na2O and P2O5 is studied. The results show that the component with intermediate lifetime τ2 (about 470 pS) represents the capture of positrons in Ca2+ vacancies; the intensity I2 of τ2 decteases with increasing of Na+ and increases with increasing of P5+. The results also show that Na+ replaces Ca2+ and creates anion vacancies, but P5+ creates cation vacancies.