高活性β-C_2S的正电子湮没研究

POSITRON ANNIHILATION STUDY IN VERY ACTIVE β-C_2S

用正电子湮没技术(PAT)研究了不同热处理温度下合成的高活性β-C_2S的正电子湮没寿命谱。分析了高活性β-C_2S中对正电子捕获态寿命产生影响的主要因素,并按照正电子捕获理论,从实验所得寿命谱参数对高活性β-C_2S的结构缺陷特征进行了讨论。结果表明,寿命谱中的τ_2成分主要来自晶粒边界和高活性β-C_2S内部本身的结构缺陷。τ_2的强度I_2随热处理温度的提高而减小,说明温度升高,晶界和结构缺陷均减少。实验表明,正电子湮没技术亦可用于一些超细多晶材料。

The lifetime spectra of positron in very active β-C_2S synthesised at different temperatures were studied by using positron annihilation teahnique. The factors affecting on the positron trapping state lifetime in very active β-C_2S were analysed. According to the positron trapping theory, the structure characteristics of very active β-C_2S is discussed based on the lifetime spectrum parameters obtained from experiments. The results showed that τ_2 in lifetime spectrum comes mainly from both grain bounderies and structure defects in very active β-C_2S crystal itself. The intensity I_2 of τ_2 decreased with increase of the heating temperature, which impleis that grain boundaries and structure defects decreased with the rising temperature. It is clear from the experimental results that the positron annihilation technique may be also useful for studying some ultrafine polycrystalline materials.