K在C_(60)单晶中的扩散通量研究

Study on the Diffusion Flux of K in C 60 Single Crystal.

通过电阻率测量研究了Ｋ原子在Ｃ６０单晶中的扩散深度与时间的关系，得出温度为２３０℃时Ｋ原子在Ｃ６０单晶中的扩散系数约为１０－１５ｍ２ｓ－１．由扩散系数估算出制备０．１ｍｍ厚Ｋ３Ｃ６０单晶约需１４５２小时扩散时间，而１ｍｍ厚单晶约需１６年，因而毫米级Ｋ３Ｃ６０单晶几乎是不可能制成的，对Ｋ原子扩散通量的计算结果表明，要使样品中（尤其是表面附近）不形成Ｋ６Ｃ６０相，扩散初期样品附近Ｋ蒸气的压强不宜超过１×１０－６Ｔｏｒ，并应随时间的（－１／２）次方而减小．在这个工作基础上，对文献中一些矛盾的结果作了较为满意的解释．

The relationship between diffusion depth of K in the C 60 single crystal and diffusion time was researched through the electrical resistivity measurements. Diffusion coefficient of about 10 -15 m 2s -1 was deduced. Diffusion time for the preparation of 0.1mm and 1.0mm thickness K 3C 60 single crystal was calculated to be about 1452 hours and 16 years respectively. In order to prevent the specimen from formating K 6C 60 , the calculated flux of K in the K 3C 60 single crystal demonstrated that the vapour pressure of K around the specimen should be no more than 1×10 -16 Torr in the initial period of diffusion. Based on these works, some inconsistent results in the literatures were successfully explained.