物理化学学报 >> 1995, Vol. 11 >> Issue (11): 991-996.doi: 10.3866/PKU.WHXB19951107

研究论文 上一篇    下一篇

C60固体中的相变

徐志瑾,严继民   

  1. 中国科学院化学研究所,北京 100080
  • 收稿日期:1994-12-31 修回日期:1995-03-05 发布日期:1995-11-15
  • 通讯作者: 严继民

Phase Transition in Solid C60

Xu Zhi-Jin,Yan Ji-Min   

  1. Institute of Chemistry,Academia Sinica,Beijing 100080
  • Received:1994-12-31 Revised:1995-03-05 Published:1995-11-15
  • Contact: Yan Ji-Min

摘要:

本文用(exp-6-1)势对固体C60中分子间的相互作用进行计算,给出常温及常温以下固体C60中分子存在的状态. 计算表明,常温下C60高速旋转,随着温度降低,旋转速度逐渐减小,并且旋转轴向也逐渐趋于单一. 当降到~260K时发生一级相变,此时FCC晶胞中(0,0,0)、(1/2,1/2,0)、(0,1/2,1/2)及(1/2,0,1/2)四套格点上的分子各只绕[111]、[111]、[111]及[111]三重轴旋转,C60晶体从FCC结构变为SC结构;当温度继续下降到一定程度(~90K)时,发生二级相变,C60由晶态变为玻璃态.

关键词: C60, 相变, (exp-6-1)势模型, 取向相变

Abstract:

The interactions between C60 molecules in solid state are calculated by the potential model (exp-6-1). The states of C6o molecules in solid are given at room temperature and at lower temperature. C60 molecule rotates rapidly at room temperature; the rotation rate decreases and the rotational axes tend to ordering as temperature becomes lower. And at about 260K the structure undergoes a first-order phase transiton from the high-temperature FCC phase to the ordered SC structure. The molecule equivalence above 260K is now broken by rorating the four molecules through the same angle but around different <111> axes: the molecule at (0,0,0) around [111], that at (1/2,1/2,0) around [111], that at (0,1/2,1/2) around [111] and at (1/2,0.1/2) around [111]. At about 90K, the system undergoes a second-order phase transition-----glass transition.

Key words: C60, Phase transition, (exp-6-1)potential model, Orientational transition