论文部分内容阅读
在室温下,固体C_(60)呈面心立方结构,因分子快速旋转故取向无序.在250—260K,固体C_(60)分子的晶体结构出现了一级相变,在简立方晶格,降低的空间群对称性至P_a~(?),但即使在有序相,短程无序仍持续到较低的温度.不久前,Shi等报道了C_(60)单晶的弹性力学研究结果,对纯化的fcc晶体,杨氏模量在260K的一级相变点有8%的跳跃,而在160K存在着一个与频率有关的反常弹性形变(来自随时间变化的压力弛豫),而Tycko等提出的与自旋-晶格
At room temperature, the solid C_ (60) has a face-centered cubic structure with disordered orientation due to rapid molecular rotation. The first-order phase transition occurs in the crystal structure of the solid C_ (60) molecule at 250-260 K, , Decreasing the space group symmetry to P_a ~ (?), But even in the ordered phase, short-range chaos continues to lower temperatures. Not long ago, Shi et al. Reported the C_ (60) single-crystal elastic mechanics , Whereas for purified fcc crystals there is a 8% jump in Young’s modulus at the first order transformation point of 260K and at 160K there is a frequency dependent anomalous elastic deformation (from pressure relaxation over time) Tycko et al. Proposed a spin-lattice