X-ray study of two-phase coexistence in a C{sub 60} single crystal through the cubic-cubic phase transition at 260 K
X-ray study of two-phase coexistence in a C{sub 60} single crystal through the cubic-cubic phase transition at 260 K
复制标题
X 射线研究 C{sub 60} 单晶在 260 K 下通过立方-立方相变的两相共存
DOI：
10.1103/physrevb.55.5678
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发表时间：
1997
影响因子：
3.7
通讯作者：
S. Moss
中科院分区：
文献类型：
--
作者：
P. Wochner;X. Xiong;P. Chow;S. Moss
用同步辐射和自制的X射线衍射方法研究了C{sub 60}在260 K左右的一级立方相变。在这个范围内，（旋转无序，fcc）相，晶格参数为14.14埃，在除第一次冷却之外的所有循环中观察到晶格参数为14.08 {埃}的（取向有序，sc）相共存，并且在关于布拉格强度、宽度、镶嵌扩展的实验数据的背景下对其进行讨论，和峰值位置（晶格参数）。这种转变的特点也是一个可测量的滞后的顺序参数。与体积变化相关的弹性相互作用和不同的颗粒（马赛克块）尺寸分布似乎可以解释我们的观察结果。在解释的行为的基本（hkscr（1）-未混合）和有序（hkscr（1）-混合宇称）的强度低于相变，这表明，主要的C{sub 60}取向角移动稍微从98{度}上降低温度的一个更高的角度。{版权} {美国物理学会}
The first-order cubic-to-cubic phase transition in C{sub 60} at {approximately}260 K is studied by both synchrotron and in-house x-ray diffraction through three thermal cyclings. A range in which the high-temperature (rotationally disordered, fcc) phase with lattice parameter of 14.14 {Angstrom} and the low-temperature (orientationally ordered, sc) phase with lattice parameter of 14.08 {Angstrom} coexist was observed in all cyclings except the first cooling and it is discussed in the context of the experimental data on Bragg intensities, widths, mosaic spreads, and peak positions (lattice parameters). This transition is also characterized by a measurable hysteresis in the order parameter. Elastic interactions, associated with the volume change, and a varying particle (mosaic block) size distribution appear to account for our observations. In explanation of the behavior of the fundamental (hkscr(l)- unmixed) and ordering (hkscr(l)-mixed parity) intensities below the phase transition, it is suggested that the major C{sub 60} orientation angle moves slightly towards a higher angle from 98{degree} on lowering the temperature. {copyright} {ital 1997} {ital The American Physical Society}