Chi Dam Hieu, Iwasa Y, Takata M
Japan Advanced Institute of Science and Technology, Tatsunokuchi, Ishikawa 923-1292, Japan.
J Nanosci Nanotechnol. 2006 Dec;6(12):3888-92. doi: 10.1166/jnn.2006.667.
Rare-earth-metal-doped fullerides with a nominal composition of R3C70 (R = Sm, Eu, Yb) adopt a pseudomonoclinic structure in which C70 dimers glued with rare-earth ions are involved. High-temperature powder X-ray diffraction experiments revealed that the dimers undergo reversible first-order structural phase transitions, associated with reduction of the unit cell volume, similar to the results observed in previous high-pressure experiments. Structural analyses showed that C70 molecules are realigned to form closely packed structures, causing a reduction of volume at high temperature. The derived charge density map indicates that the transitions can be regarded as reversible structural changes from fullerene dimers to monomers. These features are ascribed to the unique bonding nature of rare-earth C70 compounds.
标称组成为R3C70（R = 钐、铕、镱）的稀土金属掺杂富勒化物采用一种伪单斜结构，其中涉及与稀土离子相连的C70二聚体。高温粉末X射线衍射实验表明，这些二聚体经历了可逆的一级结构相变，这与晶胞体积的减小有关，类似于先前在高压实验中观察到的结果。结构分析表明，C70分子重新排列形成紧密堆积结构，导致高温下体积减小。推导得到的电荷密度图表明，这些转变可被视为从富勒烯二聚体到单体的可逆结构变化。这些特征归因于稀土C70化合物独特的键合性质。
