Lattice collapse in mixed-valence samarium fulleride Sm(2.75)C(60) at high pressure.
Lattice collapse in mixed-valence samarium fulleride Sm(2.75)C(60) at high pressure.
复制标题
高压下混合价钐富勒化物 Sm(2.75)C(60) 的晶格塌陷。
DOI：
10.1039/b405511j
复制
发表时间：
2004
影响因子：
4
通讯作者：
K. Prassides
中科院分区：
文献类型：
--
作者：
J. Arvanitidis;K. Papagelis;S. Margadonna;K. Prassides
Sm(2.75)C(60)在4.2-32K的常压下表现出较大的负热膨胀行为，这是从较大的Sm(2+)到较小的Sm(2.3+)离子的准连续价态变化的结果。本文利用粉末同步辐射X射线衍射技术，在常温高压下研究了0-6 Gpa压力范围内的压缩行为。Sm价从+2.3到+3的突然转变引起了一个突然的滞后相变，伴随着体积的急剧下降(约=6.0%)和颜色从黑色到金色的变化。这种行为是Sm(2.75)C(60)这样的高度相关的绝缘体的典型行为，使Sm(2.75)C(60)成为这类材料中第一个已知的基于分子的成员。
Sm(2.75)C(60) displays large negative thermal expansion behaviour in the temperature range 4.2-32 K at ambient pressure as a result of a quasi-continuous valence change from the larger Sm(2+) towards the smaller Sm(2.3+) ion. Here we use the powder synchrotron X-ray diffraction technique at ambient temperature and elevated pressures to study the compression behaviour in the pressure range 0-6 GPa. An abrupt hysteretic phase transition, accompanied by a dramatic volume decrease (approximately =6.0%) and a change in colour from black to golden was found at approximately =4 GPa induced by a sudden Sm valence transition from +2.3 towards +3. Such behaviour is typical of highly correlated Kondo insulators like SmS and makes Sm(2.75)C(60) the first known molecular-based member of this fascinating class of materials.