Pressure and Temperature Evolution of the Structure of the Superconducting Na2CsC60 Fulleride
作者:Serena Margadonna、Craig M Brown、Alexandros Lappas、Kosmas Prassides、Katsumi Tanigaki、Kenneth D Knudsen、Tristan Le Bihan、Mohamed Mézouar
DOI:10.1006/jssc.1998.8159
日期:1999.7
7(1)%), is encountered. This phase was characterized as monoclinic with a=13.745(5) Å, b=14.224(6) Å, c=9.408(3) Å, and β=133.71(1)° (space group P21/a), isostructural with the low-temperature polymer phase of Na2RbC60. The cubic and polymeric phases of Na2CsC60 coexist up to 0.90 GPa. The pressure evolution of the monoclinic lattice constants a, b, and c to 8.63 GPa reveals the presence of substantial
Na 2 CsC 60富勒酸盐的结构性质已通过同步加速器X射线粉末衍射在环境压力和升高压力下进行了研究。还进行了高压下的补充中子衍射测量。尽管采用了缓慢的冷却程序,但即使在200 K下长时间放置,我们也没有发现在室温下冷却时单体→聚合物相变的证据。该结构即使在200 K长时间放置后仍严格保持立方。固体Na 2 CsC结构的压力依赖性60在环境温度下通过中子衍射达到0.56 GPa,通过同步加速器X射线衍射达到8.63 GPa。在环境压力下,该结构为原始立方,具有= 14.1329(3)Å(空间群Pa)。当达到0.76GPa的压力时,会遇到不完全过渡到低对称结构的现象,并伴有较大的体积减小(2.7(1)%)。该相的特征为a = 13.745(5)Å,b = 14.224(6)Å,c = 9.408(3)Å和β = 133.71(1)°(空间群P 2 1 / a)的单斜晶,同构Na 2 RbC