Pressure-Induced Phase Transitions of C70 Nanotubes

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• 作者：Dedi Liu ; Mingguang Yao ; Lin Wang ; Quanjun Li ; Wen Cui ; Bo Liu ; Ran Liu ; Bo Zou ; Tian Cui ; Bingbing Liu ; Jing Liu ; Bertil Sundqvist ; Thomas Wa虋gberg
• 刊名：Journal of Physical Chemistry C
• 出版年：2011
• 出版时间：May 12, 2011
• 年：2011
• 卷：115
• 期：18
• 页码：8918-8922
• 全文大小：821K
• 年卷期：v.115,no.18(May 12, 2011)
• ISSN：1932-7455

文摘

Single crystalline C₇₀ nanotubes having a face-centered-cubic (fcc) structure with diameters on a nanometer scale were synthesized by a facile solution method. In situ high pressure Raman spectroscopy and X-ray diffraction have been employed to study the structural stability and phase transitions of the pristine sample. We show that the molecular orientation-related phase transition from the fcc structure to a rhombohedral structure occurs at about 1.5 GPa, which is 1 GPa higher than in bulk C₇₀. Also, the C₇₀ molecules themselves are more stable in the nanotubes than in bulk crystals, manifested by a partial amorphization at 20 GPa. The crystal structure of C₇₀ nanotubes could partially return to the initial structure after a pressure cycle above 30.8 GPa, and the C₇₀ molecules were intact up to 43 GPa. The bulk modulus of C₇₀ nanotubes is measured to be 50 GPa, which is twice larger than that of bulk C_70.