Phase transitions in single crystal tubes formed from C60 molecules under high pressure

Pure single crystal tubes formed from C-60 molecules, with a face-centered cubic (fcc) structure were fabricated by a liquid-liquid interfacial precipitation method using C-60 powder. A bulk transition from fcc to a simple cubic structure and a surface transition from (1 x 1) to (2 x 2) have been observed around 246 K (bulk transition temperature T-B) and 214 K (surface transition temperature T-S), respectively, during the measurement of the temperature dependence of electrical resistance. The initiation of the two transitions under pressure was investigated using a piston cylinder high pressure apparatus and it was found that both T-B and T-S increase with increasing pressure. And the C-60 molecules at the surface of the tube exhibit the same behavior of that in the bulk at a pressure of about 2.1 GPa. (C) 2012 Elsevier Ltd. All rights reserved.