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Orientational ordering in C70. Evidence for three distinct phase transitions

✍ Scribed by Sheela K. Ramasesha; A.K. Singh; Ram Seshadri; A.K. Sood; C.N.R. Rao


Publisher
Elsevier Science
Year
1994
Tongue
English
Weight
382 KB
Volume
220
Category
Article
ISSN
0009-2614

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✦ Synopsis


Variable-temperature X-ray diffraction studies of CT0 suggest the occurrence of two phase transitions around 350 and 280 K where the hi&temperature phase is fee and the low-temperature phase is monoclinic, best described as a distorted hcp structure with a doubled unit cell, two like-phases (possibly hcp) seem to coexist in the 280-350 K range. Application of pressure gives rise to three distinct transitions associated with characteristic pressure coefficients, the extrapolated values of the transition temperatures at ambient pressure being around 340, 325 and 270 K. Pressure delineates closely related phases of CT0 just as in the case of Cso which exhibits two orientational phase transitions at h&h pressures.