X-ray study of two-phase coexistence in a C{sub 60} single crystal through the cubic-cubic phase transition at 260 K
- Department of Physics and Texas Center for Superconductivity, University of Houston, Houston, Texas 77204-5506 (United States)
The first-order cubic-to-cubic phase transition in C{sub 60} at {approximately}260 K is studied by both synchrotron and in-house x-ray diffraction through three thermal cyclings. A range in which the high-temperature (rotationally disordered, fcc) phase with lattice parameter of 14.14 {Angstrom} and the low-temperature (orientationally ordered, sc) phase with lattice parameter of 14.08 {Angstrom} coexist was observed in all cyclings except the first cooling and it is discussed in the context of the experimental data on Bragg intensities, widths, mosaic spreads, and peak positions (lattice parameters). This transition is also characterized by a measurable hysteresis in the order parameter. Elastic interactions, associated with the volume change, and a varying particle (mosaic block) size distribution appear to account for our observations. In explanation of the behavior of the fundamental (hkscr(l)- unmixed) and ordering (hkscr(l)-mixed parity) intensities below the phase transition, it is suggested that the major C{sub 60} orientation angle moves slightly towards a higher angle from 98{degree} on lowering the temperature. {copyright} {ital 1997} {ital The American Physical Society}
- Research Organization:
- Brookhaven National Lab. (BNL), Upton, NY (United States)
- DOE Contract Number:
- AC02-76CH00016
- OSTI ID:
- 467386
- Journal Information:
- Physical Review, B: Condensed Matter, Vol. 55, Issue 9; Other Information: PBD: Mar 1997
- Country of Publication:
- United States
- Language:
- English
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