Effect of stress on melting of rhombohedral bismuth
- Carnegie Inst. of Washington, Argonne, IL (United States). High Pressure Collaborative Access Team (HPCAT). Geophysical Lab.
In this paper, pressure-induced melting of rhombohedral bismuth (Bi-I) has been investigated in the solid pressure medium of NaCl and the hydrostatic medium of neon at high temperatures by in-situ synchrotron x-ray diffraction. Upon compression from ~ 0.7 GPa to 3.2 GPa at (or below) 489 K, Bi-I melts into a liquid between ~ 1.2 and 1.6 GPa in the solid pressure medium and then crystallizes into Bi-IV at ~ 2.9 GPa. However, at the same temperature of 489 K, Bi-I transforms to a crystalline phase (Bi-II' or Bi-II) at ~ 1.8 GPa under hydrostatic conditions, followed by a transformation to Bi-IV at 2.5 GPa. Our x-ray diffraction results indicate that the melting of Bi-I at (or below) 489 K is due to the stress. There is a stress effect on the structural deformation of Bi-I when the solid pressure medium is used, viz., pressure-dependent c/a for Bi-I in the solid pressure medium is larger or smaller than that under hydrostatic conditions. According to the classical nucleation theory, the stress provides an additional driving force, leading to the reduction of the free energy barrier in the formation of liquid nuclei and thus melting temperature. Finally and additionally, the melting of Bi-I may also be favored by heterogeneous nucleation of the liquid on the boundary between the solid medium and the Bi sample, further contributing to the reduction of the melting temperature.
- Research Organization:
- Carnegie Inst. of Science, Argonne, IL (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Basic Energy Sciences (BES); USDOE National Nuclear Security Administration (NNSA); National Science Foundation (NSF)
- Grant/Contract Number:
- FG02-99ER45775; NA0001974; FG02-94ER14466; AC02-06CH11357; EAR 11-57758; EAR-1128799
- OSTI ID:
- 1466209
- Alternate ID(s):
- OSTI ID: 1361836
- Journal Information:
- Applied Physics Letters, Vol. 110, Issue 16; ISSN 0003-6951
- Publisher:
- American Institute of Physics (AIP)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
Web of Science
A reversible transition in liquid Bi under pressure
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journal | January 2018 |
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