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Title: Phase Transition of Heptane under Pressure

Journal Article · · Journal of Physical Chemistry. C

A solid-to-solid phase transition was discovered in n-heptane with an onset at a pressure of 1.7 ± 0.1 GPa, evidenced by a discontinuity in the pressure–volume equation of state obtained from synchrotron X-ray diffraction experiments conducted at room temperature. The phase transition also resulted in discontinuous shifts of vibrational peaks in the infrared spectra. No additional phase transitions were detected up to 10 GPa, contradicting an earlier claim of a phase transition at 3 GPa. Furthermore, the hydrostatic limit of heptane in a diamond anvil cell was estimated to be 3.5 GPa. Above that pressure, the stress state is not well-defined, which may explain prior reports of a phase transition at 7.5 GPa.

Research Organization:
Washington State Univ., Pullman, WA (United States); Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)
Sponsoring Organization:
USDOE Office of Science (SC), Basic Energy Sciences (BES). Materials Sciences & Engineering Division (MSE); USDOE National Nuclear Security Administration (NNSA), Office of Defense Programs (DP); USDOE Office of Science (SC), Basic Energy Sciences (BES)
Grant/Contract Number:
NA0003957; FG02-07ER46386; AC02-05CH11231; AC52-07NA27344
OSTI ID:
2305369
Alternate ID(s):
OSTI ID: 2315025; OSTI ID: 2325291
Report Number(s):
LLNL-JRNL-857175
Journal Information:
Journal of Physical Chemistry. C, Vol. 128, Issue 5; ISSN 1932-7447
Publisher:
American Chemical SocietyCopyright Statement
Country of Publication:
United States
Language:
English

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