Sound velocity, melting curve, and phase diagram of dense hot ammonia
Abstract
The sound velocity, melting curve and phase diagram of ammonia have been investigated from 15 to 55 GPa and up to 3300 K using Brillouin spectroscopy of CO2 laser-heated ammonia samples in a diamond anvil cell. The melting transition was unambiguously identied from the appearance of the Brillouin peaks of uid ammonia upon temperature increase, the latter being well resolved from that of the solid phase. Our melting temperatures are in good agreement with previous measurements and theoretical predictions. Within experimental uncertainties, we do not observe any discontinuous variation of the sound velocity nor of the slope of the melting curve at the passage from the plastic phase III to the superionic phase α-SI, which is consistent with most previous experimental and theoretical results. We also nd no evidence for the superionic γ-SI phase with uid-like elastic behavior reported in a recent work, and suggest that it was mistaken with the liquid phase.
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BibTeX
@article{guigue2026sound,
title = {{Sound velocity, melting curve, and phase diagram of dense hot ammonia}},
author = {Bastien Guigue and Keevin Béneut and Sandra Ninet and Marc Morand and Yiuri Garino and Gilles Minier and Philippe Rosier and Frédéric Datchi},
journal = {Physical Review B},
year = {2026},
month = may,
doi = {10.1103/d6tt-2j8m},
url = {https://hal.science/hal-05732806v1},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Sound velocity, melting curve, and phase diagram of dense hot ammonia
AU - Bastien Guigue
AU - Keevin Béneut
AU - Sandra Ninet
AU - Marc Morand
AU - Yiuri Garino
AU - Gilles Minier
AU - Philippe Rosier
AU - Frédéric Datchi
PY - 2026
DA - 2026/05/22
JO - Physical Review B
DO - 10.1103/d6tt-2j8m
UR - https://hal.science/hal-05732806v1
AB - The sound velocity, melting curve and phase diagram of ammonia have been investigated from 15 to 55 GPa and up to 3300 K using Brillouin spectroscopy of CO2 laser-heated ammonia samples in a diamond anvil cell. The melting transition was unambiguously identied from the appearance of the Brillouin peaks of uid ammonia upon temperature increase, the latter being well resolved from that of the solid phase. Our melting temperatures are in good agreement with previous measurements and theoretical predictions. Within experimental uncertainties, we do not observe any discontinuous variation of the sound velocity nor of the slope of the melting curve at the passage from the plastic phase III to the superionic phase α-SI, which is consistent with most previous experimental and theoretical results. We also nd no evidence for the superionic γ-SI phase with uid-like elastic behavior reported in a recent work, and suggest that it was mistaken with the liquid phase.
SN - 2469-9950
SN - 2469-9969
ER -