High-pressure crystallography of methane: a low-temperature neutron diffraction study in the 1–5GPa range

H.E. Maynard (1) , J.S. Loveday (1) , S. Klotz (2) , C.L. Bull (1) , T.C. Hansen (3)

1 CSEC - SUPA Centre for Science at Extreme Conditions [Edinburgh]
2 IMPMC - Institut de minéralogie et de physique des milieux condensés
3 ILL - Institut Laue-Langevin

We report the preliminary results of our recent low-temperature, high-pressure neutron diffraction study of deuterated methane. Contrary to earlier spectroscopic studies of hydrogenous methane, we find no evidence of any structural change between 1 and 5GPa at 25K and show that the diffraction patterns can be indexed and refined with the room temperature high-pressure structure of phase A. Our results suggest that either methane shows a remarkably strong isotopic effect or the spectroscopic changes observed are not indicative of structural phase transitions.

Mots clés: high-pressure; methane; structure

Domaines: Autre [cond-mat.other]

H.E. Maynard, J.S. Loveday, S. Klotz, C.L. Bull, T.C. Hansen. High-pressure crystallography of methane: a low-temperature neutron diffraction study in the 1–5GPa range. High Pressure Research, 2009, 29 (1), pp.125-128. ⟨10.1080/08957950802570459⟩. ⟨hal-00545210⟩