Neutron diffraction on methane and hydrogen hydrates under high pressure

Gas hydrates are crystalline solids composed of water and gas. They have attracted considerable attention over the past decade both for their geophysical relevancy [1] and for their possible application to gas storage [2]. Pressure is a key parameter in the study of these systems as gas hydrates are believed to exist at pressure in nature and the gas content is found to increase in gas hydrates as their crystalline structure rearranges upon compression. In addition, high-pressure studies on gas hydrates offer new possibilities to explore water-gas interactions. We will present recent work on methane and hydrogen hydrates at high pressure performed by neutron diffraction in the GPa range [3]. Several issues including the gas content in the different high-pressure structures will be discussed.