Feasibility of in situ neutron diffraction studies of non-crystalline silicates up to pressures of 25 GPa

There is an increasing interest in the structural modifications found in liquids and amorphous systems as a function of pressure. Neutron diffraction is a key technique for determining these structures, but its application in high pressure studies remains in its infancy. Recent developments now permit in situ neutron scattering studies of amorphous materials to very high pressure conditions. Here we present new data for MgO-SiO₂ and SiO₂ glasses collected at up to 8.6 and 24 GPa respectively, using two distinct high pressure anvil geometries. The data collected on the MgO-SiO₂ system appear to be reliable, and suggest strong changes in the chemical ordering. In contrast, the higher pressure SiO₂ data highlight significant difficulties in performing appropriate corrections for pressure-dependent background and attenuation effects. These challenges are discussed, and future improvements to the technique are proposed.