Neutron diffraction studies of water and aqueous solutions under pressure

A summary is given of data obtained from neutron diffraction experiments on heavy water at elevated pressures and temperatures using three different types of pressure vessel. The pressure vessels were manufactured from (i) hard steel (EN24T), (ii) titanium-zirconium null alloy, and (iii) autofrettaged aluminium alloy (7075-T6). In cases (i) and (ii), hydraulic pressures up to 6 kbar were applied directly to the sample across the oil/aqueous solution interface. In case (iii) the pressurizing medium of argon gas was applied uniformly throughout the sample volume giving pressures up to 2 kbar at temperatures in the range 210C to 800C