High-pressure thermal properties of liquid, solid and amorphous H2O

Abstract:

We have developed a new technique to measure thermal conductivity and heat capacity of any insulator compressed inside a diamond anvil cell. To date, the product of heat capacity and thermal conductivity has been measured with 15% uncertainty between 160 K and 300 K at ambient pressure inside a diamond cell. The method uses Joule heating of a platinum thin-film that is pressed against the sample. Electrical current oscillates at frequencies up to 300 kHz and we infer the amplitude of temperature oscillation via a third-harmonic voltage measurement. In the next four months, measurements will be performed on H­₂O at variable pressure and temperature, using heating and cooling timescales that range from hours to microseconds in order to study both equilibrium and metastable states.