Heat Transport in Deep Planetary Interiors – HT-DPI

Presently, the experimental investigation of thermal properties at high pressures and temperatures has relied on the use of large volume press technology. This in turn has placed an upper bound on the maximum pressure to ~20 GPa. This is a severe limitation and a critical problem for addressing the thermal properties of materials under extreme thermodynamic conditions. Thus, the goal of this research program is to develop techniques and methodologies for the determination of heat transfer mechanisms in insulating materials at very high pressures and temperatures. Specifically, we intend to investigate thermal conductivity and thermal diffusivity of samples compressed into diamond anvil cell, with the aim of enlarging the pressure and temperature ranges over which these properties can be measured.
To address the lattice conduction, we propose using inelastic x-ray scattering measurements, while we will collect optical-visible and near-infrared absorption spectra to characterize the radiative heat transfer. Novel techniques, based on short-pulsed laser, aiming at the determination of thermal diffusivity in diamond anvil cell will be also developed and applied to complement the above proposed measurements.
While the developed techniques will have a large range of applications, as first scientific case, we intend to provide experimental data to better constrain the nature of the dynamical processes active within the interiors of the Earth and telluric planets. In particular, we will study the two main component of Earth’s lower mantle and of the silicate layer of telluric planets at Mabar pressure, the iron-bearing oxides (Mg,Fe)O-ferropericlase and (Mg,Fe)SiO3-perovskite, with the aim of measuring thermal conductivity and thermal diffusivity as a function of the major thermodynamic variables: pressure, temperature and composition.
This interdisciplinary approach, at the frontier between solid-state physics, geophysics and planetary science, will provide important information necessary for a detailed understanding of the heat transfer mechanisms within the Earth and telluric planets, and hence will supply parameters essential to the geodynamical modelling of deep planetary interiors.