Gabriele Zaffiro, in his new manuscript presents an assessment of the thermo-elastic behaviour of rutile based on X-ray diffraction data and direct elastic measurements available in literature. Gabriele’s results confirm that the quasi-harmonic approximation is not valid for rutile because rutile exhibits substantial anisotropic thermal pressure (i.e. the unit-cell parameters change significantly along isochors). He also introduces a series of formulations and a simple protocol to obtain thermodynamically consistent Equations of State for the volume and the unit-cell parameters for stiff materials, such as rutile.
The manuscript is now online and can be downloaded from the Mineralogical Magazine website