HfSiO4 (hafnon) can be used as a layer environmental barrier coating (EBC) materials placed between silicon dioxide and hafnia. Hafnon has a good lattice thermal expansion matching between silica and hafnia and can prevent oxygen diffusion in EBCs, thereby potentially lengthening the lifetime of EBCs. In this work, we conduct a comprehensive investigation of mechanical, thermodynamic and thermal transport properties of hafnon using first-principles density functional theory (DFT) calculations and compare our results to experiments performed on this material. The volumetric coefficients of thermal expansion (CTE) calculated by the quasi-harmonic approximation are in the range 9.18 - 19.07×10-6 K-1, when the temperature increases from 300 to 1500 K, in agreement with X-Ray Diffraction and dilatometer measurements. The thermal conductivity is nearly 10 Wm-1K-1 at room temperature (RT) using the Boltzmann transport theory. The time-domain thermoreflectance technique utilized to measure thermal conductivity yields 12.4 Wm-1K-1. The mechanical properties, such as bulk modulus and elastic constants are also compared between the first-principles calculations and the RT nanoindentation technique. This study validates our computational approach and can be used to further study thermomechanical properties of other high-temperature oxides.
5:00 PM–7:00 PM Apr 23, 2019 (US - Arizona)
PCC North, 300 Level, Exhibit Hall C-E