First-principle calculations and experimental investigations of thermal barrier coating on (AlxY1-x)TaO4 ceramics

Abstract

In this paper, the crystal structure models of (AlxY1-x)TaO4 were constructed using the virtual crystal approximation method, and the crystal structure, electronic structure, and mechanical properties were calculated with the first-principle calculations. The bulk specimens were synthesized by hot-press sintering method, and their physical phase structures as well as mechanical properties were tested. Moreover, the calculated results were validated using the experimental data. Calculated results indicate that as Al content increases, the energy band gap of (AlxY1-x)TaO4 crystal decreases, the total density of states for Fermi energy level increases, the chemical stability of the compound decreases, and the chemical bonding between atoms diminishes. In accordance with the variation law of electronic structure, the Young's modulus, shear modulus, bulk modulus, and Vickers hardness of the compounds decrease as the Al content rises, whereas Poisson's ratio rises, indicating that the materials are more susceptible to deformation. In addition, the Young's modulus of (AlxY1-x)TaO4 (127–150 GPa) is lower than that of YSZ, and the hardness values (8.8–11.3 GPa) are comparable to those of YSZ, indicating that the material has high stress-strain tolerance.