Investigation on the Thermal–Mechanical Properties of YbRESiO5 (RE = Yb, Eu, Gd, Ho, Tm, Lu, Y, Sc): First-Principles Calculations and Thermal Performance Experiments

Abstract

Environmental barrier coatings are critically needed in the future to safeguard SiC-based ceramic matrix composites (SiC CMCs) used in gas turbines. Element doping of rare earth monosilicates could further improve the properties of the coating. The crystal structure, elastic properties, and resistance to water vapor corrosion of Yb2SiO5 and YbRESiO5 (where RE = Sc, Y, Eu, Gd, Ho, Tm, Lu) were examined in this study using first-principles calculations. When RE is Yb, the material is Yb2SiO5. Based on the outcomes of the calculation, we prepared YbRESiO5 (RE = Sc, Yb, Eu) and studied the thermodynamic properties. The findings show that YbReSiO5’s resistance to water vapor corrosion is as follows: YbLuSiO5 < YbEuSiO5 < YbGdSiO5 < YbYSiO5 < Yb2SiO5 < YbTmSiO5 < YbHoSiO5 < YbScSiO5. YbScSiO5 has a lower unit cell volume, average Re-O bond length, and thermal expansion coefficient than Yb2SiO5, while YbEuSiO5 has the reverse pattern. Moreover, of the eight materials, YbScSiO5 has the greatest elastic modulus and lattice distortion. After doping with Eu, YbEuSiO5 exhibits a decrease in thermal conductivity by nearly thirty percent compared to Yb2SiO5, due to the formation of oxygen vacancies. The development of environmental barrier coating materials may benefit from these discoveries.