材料期刊网

Understanding the mechanisms of native point defects and oxygen-vacancy diffusion in Y2SiO5 is important to evaluate its performance as environmental and thermal barrier coating (ETBC). In the present first-principles calculations, we show that oxygen vacancy is the predominant vacancy species and prefers to form on the oxygen lattice sites inside SiO4 tetrahedra instead of on the interstitial non-silicon-bonded oxygen site. The calculated defect formation energy and concentration of mono-vacancies in Y2SiO5 obviously depend on the chemical potential of each element. The results suggest that it is possible to tailor the vacancy species in Y2SiO5 by controlling the chemical environment in material synthesis. Finally, theoretical simulation revealed that the self-diffusion of oxygen vacancy has high energy barriers in Y2SiO5, which is comparable to those in SiO2 and Al2O3. The result demonstrates low oxygen permeability in Y2SiO5 and further strengthens its promising applications as ETBC material.