Mechanisms of Mono‐Vacancy and Oxygen Permeability in Y2SiO5 Orthosilicate Studied by First‐Principles Calculations
Mechanisms of Mono‐Vacancy and Oxygen Permeability in Y2SiO5 Orthosilicate Studied by First‐Principles Calculations
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DOI：
10.1111/j.1551-2916.2011.05046.x
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发表时间：
2012-03
影响因子：
3.9
通讯作者：
B. Liu;Jiemin Wang;Fangzhi Li;Jingyang Wang;Yanchun Zhou
中科院分区：
文献类型：
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作者：
B. Liu;Jiemin Wang;Fangzhi Li;Jingyang Wang;Yanchun Zhou
了解Y2SiO5中原生点缺陷和氧空位扩散的机理对评价其作为环境和热障涂层（ETBC）的性能具有重要意义。在目前的第一性原理计算中，我们发现氧空位是主要的空位种类，并且更倾向于在SiO4四面体内部的氧晶格位点上形成，而不是在间隙的非硅键氧位点上形成。计算得到的Y2SiO5中缺陷形成能和单空位浓度明显依赖于各元素的化学势。结果表明，通过控制材料合成中的化学环境，可以定制Y2SiO5中的空位种类。最后，理论模拟表明，氧空位自扩散在Y2SiO5中具有与SiO2和Al2O3相当的高能垒。结果表明，Y2SiO5具有较低的氧渗透性，进一步增强了其作为ETBC材料的应用前景。
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.