Abstract CuBiW2O8 (CBTO), a theoretically predicted, recently synthesized novel quaternary metal oxide, has been identified as a promising solar light absorber. In the present paper, the surface properties of CBTO are studied to further examine the applicability of the material for solar energy applications. Surface studies of quaternary oxides via first principles methods are rare in the literature. We present here a systematic approach to identifying stable surfaces and the origin of their stability. First, the emergence of the electronic properties from the interplay of cations is explored in bulk CBTO. Calculated XRD data is used to label the surfaces on the experimental XRD plot. For the dominant low-index stoichiometric surfaces, we calculate surface bond strengths, cleaving energies, and surface energies via the slab model within periodic boundary conditions. To calculate the surface energies of a quaternary oxide such as CBTO, we review the existing methodologies and propose a guideline for defining the lower and upper bounds of the slab thickness used in the linear fit model. Surface energies are then used to predict the equilibrium crystal shape via Wulff construction.

中文翻译：

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CuBiW2O8 的低指数化学计量表面

摘要 CuBiW2O8 (CBTO) 是一种理论上预测的、最近合成的新型四元金属氧化物，已被确定为一种有前途的太阳能光吸收剂。在本论文中，研究了 CBTO 的表面特性，以进一步检验该材料在太阳能应用中的适用性。通过第一性原理方法对四元氧化物的表面研究在文献中很少见。我们在此介绍了一种识别稳定表面及其稳定性起源的系统方法。首先，在块状 CBTO 中探索了阳离子相互作用产生的电子特性。计算的 XRD 数据用于标记实验 XRD 图中的表面。对于主要的低指数化学计量表面，我们计算表面键强度、切割能、和表面能通过周期性边界条件下的板坯模型。为了计算四元氧化物（如 CBTO）的表面能，我们回顾了现有的方法并提出了用于定义线性拟合模型中使用的板坯厚度下限和上限的指南。然后使用表面能通过 Wulff 构造预测平衡晶体形状。