Modelling of electronic and structural strain effects in grain boundaries of semiconducting oxides

通过基于密度泛函理论（DFT）和原子模型的电子结构计算，研究了机械应力条件对压电氧化物中掺杂和未掺杂晶界电子电导率的影响。计算的目的是模拟不同取向的晶界（GB）作为机械应变，温度和氧分压的函数的化学和结构重建。我们的目标是模拟外部应变对GB内的电子态密度的影响。在这里，它是特别感兴趣的，如何机械和电场耦合到掺杂剂的分布，开放体积和晶界的电子结构。详细检查的双晶安排的不同取向的晶界（倾斜和扭曲边界）单轴和多轴机械负荷的计划。此外，热处理机械负荷下的晶界性质的影响，以及结构重排过程的特征时间尺度将估计通过计算的激活势垒扩散运输的内在和外在的缺陷在该地区的机械加载晶界。为了模拟微观结构参数对所观察到的效果的影响，分子静力学和分子动力学模拟的基础上的经典原子间相互作用势计划。 从长远来看，模拟的目的是确定和量化这些物理参数，这是必要的模型的机械可调组件的特性

The influence of mechanical stress conditions on the electronic conductivity of doped and undoped grain boundaries in piezoelectric oxides is investigated by means of electronic structure calculations based on density functional theory (DFT) and atomistic modelling. The calculations aim for modelling the chemical and structural reconstruction of grain boundaries (GB) of different orientations as function of mechanical strain, temperature and oxygen partial pressure. The goal is to simulate the influence of external strain on the electronic density of states within the GB. Here, it is of special interest, how mechanical and electrical fields couple to the distribution of dopants, open volume and the electronic structure of grain boundaries. Detailed examinations of bicrystal-arrangements for grain boundaries of different orientation (tilt and twist boundaries) upon uniaxial and multi-axial mechanical load are planned. Additionally, the influence of heat treatment under mechanical load on grain boundary properties as well as the characteristic time scales for structural rearrangement processes will be estimated by means of calculated activation barriers for diffusive transport of intrinsic and extrinsic defects in the area of mechanically loaded grain boundaries. In order to model the influence of microstructural parameters on the observed effects, molecular statics and molecular dynamics simulations base on classical interatomic potentials are planned. In perspective, the simulations aim to identify and to quantify those physical parameters, which are necessary to model the characteristics of mechanically tunable components