Institute of Physical Chemistry, RWTH Aachen University, 52074 Aachen, Germany.
Phys Chem Chem Phys. 2009 Nov 21;11(43):9939-69. doi: 10.1039/b904100a. Epub 2009 Aug 21.
The thermodynamics of space-charge formation at grain boundaries in acceptor-doped SrTiO(3) is examined. Thermodynamic models of varying complexity are developed, which predict the space-charge potential as a function of thermodynamic variables, such as dopant concentration, temperature and oxygen partial pressure. Based on the results, limits to the space-charge potential that can arise at a grain boundary and strategies for tuning the space-charge potential are discussed. With literature equations linking the space-charge potential to electrical properties, one specific thermodynamic model is subsequently applied to electrical impedance data reported in the literature for tilt bicrystal samples of Fe-doped SrTiO(3). The thermodynamic driving energies for space-charge formation obtained from the analysis are examined as a function of tilt misorientation angle, in order to explore the relationship between driving energy and interface atomistic structure. In addition, the capabilities and deficiencies of the entire approach (from driving energies via space-charge potentials to electrical properties), with regard to predicting experimental behaviour, are demonstrated.
研究了受主掺杂 SrTiO(3) 晶界处空间电荷形成的热力学。开发了具有不同复杂性的热力学模型，这些模型预测了空间电荷势作为掺杂浓度、温度和氧分压等热力学变量的函数。基于这些结果，讨论了晶界处空间电荷势的极限以及调节空间电荷势的策略。通过将空间电荷势与电性能联系起来的文献方程，随后将一个特定的热力学模型应用于文献中报道的 Fe 掺杂 SrTiO(3) 倾斜双晶样品的电阻抗数据。从分析中获得的空间电荷形成的热力学驱动力作为倾斜偏转角的函数进行了研究，以探索驱动力与界面原子结构之间的关系。此外，还展示了整个方法（从驱动力通过空间电荷势到电性能）在预测实验行为方面的能力和局限性。
