SINTEF Industry, Sustainable Energy Technology, P.O. Box 124 Blindern, Oslo, NO-0314, Norway.
Phys Chem Chem Phys. 2018 Jun 13;20(23):16209-16215. doi: 10.1039/c8cp00168e.
Defect segregation and space-charge formation were investigated for a (0 2 1)[1 0 0] symmetric tilt grain boundary in Y-doped BaCeO3. Density functional theory calculations according to the PBE+U formalism were used to calculate segregation energies for protons, oxygen vacancies and Y-acceptor dopants from the bulk to the grain boundary core. Defect concentration and potential profiles across the grain boundary were obtained from thermodynamic space-charge models. Oxygen vacancies were found to exhibit a particularly exothermic segregation energy of up to -1.66 eV while protons exhibited segregation energies in the range of -0.47 eV to -0.93 eV. The grain boundary was determined to be predominated by protons below 800 K in 3% H2O and the corresponding space-charge potential was 0.4-0.7 V under the Mott-Schottky approximation. The role of electronic defects in the space-charge properties was evaluated, and it was substantiated that electron conduction along the grain boundary could become evident under reducing conditions.
对掺钇 BaCeO3 中（021）[100]对称倾斜晶界的缺陷偏析和空间电荷形成进行了研究。采用基于 PBE+U 形式的密度泛函理论计算，从体相到晶界核心计算了质子、氧空位和 Y 受主掺杂剂的偏析能。从热力学空间电荷模型获得了晶界两侧的缺陷浓度和电势分布。氧空位表现出高达-1.66 eV 的特别放热偏析能，而质子的偏析能在-0.47 eV 到-0.93 eV 之间。在 3%H2O 中，低于 800 K 时，晶界主要由质子占据，根据 Mott-Schottky 近似，相应的空间电荷势为 0.4-0.7 V。评估了电子缺陷在空间电荷特性中的作用，并证实了在还原条件下，电子沿晶界的传导可能变得明显。
