The energetics of mixing and defect ordering in solid solutions of fluorite-structured ThO$_{2}$ with oxides of trivalent cations (Sc, In, Y, Nd, La) are investigated by electronic density-functional-theory (DFT). Through DFT calculations of structures enumerated by lattice-algebra techniques, we identify the lowest-energy patterns for defect clustering for four separate dopant concentrations. The most stable structures are characterized by a repulsive interaction between nearest-neighbor vacancies on the oxygen sublattice. The enthalpies of formation with respect to constituent oxides are positive for all dopants considered, and show a tendency to decrease in magnitude as the size and electronegativity of the trivalent dopant decrease. Due to the small positive formation enthalpies and low oxygen-vacancy binding energy with La dopants, La$_{2}$O$_{3}$-ThO$_{2}$ solid solutions are predicted to have relatively high ionic conductivities relative to those for the other aliovalent dopants considered. Our results are compared with those for the more widely studied ZrO$_{2}$ and CeO$_{2}$ fluorite-structured solid solutions with trivalent cations.
翻译:在三价氧化物(Sc、In、Y、Nd、La)的含三价氧化物(Sc、In、Y、Nd、La)的固溶溶液中,混合和缺陷的能量是由电子密度-功能-理论(DFT)调查的。通过DF计算Lattice-algebra技术所列举的结构,我们找出了四种不同的多帕浓度的缺陷组合体的最低能量模式。最稳定的结构特点是氧基亚拉特冰层上最近的邻居空位之间令人厌恶的相互作用。所有考虑的二价氧化物的形成内分泌阳性是积极的,并显示出随着三价多巴底体的大小和电密度的下降而减少的趋势。由于小的正成动聚物和与拉多斯内聚物的低氧-连带能量,La $2美元/O3}美元-THO$2}固态溶液的内性比起来相对较高。我们所研究的三价基溶物的结果与那些坚固溶剂比较起来。