Department of Chemistry and Chemical Engineering, Chalmers University of Technology, SE-412 96 Göteborg, Sweden.
Phys Chem Chem Phys. 2018 May 23;20(20):13697-13704. doi: 10.1039/c7cp07340b.
Acceptor-doped barium zirconates are currently receiving considerable interest because of their high proton conductivity at intermediate temperatures, making them applicable as electrolytes in various electrochemical devices, but the mechanism of proton conduction is unclear. Here, we investigate the role of the acceptor-dopant level in the localized proton motions, i.e. proton transfers between oxygens and O-H reorientations, in hydrated samples of the proton conducting, acceptor-doped, perovskites BaZr1-xInxO3-x/2 with x = 0.10 and 0.20, using quasielastic neutron scattering (QENS). Analysis of the QENS spectra reveals that several proton transfer and O-H reorientational motions contribute to the QENS signal, as a consequence of the locally disordered nature of the structure due to the In doping of these materials, and establishes a generic and complex picture of localized proton dynamics in acceptor-doped barium zirconate based proton conductors. A comparison of the QENS results with vibrational spectroscopy data of the same materials, as reported in the literature, suggests a predominance of O-H reorientational motions in the observed dynamics. The highest doping level corresponds to a more distorted structure and faster dynamics, which thus indicates that some degree of structural disorder is favourable for high local proton mobility.
受主掺杂钡锆酸盐由于其在中温下的高质子电导率而受到广泛关注，使其可作为各种电化学器件的电解质使用，但质子传导的机制尚不清楚。在这里，我们使用准弹性中子散射（QENS）研究了在水合的质子导体、受主掺杂钙钛矿 BaZr1-xInxO3-x/2（其中 x = 0.10 和 0.20）中，受主掺杂剂能级在局部质子运动中的作用，即质子在氧和 O-H 重排之间的转移。对 QENS 光谱的分析表明，由于这些材料的 In 掺杂导致结构局部无序，几种质子转移和 O-H 重排运动对 QENS 信号有贡献，并建立了受主掺杂钡锆酸盐基质子导体中局部质子动力学的通用且复杂的图像。与文献中报道的相同材料的振动光谱数据进行比较，QENS 结果表明 O-H 重排运动在观察到的动力学中占主导地位。最高掺杂水平对应于更扭曲的结构和更快的动力学，这表明一定程度的结构无序有利于局部质子的高迁移率。
