Protonation-Induced B-Site Deficiency in Perovskite-Type Oxides: Fully Hydrated BaSc0.67O(OH)2 as a Proton Conductor
Protonation-Induced B-Site Deficiency in Perovskite-Type Oxides: Fully Hydrated BaSc0.67O(OH)2 as a Proton Conductor
复制标题
DOI：
10.1021/acs.chemmater.1c01017
复制
发表时间：
2021-07-28
影响因子：
8.6
通讯作者：
Takamura, Hitoshi
中科院分区：
文献类型：
--
作者：
Kawamori, Hiroaki;Oikawa, Itaru;Takamura, Hitoshi
设计高质子导电性钙钛矿型氧化物的概念之一是提高质子浓度。在这项研究中，我们关注的是Ba-Sc氧化物，它以其褐铁矿型结构和高质子浓度的巨大潜力而闻名。为获得高水合相，以氢氧化物为水源进行了高压合成。虽然期望钙钛矿型BaScO2（OH）只是水合相，但Sc空位的形成增加了，导致Ba-Sc氧化物的水合作用更大。充分水合相可能为钙钛矿型BaSc0.67O(OH)(2)。三分之一的Sc位是空的，Sc空位的有效电荷由多余的质子补偿。第一性原理计算表明，Sc空位中的质子取向于Sc空位，并以类似于氢石榴石取代的方式补偿b位电荷。广泛水化条件导致的b位缺乏是钙钛矿型质子导体质子浓度增加的新机制。电导率，10(-2)S。在450 ~ 500℃时，电导率与掺杂BaZrO3的电导率相当，尽管在脱水温度下电导率发生了不连续的变化。
One of the concepts for the design of a highly proton-conductive perovskite-type oxide is to increase the proton concentration. In this study, we focused on Ba-Sc oxide known for its brownmillerite-type structure and great potential for a high proton concentration. To achieve the highly hydrated phase, high-pressure synthesis was conducted using hydroxide as the H2O source. Although the expectation was that perovskite-type BaScO2(OH) would simply be a hydrated phase, the formation of Sc vacancies increased resulting in the greater hydration of the Ba-Sc oxide. It was likely that the fully hydrated phase was perovskite-type BaSc0.67O(OH)(2). One third of the Sc sites were vacant, and the effective charge of Sc vacancies were compensated by the excess protons. First principles calculation revealed that the protons residing in the Sc vacancies were orientated toward a Sc vacancy and compensated the B-site charge in a manner similar to that of hydrogarnet substitution. This B-site deficiency caused by the extensive hydration condition is a novel mechanism to increase the proton concentration of perovskite-type proton conductors. The electrical conductivity, 10(-2 )S.cm(-1) at 450-500 degrees C, was comparable to that of acceptor-doped BaZrO3, although the conductivity discontinuously changed at dehydration temperature.