Promoted Hydride/Oxide Exchange in SrTiO3 by Introduction of Anion Vacancy via Aliovalent Cation Substitution

Fumitaka Takeiri; Kohei Aidzu; Takeshi Yajima; Toshiaki Matsui; Takafumi Yamamoto; Yoji Kobayashi; James Hester; Hiroshi Kageyama

doi:10.1021/acs.inorgchem.7b01845

Promoted Hydride/Oxide Exchange in SrTiO₃ by Introduction of Anion Vacancy via Aliovalent Cation Substitution

Inorg Chem. 2017 Nov 6;56(21):13035-13040. doi: 10.1021/acs.inorgchem.7b01845.

Authors

Fumitaka Takeiri¹, Kohei Aidzu¹, Takeshi Yajima², Toshiaki Matsui¹, Takafumi Yamamoto¹, Yoji Kobayashi¹, James Hester³, Hiroshi Kageyama^{1

4}

Affiliations

¹ Department of Energy and Hydrocarbon Chemistry, Graduate School of Engineering, Kyoto University , Nishikyo-ku, Kyoto 615-8510, Japan.
² Institute for Solid State Physics, The University of Tokyo , Kashiwa, Chiba 277-8581, Japan.
³ Australian Centre for Neutron Scattering, Australian Nuclear Science and Technology Organisation , Locked Bag 2001, Kirrawee DC, NSW 2232, Australia.
⁴ CREST, Japan Science and Technology Agency , 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.

PMID: 29068668
DOI: 10.1021/acs.inorgchem.7b01845

Abstract

We investigated topochemical anion exchange reactions for a Sc^III-substituted SrTi^IVO₃ perovskite, Sr(Ti_1-ySc_y)O_3-y/2□_y/2 (y ≤ 0.1), using CaH₂. It was found that the initial introduction of a small amount of anion vacancies (y/2) is crucial to enhance the anion (H^-/O^2-) exchangeability. For example, hydride reduction of Sr(Ti_0.95Sc_0.05)O_2.975 yielded the oxyhydride SrTi_0.95Sc_0.05O_2.56H_0.41 in which the hydride concentration is increased by 33% with respect to pristine SrTiO₃ (leading to SrTiO_2.76H_0.24). This observation highlights the importance of anion vacancies to improve anion (H^-/O^2-) diffusion, which is a well-known strategy for improving oxide anion conductivity, and suggests that such a vacancy-assisted reaction could be applied to other anion exchange reactions (e.g., F^-/O^2- and N^3-/O^2-) to extend the solubility range.