Tuning Ionic Conductivity and Stability in Perovskite-Derived Hydrides via Fluorine Substitution
Nur Ika Puji Ayu (a), Naoki Matsui (b), Ryoji Kanno (b), Takashi Kamiyama (c)

(a) Universitas Indonesia
(b) Research Center of All-Solid-State Battery, Institute of Innovation Research, Tokyo Institute
of Technology, Yokohama
(c) Neutron Science Division (KENS), Institute of Materials Structure Science, High Energy
Accelerator Research Organization (KEK), Ibaraki

Abstract

The hydride ion (H-) conducting properties of SrMgH4, which adopts a BaZnF4-type perovskite-derived structure. The hydride ion conductivity of SrMgH4 was demonstrated to be a relatively high value of 5 x 10-5 S cm-1 at 200 oC. Fluorine substitution described as SrMgH4-xFx was also examined to enhance its stability against air. Samples were synthesized via mechanochemical, then the sample purity was verified by X-ray diffraction (XRD). Neutron diffraction (ND) at J-PARC BL09 SPICA was collected to provide structural information. Rietveld analysis using neutron powder diffraction data of SrMgHF3 (x=3) revealed the disordering of fluoride and hydride ions. While fluorine substitution reduced ionic conductivity, SrMgH2F2 and SrMgHF3 show enhanced air stability. These findings demonstrate how controlled anion disorder can optimize the balance between conductivity and stability in hydride-ion-conducting materials.

Keywords: Hydrides, ionic conductor, air stability

Topic: Material Physics