[18p-Z15-1~15] 6.4 Thin films and New materials

▼ [18p-Z15-10] Electrochemical Redox reaction of SrCoO_2.5 films using YSZ oxide ion conductor

〇(D)Qian Yang¹, Joonhyuk Lee², Hyoungjeen Jeen², Jiake Wei³, Bin Feng⁴, Yuichi Ikuhara^3,4, Hai Jun Cho^1,5, Hiromichi Ohta^1,5 (1.IST-Hokkaido U., 2.Pusan Nat'l Univ., 3.Kyoto Univ., 4.Univ. Tokyo, 5.RIES-Hokkaido Univ.)

Keywords:oxide ion conductor YSZ, SrCoO2

SrCoO_x shows kinds of properties depending on the oxygen content x; Brownmillerite (BM) SrCoO_2.5 (Co³⁺) is brown colored antiferromagnetic insulator and perovskite (PV) SrCoO_3−δ (Co⁴⁺) is black colored ferromagnetic metal. Protonated BM HSrCoO_2.5 (Co²⁺) is colorless transparent weak ferromagnetic insulator. There is no report on the reduced SrCoO₂ (Co²⁺). In order to obtain SrCoO₂ and clarify the properties, we used an oxide ion conductor YSZ as the solid electrolyte. Here we report first observation of SrCoO₂ by utilizing YSZ as the solid electrolyte. Simultaneously, the valence state of Co ion could be regulated from Co²⁺ to Co⁴⁺ accompanying the optical, electrical properties transition. These observations will be useful to develop a functional device utilizing the electrochemical redox reaction of SrCoOx.