2022年第69回応用物理学会春季学術講演会

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6 薄膜・表面 » 6.4 薄膜新材料

[25a-F307-1~8] 6.4 薄膜新材料

2022年3月25日(金) 09:15 〜 11:30 F307 (F307)

岡 大地(東北大)、高津 浩(京大)

10:00 〜 10:15

[25a-F307-4] Discovery of highly reduced oxide SrCoO2 via electrochemical proton reduction and dehydration

〇Haobo Li1,3、Shunsuke Kobayashi2、Chengchao Zhong3、Morito Namba3、Yu Cao3、Daichi Kato3、Yoshinori Kotani4、Qianmei Lin3、Maokun Wu5、Wei-Hua Wang5、Masaki Kobayashi3、Koji Fujita3、Cedric Tassel3、Takahito Terashima3、Akihide Kuwabara2、Yoji Kobayashi3、Hiroshi Takatsu3、Hiroshi Kageyama3 (1.Osaka Univ. SANKEN、2.JFCC、3.Kyoto Univ.、4.SPring-8、5.Nankai Univ.)

キーワード:strongly correlated oxide, thin film, ionic liquid gating

Controlling oxygen deficiencies is essential for the development of novel chemical and physical properties in strongly correlated oxides. In the recent dedaces, low-temperature topochemical reactions using metal hydrides (e.g., CaH2) are known as a powerful method to lead to highly reduced oxides such as SrFeO2 and LaNiO2 although their applicability is limited due to uncontrollable product. In this work we use a combination of electrochemical protonation and thermal dehydration to synthesize highly reduced oxide. SrCoO2.5 thin film is converted to SrCoO2 by dehydration of HSrCoO2.5 at 350 °C (Figure 1). SrCoO2 represents the first perovskite-derived compound consisting only of tetrahedra, forming a four-legged spin tube. Upon heating, HSrCoO2.5 with distorted octahedra gradually dehydrates (H1-xCoO2.5–x/2) and then switches to the one-dimensional spin tube structure. This suggests that ‘destabilization’ of the SrCoO2.5 precursor by protonation drastically alters the reaction energy landscape. Given that electrochemical protonation has been applied to a variety of transition metal oxides, this simple process opens new avenues for exploring novel oxides.