Phase transformation of the brownmillerite SrCoO2.5 thin film through alkaline water electrolysis

• Published in: Journal of the Korean Physical Society Vol. 64; no. 12; pp. 1845 - 1848
• Main Authors: Tambunan, Octolia Togibasa, Lee, Min Young, Kim, Deok Hyeon, Parwanta, Kadek Juliana, Jung, Chang Uk
• Format: Journal Article
• Language: English
• Published: Seoul The Korean Physical Society 01.06.2014; 한국물리학회
• Subjects: Mathematical and Computational Physics; Particle and Nuclear Physics; Physics; Physics and Astronomy; Theoretical; 물리학; Phase transformation; Water electrolysis; Brownmillerite SrCoO; Thin film
• ISSN: 0374-4884; 1976-8524
• DOI: 10.3938/jkps.64.1845

A phase transformation from insulating brownmillerite SrCoO 2.5 to conducting perovskite SrCoO 3 through electrochemical oxidation has been demonstrated for thin films of SrCoOx on a SrTiO 3 (001) substrate. The cobalt-oxide film strongly favors the brownmillerite phase of SrCoO 2.5 instead of the perovskite phase of SrCoO 3 on a SrTiO 3 (001) substrate due to its low lattice mismatch. Therefore, the phase transformation has its own retention. The alkaline water electrolysis occurs between the copper cathode and the SrCoO 2.5 film anode. The H + ions are attracted to the cathode and generate H 2 gas. The OH − ions are attracted to the film’s surface and generate a rich amount of oxygen to fill the oxygen vacancy channel of brownmillerite SrCoO 2.5 . The phase transformation was verified from the change in the out-of-plane lattice constant and the change in the resistivity of the electrolyzed film.