000013614 001__ 13614 000013614 005__ 20241002042305.0 000013614 02470 $$ahttps://doi.org/10.1021/acs.jpcc.4c04098$$2doi 000013614 037__ $$aTEXTUAL 000013614 037__ $$bArticle 000013614 041__ $$aeng 000013614 245__ $$aHydrogen-Induced Topotactic Phase Transformations of Cobaltite Thin Films 000013614 269__ $$a2024-09-30 000013614 336__ $$aArticle 000013614 520__ $$aManipulating physical properties through ion migration in complex oxide thin films is an emerging research direction to achieve tunable materials for advanced applications. While the reduction of complex oxides has been widely reported, few reports exist on the modulation of physical properties through a direct hydrogenation process. Here, we report an unusual mechanism for hydrogen-induced topotactic phase transitions in perovskite La<sub>0.7</sub>Sr<sub>0.3</sub>CoO<sub>3</sub> thin films. Hydrogenation is performed upon annealing in a pure hydrogen gas environment, offering a direct understanding of the role that hydrogen plays at the atomic scale in these transitions. Topotactic phase transformations from the perovskite (P) to hydrogenated-brownmillerite (H-BM) phase can be induced at temperatures as low as 220 °C, while at higher hydrogenation temperatures (320–400 °C), the progression toward more reduced phases is hindered. Density functional theory calculations suggest that hydroxyl bonds are formed with the introduction of hydrogen ions, which lower the formation energy of oxygen vacancies of the neighboring oxygen, enabling the transition from the P to H-BM phase at low temperatures. Furthermore, the impact on the magnetic and electronic properties of the hydrogenation temperature is investigated. Our research provides a potential pathway for utilizing hydrogen as a basis for low-temperature modulation of complex oxide thin films, with potential applications in neuromorphic computing. 000013614 536__ $$oU.S. Department of Energy$$cDE-SC0019273 000013614 536__ $$oAir Force Office of Scientific Research$$cFA9550-22-1-0135 000013614 536__ $$oLawrence Livermore National Lab$$aPostdoctoral Program 000013614 536__ $$oU.S. Department of Energy$$cDE-AC52-07NA27344 000013614 536__ $$oU.S. Department of Energy$$cDE-AC02- 05CH11231 000013614 536__ $$oU.S. Department of Energy$$cDE-SC0012704 000013614 540__ $$a<p>© 2024 The Authors.</p> <p>This publication is licensed under <a href="https://creativecommons.org/licenses/by/4.0/">CC-BY 4.0</a>.</p> 000013614 542__ $$fCC BY 000013614 690__ $$aPritzker School of Molecular Engineering 000013614 7001_ $$1https://orcid.org/0000-0002-2225-6109$$2ORCID$$aFeng, Mingzhen$$uUniversity of California Davis 000013614 7001_ $$aLi, Junjie$$uUniversity of California San Diego 000013614 7001_ $$1https://orcid.org/0000-0001-9907-9967$$2ORCID$$aZhang, Shenli$$uLawrence Livermore National Laboratory 000013614 7001_ $$1https://orcid.org/0000-0002-4653-9197$$2ORCID$$aPofelski, Alexandre$$uBrookhaven National Laboratory 000013614 7001_ $$aEl Hage, Ralph$$uUniversity of California San Diego 000013614 7001_ $$aKlewe, Christoph$$uLawrence Berkeley National Laboratory 000013614 7001_ $$aN'diaye, Alpha T.$$uLawrence Berkeley National Laboratory 000013614 7001_ $$aShafer, Padraic$$uLawrence Berkeley National Laboratory 000013614 7001_ $$1https://orcid.org/0000-0002-1638-7217$$2ORCID$$aZhu, Yimei$$uBrookhaven National Laboratory 000013614 7001_ $$1https://orcid.org/0000-0002-8001-5290$$2ORCID$$aGalli, Giulia$$uUniversity of Chicago 000013614 7001_ $$1https://orcid.org/0000-0002-9078-7120$$2ORCID$$aSchuller, Ivan K.$$uUniversity of California San Diego 000013614 7001_ $$1https://orcid.org/0000-0002-7946-9279$$2ORCID$$aTakamura, Yayoi$$uUniversity of California Davis 000013614 773__ $$tThe Journal of Physical Chemistry C 000013614 8564_ $$yArticle$$9667800b1-e4d2-4d4c-92c1-c1da3e36d1a5$$s3642550$$uhttps://knowledge.uchicago.edu/record/13614/files/feng-et-al-2024-hydrogen-induced-topotactic-phase-transformations-of-cobaltite-thin-films.pdf$$ePublic 000013614 8564_ $$ySupporting information$$9948f3948-a025-4091-a3bc-beaf77a66b00$$s669280$$uhttps://knowledge.uchicago.edu/record/13614/files/jp4c04098_si_001.pdf$$ePublic 000013614 908__ $$aI agree 000013614 909CO $$ooai:uchicago.tind.io:13614$$pGLOBAL_SET 000013614 983__ $$aArticle