Spontaneous phase segregation of Sr2NiO3 and SrNi2O3 during SrNiO3 heteroepitaxy

Le Wang; Zhenzhong Yang; Xinmao Yin; Sandra D Taylor; Xu He; Chi Sin Tang; Mark E Bowden; Jiali Zhao; Jiaou Wang; Jishan Liu; Daniel E Perea; Linda Wangoh; Andrew T S Wee; Hua Zhou; Scott A Chambers; Yingge Du

doi:10.1126/sciadv.abe2866

Spontaneous phase segregation of Sr₂NiO₃ and SrNi₂O₃ during SrNiO₃ heteroepitaxy

Sci Adv. 2021 Mar 5;7(10):eabe2866. doi: 10.1126/sciadv.abe2866. Print 2021 Mar.

Authors

Le Wang¹, Zhenzhong Yang¹, Xinmao Yin², Sandra D Taylor¹, Xu He³, Chi Sin Tang⁴, Mark E Bowden⁵, Jiali Zhao⁶, Jiaou Wang⁶, Jishan Liu^{1

7}, Daniel E Perea⁸, Linda Wangoh¹, Andrew T S Wee², Hua Zhou⁹, Scott A Chambers¹⁰, Yingge Du¹⁰

Affiliations

¹ Physical and Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland, WA 99354, USA.
² Department of Physics, Faculty of Science, National University of Singapore, Singapore 117542, Singapore.
³ Catalan Institute of Nanoscience and Nanotechnology-ICN2, CSIC and BIST, Campus UAB, 08193 Bellaterra, Spain.
⁴ NUS Graduate School for Integrative Sciences and Engineering, National University of Singapore, Singapore 117456, Singapore.
⁵ Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, WA 99354, USA.
⁶ Beijing Synchrotron Radiation Facility, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100039, China.
⁷ State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences (CAS) , Shanghai 200050, China.
⁸ Earth and Biological Sciences Directorate, Pacific Northwest National Laboratory, Richland, WA 99354, USA.
⁹ X-ray Science Division, Advanced Photon Source, Argonne National Laboratory, Lemont, IL 60439, USA.
¹⁰ Physical and Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland, WA 99354, USA. sa.chambers@pnnl.gov yingge.du@pnnl.gov.

Abstract

Recent discovery of superconductivity in Nd_0.8Sr_0.2NiO₂ motivates the synthesis of other nickelates for providing insights into the origin of high-temperature superconductivity. However, the synthesis of stoichiometric R _1-x Sr _x NiO₃ thin films over a range of x has proven challenging. Moreover, little is known about the structures and properties of the end member SrNiO₃ Here, we show that spontaneous phase segregation occurs while depositing SrNiO₃ thin films on perovskite oxide substrates by molecular beam epitaxy. Two coexisting oxygen-deficient Ruddlesden-Popper phases, Sr₂NiO₃ and SrNi₂O₃, are formed to balance the stoichiometry and stabilize the energetically preferred Ni²⁺ cation. Our study sheds light on an unusual oxide thin-film nucleation process driven by the instability in perovskite structured SrNiO₃ and the tendency of transition metal cations to form their most stable valence (i.e., Ni²⁺ in this case). The resulting metastable reduced Ruddlesden-Popper structures offer a testbed for further studying emerging phenomena in nickel-based oxides.

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