Two Kinds of Metastable Structures in an Epitaxial Lanthanum Cobalt Oxide Thin Film
| Autor: | Huaiwen Yang, Richeng Yu, Xiangxiang Guan, Jine Zhang, Yuan Yao, Weipeng Wang, Changzhi Gu, Wei Wang, Q. Q. Lan, Junjie Li, Xi Shen, Jirong Sun, Jing Zhang |
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| Rok vydání: | 2019 |
| Předmět: |
Condensed matter physics
010405 organic chemistry Chemistry chemistry.chemical_element engineering.material 010402 general chemistry 01 natural sciences 0104 chemical sciences Inorganic Chemistry Lattice constant Transmission electron microscopy engineering Lanthanum Brownmillerite Physical and Theoretical Chemistry Thin film Cobalt oxide Superstructure (condensed matter) Perovskite (structure) |
| Zdroj: | Inorganic chemistry. 58(19) |
| ISSN: | 1520-510X |
| Popis: | Thin films have attracted much interest because they often have novel properties different from those of their bulk counterparts. In this work, we tune two metastable states in three kinds of lanthanum cobalt oxide thin films by electron beam irradiation and record their dynamic transition process in situ in a transmission electron microscope. The lanthanum cobalt oxide thin films exhibit a homogeneous microstructure in the initial state and then transfer to a stripelike superstructure with 3a0 periodicity (a0 is the perovskite lattice parameter), further developing into a superstructure with 2a0 periodicity in dark stripes (brownmillerite structure). To explore the inherent energy discrepancy within the two metastable states, we perform first-principles calculations on a LaCoO3-δ (0 ≤ δ ≤ 0.5) thin film system by geometry optimization. The calculation results suggest that the forming energy of the 3a0 periodicity stripelike structure is a little lower than that of the 2a0 periodicity in the LaCoO3-δ thin film. Our work explains why the two stripelike structures coexist in lanthanum cobalt oxide thin films and extends prospective applications related to oxygen vacancies in thin films. |
| Databáze: | OpenAIRE |
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