Study on the Effects of Oxygen Vacancy in SrCoOx Thin Films

作者: 史志界 * , 江正华 , 周 浩 , 汤如俊 :苏州大学物理与光电•能源学部,江苏省薄膜材料重点实验室,江苏 苏州;

关键词: SrCoOx退火温度氧空位SrCoOx Annealing Temperature Oxygen Vacancy

本文中我们采用脉冲激光沉积技术在SrTiO3(001)基底上制备出钙铁石结构的SrCoO2.5(BM-SCO)外延薄膜,在氧气氛围、不同温度下对样品进行后退火工艺处理,使薄膜发生由钙铁石相到钙钛矿相(P-SCO)的拓扑相变。研究结果表明薄膜的磁性和微结构在相变温度(250℃)附近发生很大的变化。当退火温度为250℃ ≤ T < 600℃时,薄膜由BM-SCO转变为BM-SCO与P-SCO的共存相(Mix-SCO),薄膜的磁性明显增强,由反铁磁性转变为铁磁性(Tc~180 K)。当退火温度达到600℃时,完全转变为钙钛矿型SrCoO3–δ。XPS拟合结果显示,退火后Co的价态发生变化,从Co3+转变为Co4+,即薄膜中的部分氧空位被填充。故退火后钙钛矿型SrCoO3–δ的氧含量(3–δ)约为2.75。

Abstract: In this work, we grew brownmillerite SrCoO2.5 (BM-SCO) epitaxial thin films on (001) SrTiO3 substrates by pulsed laser deposition and performed post-annealing at various temperatures in oxygen atmosphere for topotactic conversion into the perovskite phase (P-SCO). The results show that the magnetic properties and microstructure of the films have a great change near the critical temperature (250˚C). When a BM-SCO film was annealed in lower temperature (250˚C ≤ T < 600˚C), a mixed-phase of BM-SCO and P-SCO (Mix-SCO) was observed, and oxygen intercalation drove the antiferromagnetic phase to ferromagnetic phase (Tc~180 K). We also found that in post-annealing under 600˚C a complete phase transition from the brownmillerite SrCoO2.5 to the perovskite SrCoO3–δ was exhibited. XPS fitting results clearly indicate a change in the Co valence state from 3+ toward 4+. So some oxygen vacancies in the films are filled. Therefore, we conclude that the oxygen concentration (3–δ) in perovskite SrCoO3–δ by post-annealing is about 2.75.

文章引用: 史志界 , 江正华 , 周 浩 , 汤如俊 (2016) SrCoOx薄膜中的氧空位效应研究。 应用物理, 6, 205-211. doi: 10.12677/APP.2016.610026


[1] Suntivich, J., May, K.J., Gasteiger, H.A., Goodenough, J.B. and Shao-Horn, Y. (2013) A Perovskite Oxide Optimized for Oxygen Evolution Catalysis from Molecular Orbital Principles. Science, 334, 1383-1385.

[2] Jeen, H., Choi, W.S., Freeland, J.W., Ohta, H., Jung, C.U. and Lee, H.N. (2013) Topotactic Phase Transformation of the Brownmillerite SrCoO2.5 to the Perovskite SrCoO3–δ. Advanced Materials, 25, 3651-3656.

[3] Meyer, T.L., Jeen, H., Gao, X., Petrie, J.R., Chisholm, M.F. and Lee, H.Y. (2016) Symmetry-Driven Atomic Rearrangement at a Brownmillerite-Perovskite Interface. Advanced Electronic Materials, 2, 1500201.

[4] Mefford, J.T., Rong, X., Abakumov, A.M., Hardin, W.G., Dai, S., Kolpak, A.M., Johnston, K.P. and Stevenson, K.J. (2015) Water Electrolysis on La1-xSrxCoO3–δ Perovskite Electrocatalysts. Nature Communications, 7, Article Number: 11053.

[5] Petrie, J.R., Jeen, H., Barron, S.C., Meyer, T.L. and Lee, H.N. (2016) Enhancing Perovskite Electrocatalysis through Strain Tuning of the Oxygen Deficiency. Journal of the American Chemical Society, 138, 7252-7255.

[6] Choi, W.S., Jeen, H., Lee, J.H., Ambrose Seo, S.S., Cooper, V.R., Rabe, K.M. and Lee, H.N. (2013) Reversal of the Lattice Structure in SrCoOx Epitaxial Thin Films Studied by Real-Time Optical Spectroscopy and First-Principles Calculations. Physical Review Letters, 111, 097401.

[7] Lee, J.H. and Rabe, K.M. (2011) Coupled Magnetic-Ferroelectric Metal-Insulator Transition in Epitaxially Strained SrCoO3 from First Principles. Physical Review Letters, 107, 067601.

[8] Calle-Vallejo, F., Díaz-Morales, O.A., Kolb, M.J. and Koper, M.T.M. (2015) Why Is Bulk Thermochemistry a Good Descriptor for the Electrocatalytic Activity of Transition Metal Oxides? ACS Catalysis, 5, 869-873.

[9] Jeen, H., Bi, Z.H., Choi, W.S., Chisholm, M.F., Bridges, C.A., Paranthaman, M.P. and Lee, H.N. (2013) Orienting Oxygen Vacancies for Fast Catalytic Reaction. Advanced Materials, 25, 6459-6463.

[10] Xie, C.K., Nie, Y.F., Wells, B.O. Budnick, J.I. Hines, W.A. and Dabrowski, B. (2011) Magnetic Phase Separation in SrCoOx (2.5 ≤ x ≤ 3). Applied Physics Letters, 99, 052503.

[11] Rueckert, F.J., Nie, Y.F., Abughayada, C., Sabok-Sayr, S.A., Mohottala, H.E., Budnick, J.I., Hines, W.A., Dabrowski, B. and Wells, B.O. (2013) Suppression of Magnetic Phase Separation in Epitaxial SrCoOx Films. Applied Physics Letters, 102, 152402.

[12] Ichikawa, N., Iwanowska, M., Kawai, M., Calers, C., Paulusb, W. and Shimakawa, Y. (2012) Reduction and Oxidation of SrCoO2.5 Thin Films at Low Temperatures. Dalton Transactions, 41, 10507.

[13] Jeen, H., Choi, W.S., Biegalski, M.D., Folkman, C.M., Tung, I.-C., Fong, D.D., Freeland, J.W., Shin, D., Ohta, H., Chisholm, M.F. and Lee, H.N. (2013) Reversible Redox Reactions in an Epitaxially Stabilized SrCoOx Oxygen Sponge. Nature Materials, 12, 1057.

[14] Choi, W.S., Jeen, H., Lee, J.H., Ambrose Seo, S.S., Cooper, V.R., Rabe, K.M. and Lee, H.N. (2013)Reversal of the Lattice Structure in SrCoOx Epitaxial Thin Films Studied by Real-Time Optical Spectroscopy and First-Principles Calculations. Physical Review Letters, 111, 097401.

[15] Jeen, H. and Lee, H.N. (2015) Structural Evolution of Epitaxial SrCoOx Films near Topotactic Phase Transition. AIP Advances, 5, 127123.

[16] Hu, S., Yue, Z., Lim, J.S., Callori, S.J., Bertinshaw, J., Ikeda-Ohno, A., Ohkochi, T., Yang, C.-H., Wang, X., Ulrich, C. and Seidel, J. (2015) Growth and Properties of Fully Strained SrCoOx (x≈ 2.8) Thin Films on DyScO3. Advanced Materials Interfaces, 2, 1500012.

[17] Petrie, J.R., Mitra, C., Jeen, H., Choi, W.S., Meyer, T.L., Reboredo, F.A., Freeland, J.W., Eres, G. and Lee, H.N. (2016) Strain control of oxygen vacancies in epitaxial strontium cobaltite films. Advanced Functional Materials, 26, 1564- 1570.

[18] 张利文, 张胤, 刘铃声, 王 强, 张国芳. 钙钛矿氧化物 Eu1-xSrx CoO3-δ的结构和性能.稀土, 2010, 31(4): 7-11.

[19] Hong, W.T., Stoerzinger, K.A., Crumlin, E.J., Mutoro, E., Jeen, H., Lee, H.N. and Shao-Horn, Y. (2016) Near-Am- bient Pressure XPS of High-Temperature Surface Chemistry in Sr2Co2O5 Thin Films. Topics in Catalysis, 59, 574-558.

[20] 顾经伟, 史志界. 后退火对外延 Eu0.5Ba0.5TiO3薄膜表面形貌的影响. 应用物理, 2015, 5(12): 165-171.