Preparation of MgO Self-Epitaxial Films for YBCO High-Temperature Coated Conductors

Fei Yu; Yan Xue; Chaowei Zhong; Jiayi Song; Qiong Nie; Xin Hou; Baolei Wang

doi:10.3390/mi14101914

Preparation of MgO Self-Epitaxial Films for YBCO High-Temperature Coated Conductors

Micromachines (Basel). 2023 Oct 8;14(10):1914. doi: 10.3390/mi14101914.

Authors

Fei Yu¹, Yan Xue^{1

2

3}, Chaowei Zhong¹, Jiayi Song¹, Qiong Nie⁴, Xin Hou³, Baolei Wang²

Affiliations

¹ School of Electronic and Communication Engineering, Shenzhen Polytechnic, Shenzhen 518000, China.
² Ningbo Weierskeller Intelligent Technology Co., Ltd., Ningbo 315210, China.
³ Materials Science and Engineering, Tianjin University, Tianjin 300072, China.
⁴ School of Foreign Languages and Trade, Guangzhou City Construction College, Guangzhou 510006, China.

Abstract

Ion beam-assisted deposition (IBAD) has been proposed as a promising texturing technology that uses the film epitaxy method to obtain biaxial texture on a non-textured metal or compound substrate. Magnesium oxide (MgO) is the most well explored texturing material. In order to obtain the optimal biaxial texture, the actual thickness of the IBAD-MgO film must be controlled within 12nm. Due to the bombardment of ion beams, IBAD-MgO has large lattice deformation, poor texture, and many defects in the films. In this work, the solution deposition planarization (SDP) method was used to deposit oxide amorphous Y₂O₃ films on the surface of Hastelloy C276 tapes instead of the electrochemical polishing, sputtering-Al₂O₃ and sputtering-Y₂O₃ in the commercialized buffer layer. An additional homogeneous epitaxy MgO (epi-MgO) layer, which was used to improve the biaxial texture in the IBAD-MgO layer, was deposited on the IBAD-MgO layer by electron-beam evaporation. The effects of growth temperature, film thickness, deposition rate, and oxygen pressure on the texture and morphology of the epi-MgO film were systematically studied. The best full width at half maximum (FWHM) values were 2.2° for the out-of-plane texture and 4.8° for the in-plane texture for epi-MgO films, respectively. Subsequently, the LaMnO₃ cap layer and YBa₂Cu₃O₇-x (YBCO) functional layer were deposited on the epi-MgO layer to test the quality of the MgO layer. Finally, the critical current density of the YBCO films was 6 MA/cm² (77 K, 500 nm, self-field), indicating that this research provides a high-quality MgO substrate for the YBCO layer.

Keywords: fluorene; homogeneous epitaxy; ion beam-assisted deposition; magnesium oxide.

Grants and funding

We gratefully acknowledge the funding from the Basic and Applied Basic Research Funding of Guangdong (No. 2019M650341, No. 2020A1515110551), Provincial Education Department of Guangdong (No. 2021KTSCX277), the National Natural Science Foundation of China (No. 12074264), Provincial High Vocational Education Teaching Reform Research and Practice Project (GDJG2021422), Key funded projects of special funds for scientific and technological innovation strategy of Guangdong Province (pdjh2022a0973, pdjh2022001, pdjh2023a0967) and the Founding of Shenzhen polytechnic (No. 6021310007K, 6022312061K, 6022310034K, 6021271011K, 6021230059K, 6021210078K, LHRC20220402, 1019-8122310001C0, LLJY202306, P-20230703-41376, 7023310168, 7023320062) for this work.