温度控制织构金属基带上YBCO外延薄膜生长及缺陷研究

doi:10.3724/SP.J.1077.2013.12385

摘要/Abstract

摘要：

采用直流溅射法在Y₂O₃/YSZ/CeO₂(YYC)缓冲层的织构NiW基带上, 通过基片温度调制YBa₂Cu₃O_7-δ(YBCO)外延薄膜生长。X射线衍射仪(XRD)表征显示, 基片温度强烈地影响YBCO薄膜的外延生长: 在较低的基片温度下薄膜趋于a轴取向生长, 随基片温度升高薄膜逐渐变为纯c轴取向生长。由于a轴晶粒引起的大角度晶界会阻碍超导电流在a-b面内的传输, 因此YBCO薄膜的微观结构和超导电性能随温度升高而得到改善, 但是随着基片温度继续升高, 基带的氧化程度加剧, YBCO与缓冲层间发生界面反应, 从而导致薄膜质量衰退。本

关键词: YBa₂Cu₃O_7-δ, (YBCO), 基片温度, 生长取向, 位错密度

Abstract:

Epitaxial YBa₂Cu₃O_7-_δ(YBCO) thin films were grown on Y₂O₃/YSZ/CeO₂ (YYC) buffered Ni-5at%W substrates by direct-current sputtering, and induced by substrate temperature. X-ray diffraction (XRD) results showed that the substrate temperature strongly influenced the epitaxial growth of YBCO films: the a-axis preferential grains grew at lower substrate temperature, and strictly c-axis epitaxial YBCO films were achieved at higher substrate temperature. The amount of a-axis YBCO component evaluated from the ratio of XRD χ-scan integrated intensity of the a-axis and c-axis for the YBCO (102) plane decreased as the substrate temperature increased. Since the development of the a-axis component can result in high angle grain boundaries, which can degrade the I_c passing through the a-b plane, the microstructure and the critical current density of YBCO thin films were improved as substrate temperature increasing. While the microstructure and the critical current density of YBCO thin films were deteriorated above 780℃ for the baseband oxidation and the interface reaction between the YBCO and the buffer layer. The dislocation density in the YBCO thin films was measured and calculated. The relationship between the dislocation density and critical current density (J_c) was systematically investigated, J_c was much more sensitive to the screw dislocation than to the edge dislocation, which was attributed to the spiral growth mechanism of YBCO thin films.

Key words: YBa₂Cu₃O_7-&#x003b4, (YBCO), substrate temperature, crystal orientation, dislocation density

中图分类号:

TM26

徐亚新, 熊杰, 夏钰东, 张飞, 薛炎, 陶伯万. 温度控制织构金属基带上YBCO外延薄膜生长及缺陷研究[J]. 无机材料学报, 2013, 28(5): 491-496.

XU Ya-Xin, XIONG Jie, XIA Yu-Dong, ZHANG Fei, XUE Yan, TAO Bo-Wan. [J]. Journal of Inorganic Materials, 2013, 28(5): 491-496.

图/表 7

图1 不同基片温度下制备的YBCO薄膜的XRD图谱

Fig. 1 XRD patterns of YBCO films prepared at different substrate temperatures

图2 不同基片温度下制备的YBCO样品(102)面χ扫描图谱

Fig. 2 (102) plane χ scan of YBCO films prepared at different substrate temperatures

图3 基片温度为760℃时制备的YBCO薄膜的SEM照片

Fig. 3 SEM image of the YBCO thin film prepared at substrate temperature of 760℃

Table 1 FWHMs, tilt angle αω, density of the screw type threading dislocations NS, density of edge dislocations NE and the total dislocation density of YBCO thin films prepared at different substrate temperatures

	740℃	760℃	780℃	800℃	820℃	sinθ/λ
Δω(002)	1.625	3.222	2.146	4.956	2.984	0.0855
Δω(004)	1.442	2.231	2.005	2.963	1.762	0.171
Δω(005)	1.439	2.046	2.193	2.353	1.780	0.21375
Δω(007)	1.492	1.843	1.970	1.976	1.638	0.29925
Δω(008)	1.337	1.652	2.046	1.875	1.042	0.342
α_ω	0.02366	0.02055	0.03453	0.01422	0.01121	-
N_S	4.79×10¹⁰	3.61×10¹⁰	1.02×10¹¹	1.73×10¹⁰	1.07×10¹⁰	-
ΔΦ(103)	4.862	5.618	5.325	5.385	4.426	-
N_E	1.63×10¹²	2.17×10¹²	1.95×10¹²	2.00×10¹²	1.35×10¹²	-
N	1.68×10¹²	2.21×10¹²	2.05×10¹²	2.01×10¹²	1.36×10¹²	-

图4 不同基片温度下制备的YBCO薄膜的Williamson-Hall图谱

Fig. 4 Williamson-Hall patterns of YBCO films prepared at different substrate temperatures

图5 不同基片温度制备的YBCO薄膜的临界电流密度Jc(77 K, 0 T)、螺位错密度NS、刃型位错密度NE和总位错密度N

Fig. 5 The critical current density Jc(77K,0T), the density of the screw type threading dislocations (NS), the edge dislocations(NE) and the total dislocations(N) of YBCO thin films prepared at different substrate temperatures

图6 临界电流密度(Jc)与(a)螺位错密度(NS)及(b)刃型位错密度(NE)关系曲线

Fig. 6 The relationship between the critical current density (Jc) and the dislocations density: (a) screw type threading dislocations NS; (b) edge dislocations NE

参考文献 11

[1]	Larbalestier David, Gurevich Alex, Feldmann Matthew D, et al. High-Tc superconducting materials for electric power applications. Nature, 2001, 414(11): 368-377.
[2]	陶伯万, 熊杰, 李言荣, 等. YBCO超导带材研究进展. 中国材料进展, 2009, 28(4): 16-22.
[3]	古宏伟, 杨坚, 刘慧舟, 等. YBa2Cu3O7-x涂层导体的研究进展. 中国稀土学报, 2006, 24(3): 258-268.
[4]	蔡传兵, 刘志勇, 鲁玉明. 实用超导材料的发展演变及其前景展望. 中国材料进展, 2011, 30(3): 1-8.
[5]	Wang J, Kwon J H, Yoon J, et al. Flux pinning in YBa2Cu3O7-δ thin film samples linked to stacking fault density. Applied Physics Letters, 2008, 92(8): 082507-1-3.
[6]	Specht E D, Goyal A, Li J, et al. Stacking faults in YBa2Cu3O7-x: Measurement using X-ray diffraction and effects on critical current. Applied Physics Letters, 2006, 89(16): 162510-1-3.
[7]	粟飙, 王又青, 王秋良, 等. 超导薄膜螺旋生长结构对临界电流密度的影响. 低温物理学报, 1998, 20(2): 114-118.
[8]	Xiong J, Tao B W, Li Y R, et al. Reel-to-reel continuous simultaneous double-sided deposition of highly textured CeO2 templates for YBa2Cu3O7-δ coated conductors. Superconductor Science and Technology, 2008, 21(2): 025016-1-5.
[9]	Xiong J, Qin W F, Li Y R, et al. High-resolution XRD study of stress-modulated YBCO films with various thicknesses. Journal of Crystal Growth, 2007, 300(2): 364-367.
[10]	Shi D Q, Ko R K, Song K J, et al. Effects of deposition rate and thickness on the properties of YBCO films deposited by pulsed laser deposition. Superconductor Science and Technology, 2004, 17(2): S42-S45.
[11]	Williamson G K, Hall W H. X-ray line broadening from field aluminium and wolfram. Acta Metallurgica, 1953, 1(1): 22-31.