本研究以厚膜晶種成長大尺寸YBCO單晶粒，並Y211層作緩衝層提高接種成功率。其中晶體成長生胚之尺寸包括25mm、30mm、40mm以及50mm等樣品，除了探討主晶粒成長尺寸、次晶粒成核數等表面形貌，更包含生胚壓製技術、生胚密度分析、單晶粒塊材超導性質量測等，最後更嘗試將使用過後之晶種進行再利用接種實驗。
厚晶種容易遭熔融液相破壞，使得MgO基板成為異質成核點，使接種四面(001)晶面成功率低約20%，而YBCO超導性質有強烈的異向性，高角度晶界將使得超導電流無法通過，性質降低。本文首先提出Y211緩衝層應用置入技術，已大幅提高接種成功率至100%，並加以探討影響成核原因。此外，整合不同降溫曲線(單段、兩段、三段式降溫)於40mm大小的生胚，探討溫度曲線對晶粒成長面積及機制之影響，其中以兩段式降溫可得到最大單晶粒面積(~732mm2)，於液態氮(77K)之擄磁強度可達到1840高斯。
於TSMG製程中使用之生胚尺寸限制了晶粒成長的極限，而大尺寸生胚於壓製過程中會有應力分配不均之現象，於脫膜時容易產生龜裂，甚至坯體完全崩裂。本文特添加溶劑於生胚前驅物，以增加壓胚過程中粉體之流動性，輔助成型50mm大尺寸生胚，且不影響單晶粒成長製程。於密度分析部分，隨著生胚尺寸上升時生胚密度會下降，且適量的溶劑可有效提升坯體密度。
過去以厚膜晶種接種超導體單晶粒之製程後，晶種不可再重複使用。本文使用緩衝層技術，可預防晶種在製程後剝落，得以再利用厚膜晶種，且最高重複使用至三次。隨再利用次數越多，接種所成長的單晶粒面積漸減，但部份樣品呈現擄磁性值上升之現象，於22mm塊材擄磁強度可達到1755高斯。

YBCO single grain can be obtained by the TSMG process, which avoids forming the high Angle boundary. Based on Bean Model ,the property of superconductor increases with grain size, implied that the large single grain fabrication should be developed There are three factors affect the grain size, including seeds selection ,the thermal profile ,and a pellet size.
A film seed has superheating effect, which shows the higher thermal stability. However, the success seeding radio of the thin film in the TSMG process is only about 20%. With inserting a small size Y211 buffer layer between the seed and pellet, the success ratio of seeding is increased to 100%. Besides, this study also reports influence of the different thermal profile setting (one-stage, two-stage, and three-stage) on the 40mm pellets. The largest YBCO single domain is reached, with a two-stage cooling curve. Moreover, with a buffer layer insert, the NdBCO thick films can avoid peeling off, implied that a thick film seed can be reused at least three times, and the single grain dimension decreases with the times of reuse.
This study also develops a possible method of the low pressure compressing process for a large pellet (50mm) by adding the lubricant. From the density analysis, the density of a pellet decrease with the pellet size increasing. An appropriate concentration of the lubricant addition can increase the pellet density effectively without affecting the grain growth process.

1 J. G. Bednorz and K. A. Muller, “Possible High Tc Superconductivity in the Ba-La-Cu-O system.” Z. Phys. B, 64, 189 (1986)
2 M. K. Wu, J. R. Ashburn, C. J. Torng, P. H. Hor, R.L. Meng, L. Gao, Z. J. Huang, Y. Q. Wang and C. W. Chu, “Superconductivity at 93 K in a new mixed-phase Y-Ba-Cu-O compound system at ambient pressure.” Phys. Rev. Lett., 58, 908 (1987)
3 J. Nagamatsu, N. Nakagawa, T. Muranaka, Y. Zenitani and J. Akimitsu, “Superconductivity at 39K in magnesium diboride.” Nature 410, 63-64 (2001).
4 K. Shimizu, H. Ishikawa, D. Takao, T. Yagi and K. Amaya. “Superconductivity in compressed lithium at 20 K.” Nature 419, 597 - 599 (2002).
5 M. Cyrot and D. Pavuna, “Introduction to Superconductivity and High-Tc Materials.” World Scientific, (1992)
6 JCPDS-ICDD, PDF-number：86-0472.
7 T. Hatano, A. Matsushita, K. Nakamura, Y. Sakka, T. Matsumoto and K. Ogawa, “Superconducting and Transport Properties of B-Y-Cu-O Compounds –Orthorhombic and Tetragonal Phases.” Jpn. J. Appl. Phys. 26, L721 (1987).
8 Y. Shiohara and A. Endo, “Crystal growth of bulk high-Tc superconducting oxide materials.” Mat. Sci. Eng. 1-2, R19 (1997).
9 T. B. Lindemer, J. F. Hunley, J. E. Gates, Jr., A. L. Sutton, J. Brynestad, C. R. Hubbard and P. K. Gallagher, “Experimental and Thermodynamic Study of Nonstoichiometry in 〈YBa2Cu3O7-x〉.” J. Am. Ceram. Soc. 72, 1775 (1989).
10 B. J. Lee and D. N. Lee, “Thermodynamic Evaluation for the Y2O3–BaO–CuOx System.” J. Am. Ceram. Soc. 74, 78 (1991).
11 R. J. Cava, B. Batlogg, C. H. Chen, E. A. Rietman, S. M. Zahurak and D. Werder, “Oxygen stoichiometry, superconductivity and normal-state properties of YBa2Cu3O7–δ.” Nature 329, 423 (1987).
12 M. Kambara, T. Umeda, M. Tagami, X. Yao, E. A. Goodlin and Y. Shiohara, “Construction of the Quasi-ternary Phase Diagram in the NdO1.5BaO-CuOx system in an air atmosphere. Pt.1. equilibrium tie lines in the Nd1+xBa2-xCu3O6+ delta solid solution and liquid region” J. Am. Ceram. Soc. 81, 2116 (1998).
13 S. Jin, T.H. Tiefel, R.C. Sherwood, M.E. Davis, R.B. van Dover, G.W. Kammlott, R.A. Fastnacht and H.D. Keith,” High critical currents in Y‐Ba‐Cu‐O superconductors.” Appl. Phys.Lett. 52 2074 (1988).
14 金重勳編, ”磁性技術手冊,”中華民國磁性技術協會出版,民國九十一年七月
15 K. Salama, B. Selvamanickam, L. Gao and K. Sun, “High current density in bulk YBa2Cu3Ox superconductor.” Appl. Phys. Lett.54, 2352 (1989).
16 H. Hojaji, K.A. Michael, A. Barkatt, A.N. Thorpe, F.W. Matthew, I.G. Talmy, D.A. Haught and S. Alterescu, “A comparative study of sintered and melt-grown recrystallized YBa2Cu3Ox.” J. Mater. Res. 4 28 (1989).
17 C. Varanasi and P.J. McGinn, “Effect of YBa2Cu3O7−x grain size on the nucleation of Y2BaCuO5 during melt texturing.” Mater. Lett. 17, 205 (1993).
18 M. Murakami, M. Morita, K. Doi, and M. Miyamoto, “A New Process with the Promise of High Jc in Oxide Superconductors.” Jpn. J. Appl. Phys. Part 228, 1189 (1989).
19 H. Fujimoto, M. Murakami, S. Gotoh, N. Koshizuka and S. Tanaka, “Advances in Superconductivity Ⅱ”Symp. Superconductivity 89,285 (1990).
20 Z. Lian, Z. Pingxian, J. Ping, W. Keguang, W. Jingrong and W. Xiaozu, “The properties of YBCO superconductors prepared by a new approach: the powder melting process” Supercond. Sci. Technol. 3, 490 (1990).
21 Z. Lian, Z. Pingxian, J. Ping, W. Keguang, W. Jingrong and W. Xiaozu, “High Jc YBCO superconductors Prepared by the “Powder Melting Process” IEEE Trans. Mag. 27, 912 (1991).
22 M. Morita, S. Takebayashi, M. Tanaka and K. Kimura, “Quench and melt growth (QMG) process for large bulk superconductor fabrication“ Advanced Superconductors 3, 733 (1991).
23 K. Sawano, M. Morita, M. Tanaka, T. Sasaki, K. Kimura, S. Takebayashi, M. Kimura and K. Miyamoto, “High magnetic flux trapping by melt-grown YBaCuO superconductors.” Jpn. J. Appl. Phys. 30, L1157 (1991).
24 X. Chaud, D. Isfort, E. Beaugnon and R. tournier, “Isothermal growth of large YBa2Cu3O7-x single domains up to 93mm.” Physica C 341-348, 2413-2416 (2000).
25 T. Izumi and Y. Shiohara, “Growth mechanism of YBa2Cu3Oy superconductors prepared by the horizontal Bridgeman method.” J. Mat. Res. 7, 16 (1992).
26 M. Murakami, “Melt Processed High-Temperature Superconductors.” World Scientific, (1992).
27 R. J. Cava, B. Batlogg, C. H. Chen, E. A. Rietman, S. M. Zahurak and D. Werder, “Oxygen stoichiometry, superconductivity and normal-state properties of YBa2Cu3O7–δ.” Nature 329, 423 (1987).
28 H. Fujimoto, C. Cai and E. Ohtabara, “Sm–Ba–Cu–O bulk superconductors melt-processed in air.” Physica C 372-376, 1111 (2002).
29 S. H. Hsu, I. G. Chen and M. K. Wu, “Preparation of c-oriented Nd-Ba-Cu-O/Ag melt-growth sample in air” Supercond. Sci. Technol. 15, 653-659 (2002).
30 S. I. Yoo, N. Sakai, H. Kojo, S. Takebayashi, N. Hayashi, M. Takahashi, K. Sawada, T. Higuchi and M. Murakami, “Progress in melt processing of Nd-Ba-Cu-O superconductors” IEEE Trans. Appl. Supercond. 7 , No. 2 (1997).
31 C. Cai, K. Tachibana and H. Fujimoti, “Study on single-domain growth of Y1.8Ba2.4Cu3.4Oy/Ag system by using Nd123/MgO thin film as seed.” Supercond. Sci. Technol. 13, 698 (2000).
32 C. Cai and H. Fujimoto, “Effects of Nd123/MgO Thin Film and MgO Single-crystal Seeds in Isothermal Solidification of YBaCuO/Ag.” J. Mater. Res. 15, No. 8 (2000).
33 C. Cai, H. Mori, H. Fujimoto, H. Liu, S. Dou, “Crystal growth patterns in MgO seeded Y1.8Ba2.4Cu3.4Oy/Ag melt-texturing process.” Physica C 357-360, 734 (2001).
34 C. Cai and H. Fujimoto, “Stable production of large single-domain Y1.8Ba2.4Cu3.4Oy/Ag by isothermal solidification.” Physica C 357-360, 709 (2001).
35 H. Fujimoto, H. Ozaku, E. Ohtabara, “Sm–Ba–Cu–O bulk superconductors melt processed in air, using Nd123/MgO thin film cold seeding.” Physica C 386, 198 (2003).
36 M. Oda, X. Yao, Y. Yoshida and H. Ikuta, “Melt-textured growth of (LRE)–Ba–Cu–O by a cold-seeding method using SmBa2Cu3Oy thin film as a seed.” Supercond. Sci. Technol. 22, 075012 (6pp) (2009).
37 C. J. Kim, Y. A. Jee and G. W. Hong, “Variables affecting the fabrication of single grain YBa2Cu3O7-y superconductors by the top-seeded melt growth process.” Supercond. Sci. Technol. 13, 709 (2000).
38 C. J. Kim, Y. A. Jee, S. C. Kwon, T. H. Sing and G. W. Hong, “Control of YBCO growth at the compact/substrate interface by bottom seeding and Yb2O3 coating in seeded melt-growth processed YBCO oxides using a MgO substrate.” Physica C 315, 263-270 (1999).
39 Y. Nakamura, A. Endo and Y. Shiohara, “The relation between the undercooling and the growth rate of YBa2Cu3O6+x superconductive oxide.” J. Mater. Res. 11, 1094 (1996).
40 A. Endo, H.S. Chauhan, Y. Nakamura and Y. Shiohara, “Relationship between growth rate and undercooling in Pt-added Y1Ba2Cu3O7−x.” J. Mater. Res. 11, 1114 (1996).
41 M. Kambara, N. Hari Babu, Y. H. Shi, D.A. Cardwell, “Growth of melt-textured Nd-123 by hot seeding under reduced oxygen partial pressure.” J. Mater. Res. 16, 1163 (2001).
42 N. Hayashi, P. Diko, K. Nagashima, S.I. Yoo, N. Sakai, M. Murakami, “Fabrication of large single-domain Sm123 superconductors by OCMG method.” Mat. Sci. Eng. B 53, 104 (1998).
43 W. Lo, D.A. Cardwell, “Investigation of the controlled growth of large undoped and Pt-containing YBCO pseudo-crystals.” Mat. Sci. Eng. B 53, 45 (1998).
44 S. M. Rao, J. K. Srivastava, K. S. Law, R. H. Chang, H. I. Chung and M. K. Wu, “Growth mechanism in the crystallization of YBa2Cu3O6+ from peritecitc melts.” Supercond. Sci. Technol. 14, 958-965 (2001).
45 M. Morita, K. Kimura, K. Miyamoto, K. Sawano and M. Tanaka, “Process for forming composite film on aluminum or aluminum alloy article surface and resulting product.” US Patent 5308709 (1994).
46 T. Meignan, P. J. Mcginn and C. Varansi, “Seeded melt texture growth processing of YBa2Cu3O6+x with Yb2O3 coatings.” Supercond. Sci. Technol. 10, 109-112 (1997).
47 D. Shi, K. Lahiri, D. Qu and S. Sagar, “Surface nucleation, domain growth mechanisms, and factors dominating superconducting properties in seeded melt grown YBa2Cu3Ox.” J. Mater. Res., 12, no.11, 3036-3045 (1997).
48 T Y Li, L Cheng, S B Yan, L J Sun, X Yao, Y Yoshida and H Ikuta,” Growth and superconductivity of REBCO bulk processed by a seed/buffer layer/precursor construction” Supercond. Sci. Technol, 23(2010).
49 Difan Zhou, Kun Xu, Shogo Hara, Beizhan Li, Zigang Deng, Keita Tsuzuki and Mitsuru Izumi,” MgO-buffer layer induced texture growth of RE-Ba-Cu-O bulk” Supercond. Sci. Technol. 25 025022 (2011).
50 王上瑜,“新穎薄膜晶種成長技術於大尺寸釔鋇銅氧超導晶體之研究”,國立成功大學材料科學與工程研究所碩士論文, 101年7月
51 Chia-Ming Yang, Shang-Yu Wang, Yi-Chang Huang, Po-Wei Chen, In-Gann Chen, and Maw-Keun Wu, ” The Optimal Growth of Single Grain Bulk Y–Ba–Cu–O Superconductors With Nd–Ba–Cu–O Thin Film Seed” IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY, VOL. 23, NO. 3,(2013).
52 Ch. Krauns, M. Tagami, Y. Yamada, M. Nakamura, and Y. Shiohara, “Wetting between prospective crucible materials and the Ba-Cu-O melt” Mater. Res 9, 6(1994).
53 Yong Feng, Lian Zhou, J.G. Wen, N. Koshizuk, ”Flux pinning and flux creep in Sn-doped powder melting processed YBCO” Physica C ,289 ,216-222(1997).
54 J. G. Ossandon, J.R. Thompson, D. K. Christen, B.C. Sales, Yangren Sun, K. W. Lay, “Flux-creep studies of vortex pinning in an aligned YBa2Cu3O7–δ superconductor with oxygen deficiencies δ≤0.2” PHYSICAL B, 46,5(1992)