熱電材料在溫差發電及熱電致冷方面都具有廣泛的應用，而陶瓷熱電材料更具有成本低廉、無汙染等之優點，是備受期待的材料之一。La1-xSrxCuO2.5-δ為具有氧缺陷之perovskite結構，呈現金屬型的導電性，其電子導電率良好，但在熱電性質方面之研究較少。
本研究旨在檢討鍶的摻雜對於銅酸鑭粉體之燒結行為與燒結體熱電性質之影響。本研究以有機物前導法 (Polymerized Complex method)製備含鍶之銅酸鑭粉末，以熱膨脹儀分析其燒結收縮曲線，以XRD鑑定結晶相，以阿基米德法量測燒結體密度，以SEM觀察燒結體晶粒大小，以Seebeck係數/電阻量測系統及雷射熱導儀量測熱電性質。
含鍶之銅酸鑭粉體是經550℃/1 h煆燒合成而得。經1100℃氧分壓流量為300 ml/min下燒結2 h所得的塊材，未含Sr的燒結體相對密度最低，為87.8 %，含Sr (20~30 at.%)的燒結體相對密度皆高於90%。未含鍶之燒結體，其晶粒大小為8.8μm；所有含鍶的燒結體晶粒大小為2.5~3.1μm，鍶的添加可抑制銅酸鑭的晶粒成長。
在燒結體的熱電性質方面，經由鍶摻雜的燒結體其電傳導係數顯著的提升，且隨著Sr含量的增加有先增後減的趨勢，含26 at.% Sr的燒結體有最高的電傳導係數，在325 K時其值為959.45 S/cm。經由鍶摻雜的燒結體之Seebeck係數則大幅減少，未含鍶之燒結體，其在500 K時之Seebeck係數值為390.4 μV/K，含鍶者之Seebeck係數僅為-5.6~2.3 μV/K。未含鍶之燒結體有最大的功率因子其在500 K之值為3.22μW/mK2。

Thermoelectric materials and devices have widely used in the fields of energy conversion, sensors, and thermoelectric cooling. The ceramic thermoelectric materials are also well-known for no noise and no pollution. La1-xSrxCuO2.5-δ shows the metallic electrical conductivity owing to oxygen-defect perovskite structure. Its electronic conductivity is good, therefore, it can be considered as one kind of thermoelectric materials.
The effect of strontium-doped on sintering behavior and thermoelectric properties of lanthanum copper oxides were investigated in this study. The precursor powders were prepared by polymerized complex method. After calcined at 550 ℃/1 h and sintered at 1100 ℃/2 h at oxygen atmosphere, all strontium-doped sintered bodies have relative density higher than 90%, except for 0 at.% Sr samples. The grain size of sintered lanthanum copper oxide is 8.8μm and the grain size of La1-xSrxCuO2.5-δ (x = 0.2~0.3) sintered bodies are about 2.5 ~ 3.1μm. Doping strontium can inhibit the grain growth of lanthanum copper oxides.
In terms of thermoelectric properties, the electrical conductivity increases as Sr-doped, the highest electric conductivity with the value of 959.5 S/cm occurred at 300 K for the La0.75Sr0.26CuO2.5-δ sintered body, However, the Seebeck coefficient decreases as Sr-doped, the highest Seebeck coefficient with the value of 390.4 μV/K occurred at 325 K for the La2Cu2O5 (x = 0), the highest power factor with the value of 3.22 μW/mK2 occurred at 500 K for the La2Cu2O5 (x = 0).

1. N. Murayama, S. Sakaguchi, F. Wakai, E. Sudo, A. Tsuzuki and Y. Torii, ” New Oxygen-Deficient Perovskite Phase, La1-xSrxCuO3-y (0.20≦x≦0.25)”, J. Appl. Phys., 27, No.1, L55-L56 (1988).
2. H. C. Yu, K. Z. Fung, “La1−xSrxCuO2.5−δ as new cathode materials for intermediate temperature solid oxide fuel cells”, Materials Research Bull. 38, 231-239 (2003).
3. C. Michel, L. Er-Rakho and B. Raveau, “La8-xSrxCu8O20: An Oxygen-Deficient Perovskite Built of CuO6, CuO5 and CuO4 Polyhedra”, J. Phys. Chem. Solids 49, 451-455 (1988).
4. Xifeng Ding, Ling Gao, Yingjia Liu, Yifeng Zhen & Lucun Guo, “Thermal expansion and electrochemical properties of La0.7AE0.3CuO3−δ (AE=Ca, Sr, Ba) cathode materials for IT-SOFCs”, J. Electroceram 18:317–322 (2007).
5. J. F. Bringley, B. A. Scott, S. J. Placa, R. F. Boehme, T. M. Shaw, M. W. McElfresh, S. S. Trail, and D. E. Cox, “Synthesis of the defect perovskite series LaCuO3–δ with copper valence varying from 2+ to 3+”, Nature, 347, 263 (1990).
6. H. J. Goldsmid, D. M. Rowe, and B. Raton, in CRC Handbook of Thermoelectrics, Chap. 3-4 (1995).
7. D. M. Rowe. CRC Handbook of Thermoelectrics. CRC Press, 1994, A-3, pp. 19-25.
8. R. Richman, “Prospects for efficient thermoelectric materials in the near term”, San Diego, CA., 2002, DARPA/DOE High Efficient Thermoelectric.
9. TE Technology Inc.” Frequently asked questions on thermoelectric”, [Online] 12 2005. http://www.tetech.com/techinfo/#faqs.
10. L. Bell, “Technology requirements for solid state power conversion”, 2004. DOE/EPRI High Efficient Thermoelectric Workshop.
11. 祝學成，廣小榮，”熱電材料的研究現況及發展趨勢”, (佛山市華夏建築陶瓷研究開發中心, 廣東佛山 528061). Foshan ceramics vol.18 No6. (serial No.140)
12. F. Stabler, “Automotive applications for high efficiency thermoelectric”, San Diego, CA., 2002, DARPA/DOE High Efficient Thermoelectric Workshop.
13. E. Thacher, “Electric energy generation from the exhaust of a light truck” 2004, DOE/EPRI High Efficient Thermoelectric Workshop.
14. Hi-Z Technology Inc. “Thermoelectric truck engine generator”, [Online] 12 2005. http://www.hi-z.com/websit07.htm.
15. Hong Lan, Ren Shan, P.M. Vereecken, L. Sun, P.C. Searson, “半導體熱電材料Bi1-xSbx薄膜的電化學製備”。
16. Jiang Yi-Ping, Jia Xiao-Peng, Ma Hong-An, Su Tai-Chao, Dong Nan, Deng Le, ”高壓合成La填充型CoSb3方鈷礦熱電材料及其電輸運性能”。
17. 井群、司海剛、張世華、王淵旭，”室溫下矽與矽鍺合金的熱電性能研究”,(石河子大學生態物理重點實驗室師範學院物理系，新疆石河子832000)。
18. 張莉“γ-NaCo2O4氧化物熱電材料的化學法合成及熱電性能”, (材料複合新技術國家重點實驗室，新能源材料)。
19. A. Wold, B. Post, and E. Banks., “Lanthanum Rhodium and Lanthanum Cobalt Oxides”, J. Am. Chem. Soc., 79, 6365-6366 (1957).
20. M. P. Pechini, “Barium Titanium Citrate, Barium Titanate and Processes for Producing Same”, U.S. Pat., No. 3 231 328, Jan. 25, (1969).
21. J. W. Liu, Z. Zeng, Q. Q. Zheng, H. Q. Lin, “Effective Transfer Integrals for the Jahn-Teller Distortion in LaMnO3”, 60 (18), 12968-12973 (1999).
22. 高弘任，”檸檬酸法製備鋁酸鍶鈣螢光粉體及其光性質研究”，國立成功大學材料科學及工程學系，碩士論文，民國九十七年二月。
23. D. Hennings, W. Mayr, “Theraml Decomposition of (BaTi) Citrates into Barium Titanate”, J. Solid State Chem., 26, 329-338 (1978).
24. G. A. Hutchins, G. H. Maher, S. D. Ross, “Control of the Ba：Ti Ratio of BaTiO3 at a Value of Exactly 1 via Conversion to BaO．TiO2．3C6H8O7．6H2O”, Am. Ceram. Soc. Bull., 66 (4), 681-684 (1987).
25. M. S. G. Baythoun and F. R. Sale, “Production of Strontium-substituted Lanthanum Manganite Perovskite Powder by the Amorphous Citrate Process”, J. Mater. Sci., 17, 2757-2769 (1982).
26. P. A. Lessing, “Mixed-Cation Oxide Powders via Polymeric Precursors”, Am. Ceram. Soc. Bull., 68 (5), 1002-1007 (1989).
27. M. Kakihana, M. M. Milanova et al., “Polymerized Complex Route to Synthesis of Pure Y2Ti2O7 at 750°C Using Yttrium-Titanium Mixed-Metal Citric Acid Complex”, J. Am. Ceram. Soc., 79 (6), 1673-1676 (1996).
28. S. G. Cho, P. F. Johnson and R.A. Condrate, “Thermal decomposition of (Sr, Ti) organic precursor during the Pechini process”, J. Mater. Sci., 25, 4738-4744 (1990).
29. A. Roger, D. Souza, M. Saiful Islam and E. Ivers-Tiffee, “Formation and migration of cation defects in the perovskite oxide LaMnO3”, J. Mater. Chem., 9, 1621-1627 (1999).
30. J. B. Goodenogh, J. M. Longo, “Landolt-Bornstein New Series”, Speinger-Verlag Berlin and New York, V4. Parta. 126 (1970).
31. M. P. Pechini, “Method of Preparing Lead and Alkaline Earth Titanates and Niobates and Coationg Method Using the Same to Form a Capacitor”, U. S. Pat., No. 3 330 697, 11 (1967).
32. H. C. Yu, K. Z. Fung, “Role of strontium addition on the phase transition of lanthanum copper oxide from K2NiF4 to perovskite structure”, J. Alloys. Compd. 440, 62–68 (2007).
33. J. Remmel, J.Greek, G. Linker, O. Meyer, R. Smithey, B.Strehlau, G.C. Xiong, Physica C, 165, 212 (1990).
34. Y. Ichino, T. Nonoyama, M. Kaikawa, “Thermoelectric Properties of RE2-xMxCuO4 Oxide Sintering Bulks”, Elec. Com. Jap. 91,12 ,24-28, (2008).
35. J.E. Rodriguez , L.C. Moreno, “La1-xSrxCuO3-δ ceramics as new thermoelectric material for low temperature applications”, J. Mater. Sci., 65.46-48 (2011).
36. H. C. Yu, K. Z. Fung, “Effect of Sr addition on structure and conductivity of La1-xSrxCuO2.5-y perovskite”. Physica C. 262 220-226 (1996.)
37. J. B. Torrance, P. Lacorre, “why are some oxides metallic, while most are insulating?”, Physica C. 182 351-364 (1991).
38. M. Zahid, I. Arul. Raj, W. Fischer, F. Tietz, J.M. Serra Alfaro, “Synthesis and investigations on the stability of La0.8Sr0.2Cu2.4+δ at high temperatures”, Sci, soild state ionics 177, 3205-3210 (2006).
39. L. Er-Rakho, C. Michel, B. Raveau, “La8-xSrxCu8O20：An Oxygen-deficient perovskite built of CuO6, CuO5, and CuO4 polyhedral”, J. soild state chem. 73, 514-519 (1988).
40. 余河潔，”以鍶摻雜銅酸鑭做為中溫固態氧化物燃料電池陰極材料之研究”，國立成功大學材料科學及工程學系，博士論文，民國九十四年六月。
41. M.Z. Zhang , X.M. Liu , W.H. Su, “Preparation and performance of La1−xSrxCuO3−δ as cathode material in IT-SOFCs”, J. alloy. Compd. 395, 300-303 (2005).