钙钛矿型稀土钴酸盐的热电性质研究
摘要
进入21世纪以来,随着全球环境污染和能源危机的日益严重,以及对人类可持续发展的广泛关注,开发新型环保的替代能源已经越来越受到世界各国的重视。热电材料是一种将热能和电能相互转换的功能材料。其中,氧化物热电材料作为一种新型的能源转化材料受到越来越广泛的重视,其最大优点是可以在氧化气氛的高温下长期工作,大多数无毒性、无污染而且制备简单。因此,研究氧化物热电材料具有十分重要的意义。本文以探索提高热电材料的热电性能为目的,对LaCoO_3热电材料掺杂Ca,Sr元素,深入分析了掺杂元素和掺杂量对LaCoO_3材料的输运以及热电性能的影响。
本论文使用传统的固相反应法制备了掺杂的系列样品La_(1-x)Ca_xCoO_3 (x=0.05,0.1,0.2,0.3)和La_(1-x)Sr_xCoO_3 (x=0,0.1,0.2,0.25,0.3)。通过XRD分析显示,合成的样品均为单相。对样品磁学性能的分析发现,掺杂后的LaCoO_3样品具有自旋玻璃性质。通过对样品高温电阻率的研究发现,相对于未掺杂的LaCoO_3,掺杂后能够显著降低样品的电阻率。电阻率的下降主要是因为掺杂改变了样品中钴离子的平均价态,使部分的Co3+离子变为Co4+离子,进而引入了大量的空穴载流子,致使电阻率下降。对于样品的高温导电机制进行了分析,分析发现在部分温区符合绝热小极化子跳跃导电模型。系统研究了La_(1-x)Ca_xCoO_3 (x=0.05,0.1,0.2,0.3)和La_(1-x)Sr_xCoO_3 (x=0,0.1,0.2,0.25)系列样品的低温热电性能。研究发现LaCoO_3经过掺杂以后,能够明显降低样品的电阻率,而且同时能够保证样品的热电势绝对值保持在较大的数值。此外,在LaCoO_3的La位掺杂后,由于晶格畸变影响,增加了声子散射,使得热导率降低,。之后随着掺杂量的增加,由于电阻率显著降低,使得热导率略微增加。基于以上的分析表明通过在La位进行掺杂能够有效的提高LaCoO_3材料的热电性能。计算了系列样品的热电优值,其中ZT值最高的为其中La_(0.8)Sr_(0.2)CoO_3,在157K左右达到最大值0.11。
Since entering the 21st century, with the global environmental pollution and the increasingly serious energy crisis, as well as a wide range of sustainable human development concerns, the development of new environmentally-friendly alternative sources of energy had been receiving increasing attention around the world. Thermoelectric materials is a thermal and electrical energy can be converted each other functional materials. As potential candidates for a new thermoelectric material several electronic conductive oxides have attracted more and more research interests. These oxides have many advanced properties, which can be used at high temperature for long time, nontoxic, without pollutions and can be maked easily. Therefore , it is getting more and more important to study the thermoelectric oxide materials. The thesis was originally intended to improve the thermoelectric performance for the thermoelectric materials in the use of Ca,Sr as the dopants in the p type LaCoO_3 material. This paper analyzed the impact of the doped elements and the doped density for the transport and thermoelectrical properties.
In this thesis, polycrystalline samples La_(1-x)Ca_xCoO_3(x=0.05,0.1,0.2,0.3) and La_(1-x)Sr_xCoO_3(x=0,0.1,0.2,0.25) were prepared by the traditional solid-state reaction method. From the X-ray diffraction (XRD) data, the all prepared samples exhibited single-phase structure. From the magnetic properties,the La1-xRxCoO_3 are the spin-glass simple. From the investigation of the resistivity in the high temperature, it was seen that the resistivity of the doped La1-xRxCoO_3 samples significantly decreased compared the undoped semiconductor-like LaCoO_3. The reduction of the resistivity as doping at first should be attributed to the change of the valence of Co ions by Ca and Sr elements substitution. The substitution will induce Co4+ in the matrix of Co3+, and create a large number of hole carriers. Analyzing the conduction mechanism, the resistivity is consist with the adiabatic small polaron hopping conduction model in somepart of the high temperature. Systematic investigation the low temperature thermoelectric properties of the La_(1-x)Ca_xCoO_3 (x=0.05,0.1,0.2,0.3) and La_(1-x)Sr_xCoO_3(x=0,0.1,0.2,0.25,0.3) samples. After use Ca and Sr elements as a dopant in LaCoO_3 material, the resistivity can significantly decrease. Meanwhile, the absolute value of the thermal power can maintain at a good value. Besides, doping at La site with Ca and Sr ions in LaCoO_3 will enhance the distortion of lattice, which may be enhance the scattering of the phonon in the result of lowering the thermal conductivity,and then the resistivity can significantly decrease,which can be enhanced the result of lowering the thermal conductivity. Based on the analysis, doping at La site with rare Ca and Sr elements may improve the thermoelectric performance of LaCoO_3 material. We calculated the figure of merit of the samples, obtaining the figure of merit 0.11 at about 157K in La_(0.8)Sr_(0.2)CoO_3 sample.
本论文使用传统的固相反应法制备了掺杂的系列样品La_(1-x)Ca_xCoO_3 (x=0.05,0.1,0.2,0.3)和La_(1-x)Sr_xCoO_3 (x=0,0.1,0.2,0.25,0.3)。通过XRD分析显示,合成的样品均为单相。对样品磁学性能的分析发现,掺杂后的LaCoO_3样品具有自旋玻璃性质。通过对样品高温电阻率的研究发现,相对于未掺杂的LaCoO_3,掺杂后能够显著降低样品的电阻率。电阻率的下降主要是因为掺杂改变了样品中钴离子的平均价态,使部分的Co3+离子变为Co4+离子,进而引入了大量的空穴载流子,致使电阻率下降。对于样品的高温导电机制进行了分析,分析发现在部分温区符合绝热小极化子跳跃导电模型。系统研究了La_(1-x)Ca_xCoO_3 (x=0.05,0.1,0.2,0.3)和La_(1-x)Sr_xCoO_3 (x=0,0.1,0.2,0.25)系列样品的低温热电性能。研究发现LaCoO_3经过掺杂以后,能够明显降低样品的电阻率,而且同时能够保证样品的热电势绝对值保持在较大的数值。此外,在LaCoO_3的La位掺杂后,由于晶格畸变影响,增加了声子散射,使得热导率降低,。之后随着掺杂量的增加,由于电阻率显著降低,使得热导率略微增加。基于以上的分析表明通过在La位进行掺杂能够有效的提高LaCoO_3材料的热电性能。计算了系列样品的热电优值,其中ZT值最高的为其中La_(0.8)Sr_(0.2)CoO_3,在157K左右达到最大值0.11。
Since entering the 21st century, with the global environmental pollution and the increasingly serious energy crisis, as well as a wide range of sustainable human development concerns, the development of new environmentally-friendly alternative sources of energy had been receiving increasing attention around the world. Thermoelectric materials is a thermal and electrical energy can be converted each other functional materials. As potential candidates for a new thermoelectric material several electronic conductive oxides have attracted more and more research interests. These oxides have many advanced properties, which can be used at high temperature for long time, nontoxic, without pollutions and can be maked easily. Therefore , it is getting more and more important to study the thermoelectric oxide materials. The thesis was originally intended to improve the thermoelectric performance for the thermoelectric materials in the use of Ca,Sr as the dopants in the p type LaCoO_3 material. This paper analyzed the impact of the doped elements and the doped density for the transport and thermoelectrical properties.
In this thesis, polycrystalline samples La_(1-x)Ca_xCoO_3(x=0.05,0.1,0.2,0.3) and La_(1-x)Sr_xCoO_3(x=0,0.1,0.2,0.25) were prepared by the traditional solid-state reaction method. From the X-ray diffraction (XRD) data, the all prepared samples exhibited single-phase structure. From the magnetic properties,the La1-xRxCoO_3 are the spin-glass simple. From the investigation of the resistivity in the high temperature, it was seen that the resistivity of the doped La1-xRxCoO_3 samples significantly decreased compared the undoped semiconductor-like LaCoO_3. The reduction of the resistivity as doping at first should be attributed to the change of the valence of Co ions by Ca and Sr elements substitution. The substitution will induce Co4+ in the matrix of Co3+, and create a large number of hole carriers. Analyzing the conduction mechanism, the resistivity is consist with the adiabatic small polaron hopping conduction model in somepart of the high temperature. Systematic investigation the low temperature thermoelectric properties of the La_(1-x)Ca_xCoO_3 (x=0.05,0.1,0.2,0.3) and La_(1-x)Sr_xCoO_3(x=0,0.1,0.2,0.25,0.3) samples. After use Ca and Sr elements as a dopant in LaCoO_3 material, the resistivity can significantly decrease. Meanwhile, the absolute value of the thermal power can maintain at a good value. Besides, doping at La site with Ca and Sr ions in LaCoO_3 will enhance the distortion of lattice, which may be enhance the scattering of the phonon in the result of lowering the thermal conductivity,and then the resistivity can significantly decrease,which can be enhanced the result of lowering the thermal conductivity. Based on the analysis, doping at La site with rare Ca and Sr elements may improve the thermoelectric performance of LaCoO_3 material. We calculated the figure of merit of the samples, obtaining the figure of merit 0.11 at about 157K in La_(0.8)Sr_(0.2)CoO_3 sample.
引文
1 Gerald Mahan, Brian Sales and Jeff Sharp. Thermoelectric Materials: New Approaches to An Old Problem. Physics Today 1997, 50(2): 42~47
2 Francis J. DiSalvo. Thermoelectric cooling and power generation. Science 1999, 285(5428): 703~706
3 D. Y. Chung, T. Hogan, P. Brazis, et al. CsBi4Te6: a High-performance Thermoelectric Material for Low-temperature Applications. Science 2000, 287(5455): 1024~1027
4 R. Funahashi and M. Mikami. A Portable Thermoelectric-power-generating module composed of oxide devices. J. Appl. Phys. 2006, 99: 066117(1~3)
5 J. G. Noudem, S. Lemonnier, M. Prevel, et al. Thermoelectric ceramics for generators. J. Europ. Ceram. Soc. 2008, 28: 41~48
6 T. Okamoto, S. Horii, T. Uchikoshi, et al. Fabrication of Multilayered Oxide Thermoelectric Modules by Electrophoretic Deposition Under High Magnetic Fileds. Appl. Phys. Lett. 2006, 89, 081912(1~3)
7 M. Zebarjadi, A. Shakouri, and K. Esfarjani. Thermoelectric Transport perpendicular to Thin-film Heterostructures Calculated using the Monte Carlo Technique. Phys. Rev. B 2006, 74, 195331(1~6)
8 I. Terasaki,Y.Sasago, Uchinokura K.Large thermoelectric power in NaCo_2O_4 single crystals [J].Phys Rev B, 1997, 56 (12):685~687.
9 I.Mikio.Synthesis of NaxCo_2O_4 thermoelectric oxides by the polymerized complex method [J]. Scripta Materialia, 2003, 48: 403~408.
10 C.Fouassier,G.Matejka,J.Reau,et al. Sur de eouveauxbronzes oxygenes de formule NaxCoO2 (x≤1) l e systeme cobaltoxygene-sodium[J].J Solid State Chem,1973,( 6) :532~537
11 Y.Ando, N.Miyamoto.Electronic structure of NaxCo_2O_4[J].MaterialsLetters, 2001, 49: 262~266
12 Shechtman,D.Blech,D.Gratias,et a1.Metallic phase withlong-range orientation order and no transnational symmetry [J]. PhysRev Lett, 1984, 53: 195l~1953
13 I. Mikio, K.Shigeu. Synthesis of NaxCo_2O_4 thermoelectric oxidewith crystallographic anisotropy by chemical solution process [J].Science and Technology of Advanced Materials, 2004, (5):125~131
14 T. Itoh, T. Kawata.Transport properties in (Na,Ca)Co_2O_4 ceramics[A]. 17thInternational Conference on Thermoelectrics [C].Japan:Nagoga, 1998. 595~597
15 O. Yasuthiro, R. Ishikawa. Crystal structure, electric andmagnetic properties of cobaltite b-NaxCo_2O_4[J]. Journal Solid StateChem, 2002,166: 177~181
16 Jie-xu Gao, R. Funahashi, S.Masahiro,et al. Thermoelectric properties of the the Bi and Na substituted Ca3Co4O9 system[J]. Appl Phys Lett, 2002, 80: 3 760~3762
17 Si-wen Li. Synthesis and thermoelectric properties of the new ox ide ceramics SrxCa3-xCo4O9+δ[J]. Ceramics International, 2001, 27: 321~324
18 A. C. Masset, C. Michel, A. Maignan, et al. Misfit-layeredcobaltite with an anisotropic giant magnetoresistance Ca3Co4O9 [J].Phys Rev B, 2000, 62: 166~175
19 R. M. Funahashi. Thermoelectric properties in single crystalsof Ca-Co-O system[A]. 21th International Conference on Thermoelelctronics[C]. 2002, 62: 166~175
20 J. Nan, J. Wu, Y. Deng, et al. Synthesis and thermoelectric properties of (NaxCa1-x)Co4O9 ceramics [J]. Journal of the EuropeanCeramic Society, 2003, 23:859~863
21闵新民,邢学玲,张文芹.钴盐热电材料研究进展[J].功能材料,2005, (4) :35~38
22 J. A. Mydosh. spin Glasses:an experimental introduction. Taylor&Francis London. Washington, DC, 1993: 1~18
23 Suzanne R. English, J.Wu,and C.Leighton. Thermal excited spin-disorder contribution to the resistivity of LaCoO3. Physical Review B.2002, 65: 220407~220412
24严纯华,黄云辉,朱涛等人.稀土锰酸盐纳米颗粒复合体系的软化学制备及磁电阻增强效应.物理.2001,2(30):100~105
25 Antoine Maignan, Christine Martin, Ninh Nguyen et al. Magenetoresistance in the ferromagnetic perovskite SrFe1-xCoxO3. Solid State Sciences. 2001: 357~363
26 Yun-Hui Huang, Zhi-Gang Xu et al. Soft chemical synthesis and transport properties of La0.7Sr0.3MnO3 granular perovskites. Solid State Communication. 2000: 11443~11447
27 Vladimir Golovanov and Laszio Mihaly. Magnetoresistence in La1-xSrxCoO3 for
0.05≦x≦0.25. Physical review B.1996, 53(13): 8207~8210
28 G.L.Yuan, J-M.Liu, Z. G. Liu et al.Preparation of nanosized La0.7Sr0.3MnO3/Pr0.5Sr0.5MnO3 composites with enhanced low-field magnetoresistance. Materials Chemistry and Physics. 2002: 75161~165
29 T.Zhu, C.H.Yan, Z.M.Wang, et al. Low-field magentoresistance in La1/3Sr2/3MnO3 granular composites by a sol-gel coating process. Solid State Communication.2001, 117: 471~475
30 A.Maigan, C.Martin, M.Hervieu et al. Instragrain and intergrain magnetoresistance in Mn,Fe/Mo and Co simple,double and oxygen deficient perovskite oxide. J. Of Magnetic Materials. 2002, 2: 11173~179
31 C. Zobel, M. Kriener, D.Bruns et al. Evidence for a low-spin to intermediate-spin state transition in LaCoO3.Physical Review B. 2002, 66: 020402(1~4)
32 Yosuke Fujine, Hiroyuki Fujishiro et al.Anomalous phonon scattering by Jahn–Teller active Co intermediate spins in LaCoO3 and doped LaCoO3. Physica B. 359–361 (2005) 1360~1362
33 W. Koshibae, K. Tsutsui, and S. Maekawa, Thermopower in cobalt oxides. Physical Review B. 62-11(2000):6869~6872
34 Xiangfan Xu, Lizhen Jiang et al, Relationship between spin state of Co ions and thermopower in La1?xSrxCoO3 (0≦x≦0.5). Physica Letters A. 351 (2006) 431~434
35 Nguyen Xuan Phuc, Nguyen Van Khiem, Dao NguyenHoai nam. Field dependence of zero-field-cooled magnetization of La1-xSrxCoO3(x=0.05-0.5).J. Of Magnetism and Magnetic Materials.2002, 242-245: 754~756
36 A. V. Samoilov, G. Beach, C. C. Fu et al. Giant Spontaneous Hall Effect and magnetoresistence in La1-xCaxCoO3(0.1≦x≦0.5). J. Of Applied Physics. 1998, 83(11):6998~7000
37夏正才,唐超群,La1-xSrxMnO3,阴极材料的导电机理研究,物理学报,1999,45(s):1515~1522
38 C. Oliva, Lforni, Characterisation by EPR and other techniuques of LaxCexCoO3 perovskite catalysts for methane flameless combustion, Applied catalysis A, 2001,205:245~252
39 J. Wu and C. Leighton. Galssy ferromagentic and magnetic phase separation in La1-xSrxCoO3.Physical review B.2003,67:174408(1~15)
40 M. Hofmann, T. Lorenz, G. S. Uhrig, H. Kierspel, O. Zabara, A.Freimuth, H. Kageyama, and Y. Ueda, Strong Damping of Phononic Heat Current by Magnetic Excitations in SrCu2(BO3)2. Phys. Rev. Lett.2001, 87: 047202 (1~4)
41 J. Baier, S. Jodlauk, M. Kriener, A. Reichl, C. Zobel, H. Kierspel,A. Freimuth,and T. Lorenz.Spin-state transition and metal-insulator transition in La_(1-x)Eu_xCoO_3, Phys. Rev. B , 2005, 71: 014443(1~10)
42 Shmgo Tsubouchi, Toru kyomen, Mitsuru Itoh, et al. Simultaneous metalinsulator and spin-state transition in Pr0.5Ca0.5CoO3 . Physical Review B. 2002, 66: 052418(1~15)
43 H. Takano, S. Hikichi, S. Murayama et al. Magnetic properties of concertrated melt-spun Fe-Y amorphous alloys. J. Of Magnetism and Magnetic Materials: 2002, 239: 518~520
44 J.A. Mydosh. Spin glasses an experimental introduction. Taylor &Francis London. Washington, DC. 1993: 1~18
45 Takao Moriand, Hiroaki Mamiya. Dynamical Properties of a Crystalline Rare-Earth Boron Cluster Spin-Glass System. Phys.Rev.B.2003, 68:214422-2~214422-3
46 P.Mandal, P.Choudhury, S.K.Biswas and B.Ghosh.Transport and Magnetic Properties of La1-xBaxCoO3. Phys.Rev.B.2004, 70:104407-2~104407-3
47 M.A. Senaris-Rodriguez and J.B Goodenough. LaCoO3 Revisted. Journal of Solid State Chemistry 116(1995),224~231
48 J.A.Mydoson. Spin Glasses:an Experimental Introduction. Taglor and Francis, 1993:29~35
2 Francis J. DiSalvo. Thermoelectric cooling and power generation. Science 1999, 285(5428): 703~706
3 D. Y. Chung, T. Hogan, P. Brazis, et al. CsBi4Te6: a High-performance Thermoelectric Material for Low-temperature Applications. Science 2000, 287(5455): 1024~1027
4 R. Funahashi and M. Mikami. A Portable Thermoelectric-power-generating module composed of oxide devices. J. Appl. Phys. 2006, 99: 066117(1~3)
5 J. G. Noudem, S. Lemonnier, M. Prevel, et al. Thermoelectric ceramics for generators. J. Europ. Ceram. Soc. 2008, 28: 41~48
6 T. Okamoto, S. Horii, T. Uchikoshi, et al. Fabrication of Multilayered Oxide Thermoelectric Modules by Electrophoretic Deposition Under High Magnetic Fileds. Appl. Phys. Lett. 2006, 89, 081912(1~3)
7 M. Zebarjadi, A. Shakouri, and K. Esfarjani. Thermoelectric Transport perpendicular to Thin-film Heterostructures Calculated using the Monte Carlo Technique. Phys. Rev. B 2006, 74, 195331(1~6)
8 I. Terasaki,Y.Sasago, Uchinokura K.Large thermoelectric power in NaCo_2O_4 single crystals [J].Phys Rev B, 1997, 56 (12):685~687.
9 I.Mikio.Synthesis of NaxCo_2O_4 thermoelectric oxides by the polymerized complex method [J]. Scripta Materialia, 2003, 48: 403~408.
10 C.Fouassier,G.Matejka,J.Reau,et al. Sur de eouveauxbronzes oxygenes de formule NaxCoO2 (x≤1) l e systeme cobaltoxygene-sodium[J].J Solid State Chem,1973,( 6) :532~537
11 Y.Ando, N.Miyamoto.Electronic structure of NaxCo_2O_4[J].MaterialsLetters, 2001, 49: 262~266
12 Shechtman,D.Blech,D.Gratias,et a1.Metallic phase withlong-range orientation order and no transnational symmetry [J]. PhysRev Lett, 1984, 53: 195l~1953
13 I. Mikio, K.Shigeu. Synthesis of NaxCo_2O_4 thermoelectric oxidewith crystallographic anisotropy by chemical solution process [J].Science and Technology of Advanced Materials, 2004, (5):125~131
14 T. Itoh, T. Kawata.Transport properties in (Na,Ca)Co_2O_4 ceramics[A]. 17thInternational Conference on Thermoelectrics [C].Japan:Nagoga, 1998. 595~597
15 O. Yasuthiro, R. Ishikawa. Crystal structure, electric andmagnetic properties of cobaltite b-NaxCo_2O_4[J]. Journal Solid StateChem, 2002,166: 177~181
16 Jie-xu Gao, R. Funahashi, S.Masahiro,et al. Thermoelectric properties of the the Bi and Na substituted Ca3Co4O9 system[J]. Appl Phys Lett, 2002, 80: 3 760~3762
17 Si-wen Li. Synthesis and thermoelectric properties of the new ox ide ceramics SrxCa3-xCo4O9+δ[J]. Ceramics International, 2001, 27: 321~324
18 A. C. Masset, C. Michel, A. Maignan, et al. Misfit-layeredcobaltite with an anisotropic giant magnetoresistance Ca3Co4O9 [J].Phys Rev B, 2000, 62: 166~175
19 R. M. Funahashi. Thermoelectric properties in single crystalsof Ca-Co-O system[A]. 21th International Conference on Thermoelelctronics[C]. 2002, 62: 166~175
20 J. Nan, J. Wu, Y. Deng, et al. Synthesis and thermoelectric properties of (NaxCa1-x)Co4O9 ceramics [J]. Journal of the EuropeanCeramic Society, 2003, 23:859~863
21闵新民,邢学玲,张文芹.钴盐热电材料研究进展[J].功能材料,2005, (4) :35~38
22 J. A. Mydosh. spin Glasses:an experimental introduction. Taylor&Francis London. Washington, DC, 1993: 1~18
23 Suzanne R. English, J.Wu,and C.Leighton. Thermal excited spin-disorder contribution to the resistivity of LaCoO3. Physical Review B.2002, 65: 220407~220412
24严纯华,黄云辉,朱涛等人.稀土锰酸盐纳米颗粒复合体系的软化学制备及磁电阻增强效应.物理.2001,2(30):100~105
25 Antoine Maignan, Christine Martin, Ninh Nguyen et al. Magenetoresistance in the ferromagnetic perovskite SrFe1-xCoxO3. Solid State Sciences. 2001: 357~363
26 Yun-Hui Huang, Zhi-Gang Xu et al. Soft chemical synthesis and transport properties of La0.7Sr0.3MnO3 granular perovskites. Solid State Communication. 2000: 11443~11447
27 Vladimir Golovanov and Laszio Mihaly. Magnetoresistence in La1-xSrxCoO3 for
0.05≦x≦0.25. Physical review B.1996, 53(13): 8207~8210
28 G.L.Yuan, J-M.Liu, Z. G. Liu et al.Preparation of nanosized La0.7Sr0.3MnO3/Pr0.5Sr0.5MnO3 composites with enhanced low-field magnetoresistance. Materials Chemistry and Physics. 2002: 75161~165
29 T.Zhu, C.H.Yan, Z.M.Wang, et al. Low-field magentoresistance in La1/3Sr2/3MnO3 granular composites by a sol-gel coating process. Solid State Communication.2001, 117: 471~475
30 A.Maigan, C.Martin, M.Hervieu et al. Instragrain and intergrain magnetoresistance in Mn,Fe/Mo and Co simple,double and oxygen deficient perovskite oxide. J. Of Magnetic Materials. 2002, 2: 11173~179
31 C. Zobel, M. Kriener, D.Bruns et al. Evidence for a low-spin to intermediate-spin state transition in LaCoO3.Physical Review B. 2002, 66: 020402(1~4)
32 Yosuke Fujine, Hiroyuki Fujishiro et al.Anomalous phonon scattering by Jahn–Teller active Co intermediate spins in LaCoO3 and doped LaCoO3. Physica B. 359–361 (2005) 1360~1362
33 W. Koshibae, K. Tsutsui, and S. Maekawa, Thermopower in cobalt oxides. Physical Review B. 62-11(2000):6869~6872
34 Xiangfan Xu, Lizhen Jiang et al, Relationship between spin state of Co ions and thermopower in La1?xSrxCoO3 (0≦x≦0.5). Physica Letters A. 351 (2006) 431~434
35 Nguyen Xuan Phuc, Nguyen Van Khiem, Dao NguyenHoai nam. Field dependence of zero-field-cooled magnetization of La1-xSrxCoO3(x=0.05-0.5).J. Of Magnetism and Magnetic Materials.2002, 242-245: 754~756
36 A. V. Samoilov, G. Beach, C. C. Fu et al. Giant Spontaneous Hall Effect and magnetoresistence in La1-xCaxCoO3(0.1≦x≦0.5). J. Of Applied Physics. 1998, 83(11):6998~7000
37夏正才,唐超群,La1-xSrxMnO3,阴极材料的导电机理研究,物理学报,1999,45(s):1515~1522
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39 J. Wu and C. Leighton. Galssy ferromagentic and magnetic phase separation in La1-xSrxCoO3.Physical review B.2003,67:174408(1~15)
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