成功大學博碩士論文系統

簡易檢索 / 詳目顯示

回結果列表

研究生：	陳士程 Chen, Shih-Cheng
論文名稱：	利用核磁共振技術研究窄贗能隙材料：CaxCo4Sb12與CeFe2Al10合金 NMR study of narrow pseudo-gap materials：CaxCo4Sb12 and CeFe2Al10 alloys
指導教授：	呂欽山 Lue, Chin-Shan
學位類別：	博士 Doctor
系所名稱：	理學院 - 物理學系 Department of Physics
論文出版年：	2011
畢業學年度：	99
語文別：	英文
論文頁數：	107
中文關鍵詞：	核磁共振、窄能隙、混成能隙
外文關鍵詞：	NMR, narrow gap, hybridization gap
相關次數：	點閱：58 下載：1
分享至:	分享至facebook 分享至twitter

查詢本校圖書館目錄查詢臺灣博碩士論文知識加值系統勘誤回報

對於樣品的量測，如磁化率、比熱、電阻…等，量測所得到的實驗數據為主要為材料巨觀上的表現，實驗的結果往往會受到外在雜質或樣品本身的不純度影響而造成對樣品的些許誤判。為了避免不純度影響了實驗的精準度，在微觀量測上，NMR就是一個很好的量測技術。由於每個原子核有其共振吸收頻率，因此NMR可以針對欲觀測的原子核進行探討，進而由所得數據得知其所處週遭環境的物理。在本篇論文中，我們對二種不同的半金屬化合物系統- CaxCo4Sb12 (x=0, 0.05, 0.13, 0.2) 和CeFe2Al10，利用核磁共振(NMR)技術進行其物理性質的研究。
第一部份為CaxCo4Sb12 (x=0, 0.05, 0.13, 0.2): 其母體CoSb3在熱電材料上有很大的潛力。藉由摻雜外來原子可增加聲子散射率，進而降低熱導率，提升ZT值。在我們的NMR研究上發現，對於低濃度(x≤0.13) Ca原子的摻雜下，我們的樣品表現出有一能隙存在的半導體特性。而在高濃度(x=0.2)摻雜下，樣品呈現出半金屬的行為。
第二部份為CeFe2Al10: 一般主要認為，f電子與傳導電子的交互作用，為稀土族化合物有著特殊物理性質的主要原因。近年來，CeFe2Al10也發現有著混和價數而引起研究上的興趣。而在f電子和傳導電子的作用下，往往會使得在費米面附近產生能隙，在我們NMR的研究結果中，認為在CeFe2Al10化合物中的能隙應歸為”贗能隙”而不是真正的能隙;這結果也和低溫比熱實驗結果一致。

As to measuring compounds such as magnetic susceptibility, specific heart, electrical resistivity, etc., these mainly focus on macroscopic behaviors for materials. It is generally believed that bulk property measurements usually fail to yield reliable estimations if impurity phases and/or defects appear in the samples. In order to avoid the influence of impurity in sample, we carry out nuclear magnetic resonance (NMR) technique to gain insight into the features of compounds. Because each atomic nucleus has its resonance absorption frequency, this reason allows us to choose appropriate atomic nuclei to detect and derive information about physical feature of the materials from analyzing experimental data. In this thesis, we report result of NMR study on two different semimetallic systems: CaxCo4Sb12 (x=0, 0.05, 0.13, and 0.2) and CeFe2Al10.
The first part is CaxCo4Sb12 (x=0, 0.05, 0.13, and 0.2): The host compound CoSb3 has great potential in thermoelectric property. It can reduce the thermal conductivity due to extra atoms in its voids, improving the thermoelectric performance further. In our NMR investigations, for low Ca (x≤0.13) concentrations our studied samples exhibit semiconducting characteristics with a trend of the reduction in the band gaps increasing the Ca content. For a higher Ca concentration (x=0.2), the NMR features can be described well in terms of a semimetallic response as the corresponding Fermi level falling within a pseudogap formed by nearby bands.
The second part is CeFe2Al10: Generally, the variously complicated and fascinating magnetic properties for the rare-earth based intermetals are due to the hybridization of the local f-electrons with conduction electrons. Recently, CeFe2Al10 compound also has the mixed-valence characteristic to be noted. However, an energy gap near Fermi level will often be produced by interaction between f-electron and conduction electrons. In our NMR results, the gap in CeFe2Al10 should be characterized as a pseudogap with a finite number of carriers at the Fermi level. This experimental result also consists with that of the low-temperature specific-heat measurement.

Content
           	page                               
中文摘要 	IV
Abstract 	V
誌謝 	VII
List of Figures 	VIII
List of Tables 	XIII
Chapter 1. Introduction	1
Chapter 2. The Principles of NMR In Solids	3
2-1. Zeeman effect	3   
2-2. Equations of motion	5
2-3. Spin Hamiltonian	9                                           
2-4. Knight Shifts	10
2-5. Spin-Lattice relaxation rates	14                                        
2-5-1. Introduce to Spin-Lattice relaxation rates	14                        
2-5-2. Formulas of Spin-lattice relaxation rates	15                         
2-5-3. Spin-Lattice relaxation rates for metals, semiconductors, and  
Semimetals	18                                               
I. Metals	18                                                   
II. Semiconductors	19                                           
III. Semimetals	20                                              
2-6. Electric quadrupole effect	24                                          
2-6-1. Introduce to quadrupole and electric field gradient (EFG)           24
2-6-2. Formulas of quadrupole effects	27                                
I. First-order quadrupole effect	28                                  
II. Second-order quadrupole effect	29                               
Chapter 3. Experimental Instruments And Techniques 	30          
3-1. NMR signal	30	            
3-2. Dewar flask	31                                        
3-3. Probe	34                                              
3-4. Temperature controller	36                                             
3-4-1. For temperature range from 77 K to 300 K	37                      
3-4-2. For temperature range from 4.2 K to 77 K	37                        
3-5. Measurements of T2 and T1	38                                        
3-5-1. Spin-echo technique	39                                        
3-5-2. Inverse and saturation comb techniques to measure T1	41               
I. Inversion Recovery	41                                         
II. Saturation Comb	44                                           
Chapter 4. Experimental Details And Discussion	45                
4-1. Evolution of the electronic structure in partially filled skutterudites:
CaxCo4Sb12	45                                                     
4-1-1. Introduction	45                                              
I. Skutterudite and filled-skutterudite structure	45                     
II. Motivation	48                                               
4-1-2. Sample Preparation	48                                         
I. The filling fraction limit	48                                     
II. Sample procedure	49                                          
III. The XRD patterns	50                                         
4-1-3. NMR measurement	52                                         
I. Powder pattern 	53                                            
A. Satellite lines	53                                         
B. Central patterns     	55                                  
II. Knight shifts	58                          
III. Spin-lattice relation rates	61                     
4-1-4. Discussion	68                                              
4-1-5. Conclusion	68                                                
4-2. 27Al NMR study of the hybridization gap in CeFe2Al10	70                   
4-2-1. Introduction	70                                            
I. General considerations of rare earth (RE) and 4f-electrons	70          
II. Introduction to hybridization gap (Kondo-insulator) and 
mixed valence	70                                          
III. Motivation	73                                              
4-2-2. Preparation for CeFe2Al10	75                                    
I. Sample procedure	75                                          
II. Each Al atomic coordinate in the YbFe2Al10-type structure	78         
4-2-3. NMR measurement	79                                         
I. Powder patterns	79                                            
A. Quadrupole interaction (  and  )	79                    
B. Sites identification	81                                     
C. Central transition ( )	82                         
II. Knight shifts	85                                              
III. Spin-lattice relation rates	92                                   
4-2-4. Conclusion	98                                                
Chapter 5. Summary	99                                               
References	101                                               
List of Publications	107

                                    

Reference

[1] G. S. Nolas, D. T. Morelli, and T. M. Tritt, Annu. Rev. Mater. Sci. 29, 89 (1991).
[2] W. Jeitschko and D. Braun, Acta Crystallogr. B33, 3401 (1977).
[3] F. Bloch, Phys. Rev. 70, 460 (1946).
[4] B. Bloembergen and T. J. Rowland, Acta. Met. 1, 731 (1953).
[5] C. H. Towenes, C. Herring, and W. D. Knight, Phys. Rev. 77, 852 (1950).
[6] R. Kubo and Y. J. Obata, J. Phys. Soc. Jpn. 11, 547 (1956).
[7] A. M. Clogston, V. Jaccarino and Y. Yafet, Phys. Rev. 134, A650 (1964).
[8] L. E. Orgel, J. Phys. Chem. Solids 21, 123 (1961).
[9] W. D. Knight, Phys Rev. 76 (1949) 1259.
[10] C. Kittel, Introduction to Solid State Physics, Eighth Edition, Chapter 11.
[11] J. D. Jackson. Classical Electrodynamic, third edition.
[12] DAS, T. P. and SONDHEIMER, E. H., Phil. Mag. 5, 529 (1960).
[13] STEPHEN, M. J., Proc. Phys. Soc. (Lond.) 79, 987 (1962).
[14] B. H. Bransden and C. J. Joachain, Introduction to Quantum Mechanics, Ch.9.
[15] Y. Obata, J. Phys. Soc. Jpn. 18, 1020 (1963).
[16] Y. Obata, J. Phys. Soc. Jpn. 19, 2348 (1964).
[17] Y. Yafet and V. Jaccarino, Phys. Rev. 133, A1630 (1964).
[18] A. Narath, Phys. Rev. 162, 320 (1967).
[19] T. Asada, K. Terakura, and T. Jarlborg, J. Phys. F 11, 1847 (1981).
[20] T. Asada and K. Terakura, J. Phys. F 12, 1387 (1982).
[21] B. Nowak, Solid State Nuclear magnetic Resonance 21, 53-60 (2002).
[22] H. Ebert, H. Winter, and J. Voitländer, J. Phys. F 14, 2433 (1984).
[23] J. Korringa, Physica 16, 601 (1950).
[24] W. H. Jones, Jr., T. P. Graham, and R. G. Barnes, Phys. Rev. 132, 1898 (1963).
[25] N. Bloembergen, E. M. Purcell, and R. V. Pound, Phys. Rev. 73, 679-746, (1948).
[26] E. L. Hahn, Phys. Rev. 80, 580, (1950).
[27] R. R. Ernst and W. A. Anderson, Application of Fourier Transform Spectroscopy to Magnetic Resonance Rev. Sci. Inst. 37, 93-102, (1966)
[28] J. W. Sharp, E. C. Jones, R. K. Williams, P. M. Martin, and B. C. Sales, J. Appl.
Phys. 78, 1013 (1995).
[29] B. C. Sales, D. Mandrus, R. K. Williams. Since 272, 1325 (1996).
[30] J. S. Dyck, W. Chen, C. Uher, L. Chen, X. Tang, and T. Hirai, J. Appl. Phys. 91,
3698 (2002).
[31] D. T. Morelli, G. P. Meisner, B. Chen, S. Hu, and C. Uher, Phys. Rev. B 56 7376
(1997).
[32] G. A. Slack, CRC Handbook of Thermoelectrics, edited by D. M. Rowe (Chemical Rubber, Boca Raton, FL, 1995), Chap. 34, p407.
[33] C. S. Lue, S. M. Huang, C. N. Kuo, F-T Huang and M-W Chu, New J. Phys. 10 083029 (2008).
[34] C. S. Lue, S. C. Chen, Phys. Rev. B 79 125108 (2009).
[35] M. Puyet, B. Lenoir, A. Dauscher, P. Pecheur, C. Belouard, J. tobola, and J. Hejtmanek, Phys. Rev. B 73, 035126 (2006).
[36] D. J. Singh and I. I. Mazin, Phys. Rev. B 56, R1650 (1997)
[37] G. P. Mesiner, D. T. Morelli, S. Hu, J. Yang, and C. Uher, Phys. Rev. Lett. 80 3551 (1998).
[38] L. Bertini and C. Gatti, J. Chem . Phys. 121, 8983 (2004).
[39] L. Chaput, P. Pecheur, J. Tobola, and H. Scherrer, Phys. Rev. B 72, 085126 (2005).
[40] K. Mangersnes, O. M. Lovvik, andO. Prytz, New J. Phys. 10, 053004 (2008).
[41] C. S. Lue, T. H. Su, B. X. Xie, and C. Cheng, Phys. Rev. B 74 094101 (2006).
[42] Lidong Chen, 21st International Conference on Thermoelectronics (2002).
[43] M. Puyet, B. Lenoir, A. Dauscher, P. Weisbecker, and S. J. Clarke, Journal of Solid State Chemistry 177, 2138-2143 (2004).
[44] C. S. Lue, Y. T. Lin, and C. N. Kuo, Phys. Rev. B 75, 075113 (2007).
[45] A. R. Denton and N.W. Ashcroft, Phys. Rev. A 43, 3161 (1991).
[46] M. H. Cohen and F. Reif , in Solid State Physics, edited by f. Seitz and D.
Turnbull (Academic, New York, 1957), Vol. 5, p.311.
[47] Metallic shifts in NMR, edited by G. C. Cater, L. H. Bennett, and D. J. Kahan (Pergamon, Oxford, 1977).
[48] M. Puyet, B. Lenoir, A. Dauscher, P. Pécheur, C. Bellouard, J. Tobola, and J. Hejtmanek, Phys. Rev. B 73, 035126 (2006).
[49] C. S. Lue and Joseph H. Ross, Jr, Phys. Rev. B 58, 9763 (1998).
[50] C. S. Lue and Joseph H. Ross, Jr, Phys. Rev. B 63, 054420 (2001).
[51] N. Albert, Phys. Rev. 162 320 (1967).
[52] N. Bloembergen, Physica (Amsterdam) 20 1130 (1954); Dieter Wolf, Spin Temperature and Nuclear-spin Relaxation in Matter (Clarendon, Oxford, 1979).
[53] K. Yoshimura, M. Mekata, M. Takigawa, Y. Takahashi, and H. Yasuoka, Phys. Rev. B 37, 3593 (1988).
[54] G. Aeppli and Z. Fisk, Comments Condens. Matter Phys. 16, 155 (1992) and
references therein.
[55] P. S. Riseborough, Adv. Phys. 49, 257 (2000) and references therein.
[56] Z. Fisk, J. L. Sarrao, J. D. Thompson, D. Mandrus, M. F. Hundley, A. Miglori, B. Bucher, Z. Schlesinger, G. Aeppli, E. Bucher, J. F. DiTusa, C. S. Oglesby, H-r. Ott, P. C. Canfield, and S. E. Brown, Physica B 206-207, 798 (1995).
[57] M. Takigawa, H. Yasuoka, Y. Kitaoka, T. Tanaka, H. Nozaki, and Y. Ishizawa, J. Phys. Soc. Jpn. 50, 2525-2532 (1981).
[58] J. W. Allen, B. Batlogg, and P. Wachter, Phys. Rev. B 20,4807 (1979).
[59] M. Kasaya, F. Iga, K. Negishi, S. Nakai, and T. Kasuya, J. Magn. Magn. Mater. 31-34, 437 (1983).
[60] M. F. Hundley, P. C. Canfield, J. D. Thompson, Z. Fisk, and J. M. Lawrence, Phys. Rev. B 42, 6842 (1990).
[61] T. Takabatake, F. Teshima, H. Fujii, S. Nishigori, T. Suzuki, T. Fujita, Y. Yamaguchi, J. Sakurai, and D. Jaccard, Phys. Rev. B 41, 9607 (1990).
[62] R. A. Neifeld, M. Croft, T. Mihalisin, C. U. Segre, M. Madigan, M. S. Torikachvili, M. B. Maple, and L. E. DeLong, Phys. Rev. B 32, 6928 (1985).
[63] M. Croft, R. Neifeld, C. U. Segre, S. Raacn, and R.D. Parks, Phys. Rev. B 30, 4164 (1984).
[64] Y. Muro. M. Motoya. Y. Saiga, and T. Takabatake, J. Phys. Soc. Jpn. 78, 083707 (2009).
[65] C. S. Lue and J. H. Ross, Jr., Phys. Rev. B 58, 9763 (1998)
[66] C. S. Lue , C. F. Chen, F. K . Chiang, and M. W. Chu, Phys. Rev. B 80, 174202 (2009).
[67] S. Niemann and W. Jeitschko, Z. Kristallogr. 210, 338 (1995).
[68] V. M. T. Thiede, T. Ebel, and W. Jeitschko, J. Master. Chem. 8, 125 (1998).
[69] T. Nishioka, Y. Kawamura, T. Takesaka, R. Kobayashi, H. kato, M. Matsumura. K. Kodama, K. Matsubayashi, and Y. Uwatoko, J. Phys. Soc. Jpn. 78, 123705 (2009).
[70] M. E. Smith, appl. Magn. Reson. 4, 1 (1993).
[71] C. S. Lue, T. H. Su, B. X. Xie, S. K. Chen, J. L. Macmanus-Driscoll, Y. K. Kuo, and H. D. Yang, Phys. Rev. B 73, 214505 (2006).
[72] C. S. Lue, S. C. Chen, Phys. Rev. B 79, 125108 (2009).
[73] M. Matsumura, Y. Kawamura, S. Edamoto, T. Takesaka, H. Kato, T. Nishioka, Y. Tokunagai, S. Kambei, and H. Yasuokai, J. Phys. Soc. Jpn. 78, 123713 (2009).
[74] A. M. Clogston, V. Jaccarino, and Y. Yafet, Phys. Rev. 134, A650 (1964).
[75] V. Jaccarino, G. K . Wertheim, J. H. Wernick, L. R. Walker, and S. Arajs, Phys. Rev. 160, 476 (1967).
[76] M. Takigawa, H. Yasuoka, Y. Kitaoka, T. Tanaka, H. Nozaki, and Y. Ishizawa, J. Phys. Soc. Jpn. 50, No.8, 2525 (1981).
[77] C. Petrovic, Y. Lee, T. Vogt, N. Dj. Lazarov, S. L. Bud’so, and P. C. Canfield, Phys. B 72, 045103 (2005).
[78] T. Takesaka, K. Oe, R. Kobayashi, Y. Kawamura, T. Nishioka, H. Kato, M. Matsumura, and K. Kodama, J. Phys.: Conf. Ser. 200, 012201 (2010)
[79] R. E. J. Sears, Phys. Rev. B 22, 1135 (1980).
[80] C. S. Lue, B. X. Xie, S. N. Horng, J. H. Su, and J. Y. Lin, Phys. Rev. B 71, 195104 (2005).
[81] Y. Kawasaki, M. Izumi, y. Kishimoto, T. Ohno, H. Tou, Y. Inaoka, M. Sera, K. Shigetoh, and T. Takabatake, Phys. Rev. B 75, 094410 (2007).
[82] N. Albert, Phys. Rev. 162 320 (1967).
[83] T, Caldwell, A. P. Reyes. W. G. Moulton, P. L. Kuhns, M. J. R. Hoch, P. Schlottmann, and Z. Fisk, Phys. Rev. B 75, 075106 (2007).
[84] M. Kasaya, F. Iga, M. Takigawa, and T. Kasuya, J. Magn, Magn. Mater. 47-48, 429 (1985).
[85] R. Sarkar, K. Ghoshray, B. Bandyopadhyay, and A. Ghoshray, Phys. Rev. B 71, 104421 (2005).
[86] A. P. Reyes, R. H. Heffner, P. C. Canfield, J. D. Thompson, and Z. Fisk, Phys. Rev. B 49 16321 (1994).
[87] E. M. Bruning, M. Baenitz, A. A. Gippius, A. M. Strydom, F. Steglich, and R. E. Walstedt, J. Magn. Magn. Mater. 310, 393 (2007).
[88] K.-i. Nakamura, Y. Kitaoka, K. Asayama, T. Takabatake, G. Nakamoto, H. Tanaka, and H. Fujii, Phys. Rev. B 53, 6385 (1996).
[89] A. K. Rajarajan, A. Rabis, M. Baenitz, A. A. Gippius, E. N. Morozowa, J. A. Mydosh, and F. Steglich, Phys. Rev. B 76, 024424 (2007).
[90] A. A. Gippius, M. Baenitz, A. K. Rajarajan, E. M. Bruening, K. Okhotnikov, R. Walstedt, A.Strydom, J. Mydosh, and F. Steglich, J. Phys.: Conf. Ser. 150, 042040 (2009).

校內：2012-08-01公開
校外：2012-08-01公開

簡易檢索 / 詳目顯示

相關論文