簡易檢索 / 詳目顯示

回結果列表
研究生： 宋明遠
Song, M.Y
論文名稱： Fe2VAl摻雜Nb及Ta之熱電性質之研究
Study of Nb and Ta substitution on the thermoelectric properties of Fe2VAl
指導教授： 呂欽山
Lue, C.S
學位類別： 碩士
Master
系所名稱： 理學院 - 物理學系
Department of Physics
論文出版年： 2008
畢業學年度： 96
語文別： 英文
論文頁數： 43
中文關鍵詞： 熱電
外文關鍵詞： Fe2VAl
相關次數： 點閱：64  下載：2 
分享至:
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

    • Fe2VAl在過去的研究中，因為他多變的特性而引起許多學者的廣泛討論，在過去的研究中指出Fe2VAl是一個Heusler-type的半金屬2-5，在我們研究的熱電材料中，半金屬具有較高的熱電優質。在這次的研究結果中，我們列出了掺雜Nb或Ta的Fe2VAl的熱電性質的實驗結果，其中包括電阻率、熱導率、Seebeck coefficient以及熱電優值(Figure-of-merit)，在這次的實驗中，我們將Nb以及Ta掺雜而取代Fe2VAl中的V的位置，這樣的替代結果造成晶格的無序度增加，進而大大的降低了樣品的熱導率，此外，因為替代的原子序較高，造成樣品的能帶結構發生改變，包括了能帶的形態和能隙，這樣的結果由Seebeck coefficient的量測結果可以得知，掺雜會造成能隙變小，由於掺雜後的樣品，同時伴隨了Seebek coefficient的增加以及熱導率的減少，根據 可以得到一個簡單的結論，掺雜可以有效的提高樣品的熱電優質。

    Fe2VAl have attracted great interests due to their various physical behavior, including excellent thermoelectric performance. It has been reported as a Heusler-type2-5 semimetal compound and we focus on the thermoelectric properties of semiconductinglike materials for their high ZT value (figure-of-merit). We report the results of thermoelectric experiment of Fe2VAl substituted by Nb and Ta on V site. The experimental results include electrical resistivity, thermal conductivity, Seebeck coefficient as well as figure-of-merit. The results show that substitution causes a remarkable reduction of thermal conductivity and also changes the band structure accompany the decrease in the width of energy gap. The result can be associated with chemical disorder results from Nb and Ta substitution on V site.

    Contents 摘要 1 Abstract 2 Chapter 1 Introduction 3 Chapter 2 Sample preparation 6 Chapter 3 Basic Concepts 9 3-1 Electrical Conductivity 10 3-2 Thermal Conductivity 12 3-3 Umklapp Scattering 15 3-4 Wiedemann-Franz Law and Callaway Model 17 3-5 Seebeck Effect 19 3-6 Figure-of-merit 21 Chapter 4 Results and Discussion 23 4-1 Electrical conductivity 23 4-2 Thermal conductivity 26 4-3 Seebeck coefficient 36 4-4 Figure of merit 39 Chapter 5 Conclusions 42 Reference 43 List of Figures Fig. 1-1 Cubic L21 lattice of Fe2VAl 4 Fig. 1-2 (a) Full band-structure calculation of Fe2VAl by Weht4 and (b) Density of states of Fe2VAl 5 Fig.2-1 Schema of Arc-melting furnace 6 Fig. 2-2 Power X-Ray diffraction patterns 7 Fig. 2-3 Lattice parameter vs Nb and Ta concentration 8 Fig.3-1 (a) Normal-Process (b) Umklapp-Process 16 Fig.3-2 Seebecke ffect 19 Fig.3-3 Thermoelectric generator (Seebeck) 21 Fig.3-4 Refrigerator 21 Fig.4-1 Resistivity as a function of temperature for Fe2V1-xNbxAl 24 Fig.4-2 Resistivity as a function of temperature for Fe2V1-xTaxAl 25 Fig.4-3 Thermal conductivity versus temperature for Fe2V1-xNbxAl 27 Fig.4-4 Thermal conductivity versus temperature for Fe2V1-xTaxAl 28 Fig.4-6 Fitting curves and experimental results for Fe2V1-xNbxAl 34 Fig.4-7 Fitting curves and experimental results for Fe2V1-xTaxAl 35 Fig.4-8 Seebeck coefficient vs temperature for Fe2V1-xNbxAl 37 Fig.4-9 Seebeck coefficient vs temperature for Fe2V1-xTaxAl 38 Fig.4-10 ZT value as a function of temperature for Fe2V1-xNbxAl 40 Fig.4-11 ZT value as a function of temperature for Fe2V1-xTaxAl 41 List of Tables Table 4-1 Parameters of fitting curves for Fe2V1-xNbxAl 31 Table 4-2 Parameters of fitting curves for Fe2V1-xTaxAl 32

    1. D.M. Rowe, Thermoelectric Handbook Macro to Nano (2006)
    2. D.J. Singh and I.I. Mazin, Phys. Rev. B 57,14352 (1998)
    3. C. S. Lue and Joseph H. Ross, Jr. Phys. Rev. B 61,9863 (2000)
    4. Ruben Weht and W. E. Pickett Rev. B 58,6855 (1998)
    5. C. S. Lue and Joseph H. Ross, Jr. Phys. Rev. B 58,9763 (1998)
    6. M. Weinert and R. E. Watson Phys. Rev. B 58,9732 (1998)
    7. H. Okamura et al., Phys. Rev. L 84, 3674 (1999)
    8. L.-S. Hsu, Y.-K. Wang, G. Y. Guo and C. S. Lue Phys. Rev. B
    66,205203 (1998)
    9. I. Galanakis and Dederichs Phys. Rev. B 66,174429 (1998)
    10. Charles Kittel Introduction to Solid State Physics
    11. Callaway Phys. Rev. B 113,1046 (1958)
    12. Callaway and Baeyer Phys. Rev. B 120,1149 (1960)
    13. Callaway Phys. Rev. B 122,787 (1960)
    14. G.S. Nolas, J. Sharp and H.J. Goldsmid Thermoelectrics
    15. N.F. Mott and H. Jones The theory of the properties of metals and
    alloys
    16. Y. Nishino et al., Phys. Rev. L 79,1909 (1997)
    17. C. S. Lue, C. F. Chen, J. Y. Lin Phys. Rev. B 75,064204 (2007)
    18. C. S. Lue and Y.-K. Kuo Phys. Rev. B 66,085121 (2002)
    19. K. Gofryk et al., Phys. Rev. B 75, 224426 (2007)
    20. Y. Nishino et al., Phys. Rev. B 63, 233303 (2001)
    21. C S Lue, W J Lai, C CChen and Y-K Kuo, J. Phys.: Condens. Matter
    16 4283(2004)

    下載圖示 校內：立即公開
    校外：2008-07-16公開
    QR CODE