臺灣博碩士論文加值系統

在具有磁性的化合物中，當樣品接近奈米（nanometer）尺寸時，超微粒（nanoparticles）顆粒大小會導致磁性的變化。重費米（heavy fermion）系統內有少數的超導化合物，CeCo2超微粒即為其中之一。CeCo2 塊材與超微粒樣品擁有許多不同的物理性質。CeCo2的塊材是個Tc=0.9∼1.5K的 Pauli順磁性超導體；然而，CeCo2的超微粒擁有比較複雜的磁性與超導性。 CeCo2超微粒的比熱在 0.5∼1K有異常的現象發生，其電子熱容量γ=350mJ/mol K2明顯的增加可能是原超導性受到壓制所造成。CeCo2超微粒的磁性在 T>200K是呈現「超順磁」，在低溫 10∼30K 則是呈現「自旋玻璃」的現象。

It was known that the magnetic properties were influenced by the size of specimens in some Ce-based compounds as the size approaches to nanometer scale. There are a few of superconducting compounds in heavy fermion system. In this study, the difference of magnetic properties and superconductivity in CeCo2 bulk and nanoparticles specimens is reported. CeCo2 bulk is a Tc=0.9~1.5K superconducting compound with Pauli paramagnetism, whereas CeCo2 nanoparticles exhibit more complex magnetic properties and superconductivity. In specific heat of CeCo2 nanoparticles, an anomaly at T=0.5~1K was observed. This is conjectured to be an incomplete suppression of superconductivity. The linear coefficient of heat capacity γ=350 mJ/mole‧K2 of nanoparticles is extraordinarily larger than that of bulk. A superparamagnetic behavior was shown at T＞200K and a low-temperature
spin-glass-like behavior was observed at T＝10~30K.

目錄．．．．．．．．．．．．．．．．．．．．．．．．．．． Ⅰ
論文摘要（中文）．．．．．．．．．．．．．．．．．．．．． Ⅲ
Abstract．．．．．．．．．．．．．．．．．．．．．．．．． Ⅳ
誌謝．．．．．．．．．．．．．．．．．．．．．．．．．． Ⅴ
第一章 簡介．．．．．．．．．．．．．．．．．．．．．． 1
§1-1 超微粒子簡介．．．．．．．．．．．．．．．．．．． 1
§1-2 稀土族元素與重費米化合物．．．．．．．．．．．．． 2
第二章 樣品的製作．．．．．．．．．．．．．．．．．．．． 5
§2-1 塊材的製作(弧光放電原理)．．．．．．．．．．．．． 5
§2-2 超微粒的製作．．．．．．．．．．．．．．．．．．． 7
熱蒸鍍原理(電阻加熱法) ．．．．．．．．．．．．． 7
第三章 量測儀器與相關理論．．．．．．．．．．．．．．． 14
§3-1 比熱原理．．．．．．．．．．．．．．．．．．．．． 14
§3-2 比熱儀器介紹．．．．．．．．．．．．．．．．．．． 22
§3-3 低溫3Hｅ系統降溫程序．．．．．．．．．．．．．．． 30
§3-4 超導量子干涉磁量儀(SQUID)之原理．．．．．．．．． 32
第四章 實驗結果與分析．．．．．．．．．．．．．．．．． 36
§4-1 X-ray與HRTEM．．．．．．．．．．．．．．．．．． 36
§4-1-1 X-ray繞射分析．．．．．．．．．．．．．．．．．． 36
§4-1-2 HRTEM粒徑分析．．．．．．．．．．．．．．．． 37
§4-2 比熱數據分析．．．．．．．．．．．．．．．．．．． 39
§4-2-1 CeCo2塊材的比熱分析．．．．．．．．．．．．．． 39
§4-2-2 CeCo2超微粒與塊材的比熱綜合分析．．．．．．．． 41
§4-2-3 CeCo2超微粒加磁場的比熱分析．．．．．．．．．． 44
§4-3 磁性數據分析．．．．．．．．．．．．．．．．．．． 46
§4-3-1 CeCo2塊材磁性分析．．．．．．．．．．．．．．． 46
§4-3-2 CeCo2超微粒磁性分析．．．．．．．．．．．．．． 49
A、CeCo2超微粒的超順磁．．．．．．．．．．．．．． 50
B、CeCo2超微粒的自旋玻璃．．．．．．．．．．．．．． 53
C、CeCo2超微粒的磁性來源．．．．．．．．．．．．．． 55
D、CeCo2超微粒的晶場分裂效應．．．．．．．．．．． 56
第五章總結．．．．．．．．．．．．．．．．．．．．．． 57
§5-1 CeCo2塊材的物理特性．．．．．．．．．．．．．．．． 57
§5-2 CeCo2超微粒的物理特性．．．．．．．．．．．．．．． 58
參考文獻．．．．．．．．．．．．．．．．．．．．．．．． 59

【1】Solid state physics[by] Neil W. Ashcroft [and] N. David Mermin./ New York,Holt, Rinehart and Winston/[c1976]/
【2】Solid state physics[by] Seitz, Frederick,1911-/ Turnbull, David,1915-/ New York,Academic Press,/1955-/
【3】Introduction to solid state physics /Charles Kittel./ New York :Wiley,/c1986./
【4】Ferromagnetic materials :a handbook on the properties of magnetically ordered substances //edited by E. P. Wohlfarth./ 1980 （p.334－356）
【5】Spin glasses /K.H. Fischer, J.A. Hertz./ Cambridge ;New York, NY, USA :Cambridge University Press,/1991./
【6】Introduction to magnetism and magnetic materials /David Jiles./ London ;New York :Chapman and Hall,/1991./
【7】Introduction to magnetic materials[by] B. D. Cullity./ Reading, Mass.,Addison-Wesley Pub. Co./[1972]/
【8】低溫物理學/曹烈兆等編著－合肥：中國科學技術大學出版社，1999
【9】磁性物理學/ [宛德福、馬興隆] 電子科技大學出版社
【10】磁性玻璃/ [王陽君、李國棟…等 譯] 科學出版社，1992
【11】Structure, Crystal Fields, Magnetic Interaction and Heavy Fermion Behavior in (Ce1-xLax)3Al/ Physical Review B Vol.55 , (1997)/pp.5937-5943/ Y.Y. Chen, Y.D. Yao, B.C. Hu, C.H. Jang,J.M. Lawrence, H.Huang and W.H. Li
【12】Magnetic behaviour of CeCo2 /Physica B Vol. 269, (1999)/ pp. 362-367/Seixas, T.M.; Machado da Silva, J.M.
【13】Anisotropic superconducting gap in CeCo2 - Specific heat studies /Physica B Vol.237-238,(1997) /pp.302-303/Y. Aoki, T. Nishigaki, H. Sugawara, H. Sato
【14】Tranport properties in CeCo2 single crystal / Physica B Vol.230-232,(1997) /pp.179-181/ H. Sugawara, T. Nishigaki, , Y. Kobayashi, Y. Aoki, H. Sato
【15】Mixed state transport properties and peak effect in f-electron superconductors /Physica B Vol.230-232,(1997) /pp.402-405/ H. Sato, Y. Aoki, Y. Kobayashi , H. Sugawara, T. Nishigaki, et.
【16】Transport properties of RECo2 compounds (RE＝Tb, Dy, Ho, Er, Y) /J. Phys. F: Metal Phys. Vol.11,(1981)/pp.429-35 / H. Sugawara, T. Nishigaki, , Y. Kobayashi, Y. Aoki, H. Sato
【17】Magnetic and transport properties of (La,Ce)Ni2 /Physical Review B Vol.41,(1990) /pp.2307-2312/A. Mauger, V. Paul-Boncour, M. Escorne, et.
【18】Superconductivity and magnetic order in CeCo2 /MMM Vol.140-144, (1995) /pp.2057-2058/J.-G. Park, M. Ellerby, K.A. McEwen, M. de Podesta
【19】Superconductiing Properties and de Haas-van Alphen Effect in CeCo2 Single Crystal /JPJ Vol.64, (1995) /pp.3639-3642/
【20】Fermi surface properties in CeCo2 /JPJ Vol.65, (1996 )/pp.1744-1750/M. Higuchi, Y. Onuki, A. Hasegawa
【21】Paramagnetism, superparamagnetism, and spin-glass behavior in bulk amorphous Pd-Ni-Fe-P alloys ./J Applied Physics, Vol. 85, (1999) /pp.4110-4119/