| 摘要(英) |
Most substances will thermally expand with increasing temperature, but the phenomenon of negative thermal expansion of substances, the so-called thermal contraction, is not uncommon. This phenomenon is mostly caused by anisotropic structures, and the thermal contraction of isotropic structures is often accompanied by structural change. The most widely known thermal contraction is the thermal contraction of liquid water below 4°C, which is also due to the change in the bond angle of water molecules. In the 2002 paper of this laboratory, the thermal contraction of 4 nm gold nanoparticles was also found [1], which was explained by the quantum scale effect. Later, the Professor Chun-Chuen Yang also discovered the thermal contraction of silver nanoparticles in the 2006 experiment.
In this thesis, the temperature define X-ray diffraction data made by Professor Chun-Chuen Yang will be used for lattice constant and electron distribution analysis. First, we found that the thermal contraction at 10 to 60 K in Ag NPs with a particle size as small as 5 nm, and the abnormal thermal expansion in both 5 nm and 9 nm samples . In the second half of the thesis, I calculated the changes of the electron distribution to observe the corresponding changes when thermal contraction happened, and found that 5 nm Ag NPs transfer electrons to the outer layer when thermal contraction happened then returns to the inner layer of the Ag ion after thermal expansion. |
| 參考文獻 |
[1] W.-H. Li, S.Y.Wu, C. C. Yang, S. K. Lai, K.C.Lee, H. L. Huang and H. D. Yang, ”Thermal Contraction of Au Nanoparticles” Phys.Rev.Lett 89.135504, 2002
[2] N. N. Greenwood, A. Earnshaw, ”Chemistry of the Elements” 2012, p.1173–1174
[3] Serenella Medici, Massimiliano Peana, Valeria M. Nurchi, and Maria Antonietta Zoroddu, ” Medical Uses of Silver: History, Myths, and Scientific Evidence” J. Med. Chem. 2019, 62, 13, p.5923–5943
[4] Juris Meija,et al., ”Atomic weights of the elements 2013” Pure Appl. Chem. 2016, 88(3), p.265–291
[5] 林元媛：〈粒徑大小對奈米銀自發磁性之影響〉碩士論文，國立中央大學，民國102年6月
[6] Alan Russell, Kok Loong Lee, ”Structure-property relations in nonferrous metals” , 2005, p.321
[7] Wen-Hsien Li and Chi-Hung Lee, ”Spin Polarization and Small Size Effect in Bare Silver Nanoparticles” Complex Magnetic Nanostructures, 2017, p.195–225
[8] 蘇志杰：〈奈米粉粒的熱縮現象〉，碩士論文，國立中央大學，民國92年6月
[9] 楊仲準，X 光繞射分析技術與應用，科儀新知第三十二卷第六期，民國100年6月，64–72頁
[10] BL01C2 - Powder and Fiber X-ray Diffraction Technical Information，取自：http://efd.nsrrc.org.tw/EFD.php?num=237
[11] H. M. Rietveld, ” J. Appl. Cryst.” 1969, p.65–71
[12] 許樹恩、吳泰伯，X光繞射原理與材料結構分析，國科會精儀中心，民國82年
[13] 戴士傑：〈磷摻雜對鐵基超導材料LaOFeAs1-xPx中電子分佈的影響〉碩士論文，國立中央大學，民國106年6月 |
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