氧化亞銅奈米顆粒的熱縮現象探討; Thermal contraction behavior of cuprous oxide nanoparticles

Please use this identifier to cite or link to this item: http://ir.lib.ncu.edu.tw/handle/987654321/7622

Title:	氧化亞銅奈米顆粒的熱縮現象探討;Thermal contraction behavior of cuprous oxide nanoparticles
Authors:	吳政道;Cheng Tao Wu
Contributors:	物理研究所
Keywords:	自旋極化;奈米粒子;負熱膨漲;氧化亞銅;spin polarization;nanoparticle;negative thermal expansion;cuprous oxide
Date:	2009-06-22
Issue Date:	2009-09-22 11:00:59 (UTC+8)
Publisher:	國立中央大學圖書館
Abstract:	使用低真空熱蒸鍍系統製作銅奈米顆粒，並將其放置於自然大氣氧化八個月後得到樣品Cu071227。利用X光繞射實驗與能量散佈光譜得到樣品由氧與銅原素構成且樣品的化學式為Cu2O0.88。借由掃描式電子顯微鏡與積分寬法和共同體積函數計算X光繞射譜圖得到樣品的粒徑為14.3nm。利用在不同實驗溫度下所得之X光繞射譜圖計算樣品晶格參數隨溫度的變化，推測氧化亞銅奈米顆粒在190至230 K晶格常數有熱縮的現象。對樣品進行在不同實驗溫度下之拉曼散射實驗並以勞侖茲函數擬合峰值，觀察氧化亞銅的拉曼振動模式溫度峰值位置的變化在190至230 K溫度區間隨著溫度昇高有移向高拉曼位移的趨勢，推測原因為氧化亞銅奈米顆粒在晶格常數熱縮的溫度區間銅離子間距離縮短，造成只有銅離子振動的拉曼振動模式之拉曼位移受到影響。使用物理特性量測系統量測氧化亞銅奈米顆粒在不同實驗溫度下的磁化曲線並使用朗之萬函數加反磁線性項擬合之，可以觀察在210至230 K溫度區間磁矩隨溫度增加而急遽上升，而230至280 K溫度區間磁矩又隨溫度的增加而降低，推測氧化亞銅晶格的熱縮現象也會造成顆粒磁矩的變化。 The sample Cu071227 was formed by natural oxidation of Cu nanoparticles for eight months, which are fabricated by the thermal evaporation method. X-ray diffraction and energy dispersive spectrometer indicate that the chemical composition of sample is Cu2O0.88. The mean particle diameter is 14.3nm determined using scanning electron microscopy image and X-ray diffraction patterns. Temperature dependence of the X-ray diffraction patterns are measured to study the thermal evolution of lattice parameters. The results reveal a negative thermal expansion in the temperature region of 190 to 230 K. We perform the Raman scattering experiment at selective temperature and used Lorentzian functions to fit the Raman spectra. The Raman shift of the phonon mode (out-of-phase in-plane vibrations of Cu) increases with increasing temperature region of 190 to 230 K. The phenomenon may be understood by the reduction of the distance between Cu ions in that temperature region. Magnetic properties were studied by Physical Property Measurement System. The M-H curve of the cuprous oxide nanoparticles can be described by a Langevin function plus a diamagnetic term. The mean particle moment rapidly increases in the temperature region of 210 to 230 K, followed by progressing decreases between 230-280 K. This indicates the change in particle moment and the thermal contraction behavior of cuprous oxide nanoparticle are indeed related.
Appears in Collections:	[Graduate Institute of Physics] Electronic Thesis & Dissertation

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