氧化亞銅與氧化銅奈米微粒的熱縮現象探討; The phenomenon of thermal contraction of cuprous oxide and cupric oxide nanoparticles

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题名:	氧化亞銅與氧化銅奈米微粒的熱縮現象探討;The phenomenon of thermal contraction of cuprous oxide and cupric oxide nanoparticles
作者:	林聖達;Sheng-da Lin
贡献者:	物理研究所
关键词:	熱縮現象;電荷密度;自旋波;塞曼效應;自旋極化;spin polarzation;Zeeman effect;spin wave;charge density;thermal contraction
日期:	2011-07-13
上传时间:	2012-01-05 14:41:38 (UTC+8)
摘要:	本實驗室是用低真空熱蒸鍍法製成銅奈米微粒，在缺氧環境下氧化成氧化亞銅、以及在大氣中繼續氧化為氧化銅，經由X光繞射實驗與結構精算軟體得知樣品詳細成分和晶體結構，知道氧化亞銅與氧化銅粒徑各為5.5 nm及3.6 nm。利用物理特性量測系統測量氧化亞銅及氧化銅在不同溫度下的磁化曲線，並利用朗之萬函數、布里淵函數、反磁項進行擬合。在低溫下主要是自旋極化與塞曼效應對氧化亞銅的磁化強度貢獻，而在高溫中則是自旋極化與反磁項對磁化強度的貢獻。氧化銅在低溫有兩個分量做主導，自旋極化與塞曼效應，隨溫度增加塞曼效應貢獻會趨近於零，然而磁化強度卻隨磁場增加而變強，顯示氧化銅有其他機制的貢獻。氧化亞銅和氧化銅的Ms(T)以及M(T)曲線圖利用布洛赫定律擬合，由擬合結果顯示奈米微粒系統具有自旋波的存在。對氧化亞銅奈米微粒作變溫X-Ray，顯示氧化亞銅在150~180 K有熱收縮現象，將晶格常數變化與奈米微粒磁性作比較，發現飽和磁化強度對溫度變化和晶格常數對溫度變化很像，推測電荷重新分佈對晶格常數有所影響，因此藉由氧化亞銅電荷密度分佈，發現晶格結構某些位置的電荷密度隨溫度變化趨勢與晶格常數隨溫度變化趨勢很像，說明電荷重新分佈與晶格常數是有關聯。 The copper nanoparticles were manufactured by the thermal evaporation method. We got the sample of cuprous oxide from a process that heated the copper in a condition in which not enough oxygen, and got the sample of cupric oxide from the process that heated in air. The chemical composition of the sample were pure Cu2O and CuO by X-ray diffraction and General Structure Analysis System. The mean particle diameter of Cu2O and CuO nanoparticles were 5.5 nm and 3.6 nm that determined respectively by X-ray diffraction patterns. Magnetic properties of nanoparticles were measured by Physical Property Measurement System. The M(H) of Cu2O in various temperature were observed, then fitted the M(H) curve by a Langevin function, a Brillouin function and a diamagnetic term. From a result of fitting curve at all temperature, there were three effect in the system, spin polarization, Zeeman effect, diamagnetic term. At low temperature, the M(H) of Cu2O could be represented by spin polarization and Zeeman effect, then at high temperature, M(H) could be predominated by spin polarization and diamagnetic term. Looking the M(H) curve of CuO, it showed there were two components in the system at low temperature, spin polarization and Zeeman effect. M(H) was risen with magnetic field increasing at high temperature, there was other term in the system. By fitting Ms(T) and M(T),we observed that it had spin wave in the nanoparticle system. By the XRD patterns, we observed that Cu2O had a property of the negative thermal expansion at 150~180 K, and it had a relation with charge density transition.
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