Nanoparticles of Co-doped Y2O3, as well as their core-shell composites with Co-doped core and Y2O3 shell, were prepared by ployol method. Thermal annealing at different temperatures from 300OC to 1050OC was employed to control the particle size within the range of 5 nm to 134 nm in diameter. The host crystal structures were investigated by x-ray powder diffraction (XRD) and high-resolution transmission electron microscope (HR-TEM).
Local environments surrounding Y and Co in these materials were probed by using extended x-ray absorption fine structure (EXAFS) techniques. Our x - ray results reveal that the Co impurity atoms interstitial adajacent O sites in the Y2O3 host with smaller Co-O distance compared to that of the Y-O bond. As indicated by the appreciably reduced coordination number of the nearest O shell around the central Co atom, a large percentage of Co atoms may be located on the particle surface. However, the number of surface Co atoms was found to be great reduced in the core-shell samples. Co-doped Y2O3 Nanoparticle magnetic moment and Thermo-remanent were measured by superconducting quantum interference device magnetometer(SQUID). All of samples perform phase supercomposition of paramagnetic and ferromagnetic at room temperature. The carrier-mediated of magnetic ions in high-k material which has no free electron insides can be explained by bound magnetic polaron theory and percolation theory . Cation local structure and oxygen vacancies play an important role in promoting BMP theory.Most of Co Ions play paramagnetic state and proportion to number of oxygen vacancies.

以聚酯多元醇法製備三氧化二釔摻雜鈷離子奈米粒子和摻雜鈷離子的中心與純三氧化二釔殼層組合。利用熱鍛燒不同溫度約00OC到 1050OC的方式控制奈米粒子直徑範圍約5 nm 到134 nm使用X光粉末反射式繞射儀與高解析穿透式電子顯微鏡研究主體晶體結構特性。發現主體為穩定方鐵錳礦晶型。
使用邊緣延伸X光吸收精細結構量測技術探測分析釔和鈷原子在主體內的局域結構。X光分析結果顯示鈷原子鑲嵌在主體內鄰近氧的位置且鈷氧鍵結距離比主體釔氧鍵結距離短上許多。除此之外還量出配位數有可觀的下降顯示大部分的鈷離子可能聚集在表面雖然EDX image結果沒有發現這樣的結果。然而在殼層系列的樣品發現表面鈷離子大量減少。三氧化二釔摻雜鈷離子奈米粒子的磁矩與隨溫度改變的殘磁場使用超導量子干涉元件量測。所有的奈米粒子樣品在室溫下呈現鐵磁相與順磁相的二相疊加。沒有任何的自由電子在其中的高介電係數物質內部的傳導載子可以用bound magnetic polarons (BMPs) 理論與滲透理論解釋。陽離子局域結構與氧空缺在其中扮演了很重要的角色。樣品內的鈷離子大部分處於順磁態且與氧空缺的數目呈線性相關。

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