Microwave-Assisted Nonaqueous Sol鈭扜el Chemistry for Highly Concentrated ZnO-Based Magnetic Semiconductor Nanocrystals

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• 作者：Idalia Bilecka ; Li Luo ; Igor Djerdj ; Marta D. Rossell ; Marko Jagodic虒 ; Zvonko Jaglic虒ic虂 ; Yuji Masubuchi ; Shinichi Kikkawa ; Markus Niederberger
• 刊名：Journal of Physical Chemistry C
• 出版年：2011
• 出版时间：February 10, 2011
• 年：2011
• 卷：115
• 期：5
• 页码：1484-1495
• 全文大小：1251K
• 年卷期：v.115,no.5(February 10, 2011)
• ISSN：1932-7455

文摘

Various transition metal (TM) doped zinc oxide nanoparticles with the composition TM_xZn_1鈭?i>xO (TM = V, Mn, Fe, Co, and Ni; x = 0.01鈭?.3) were prepared by a microwave-assisted nonaqueous sol鈭抔el route in benzyl alcohol within a few minutes. The high doping levels in the range 20鈭?0 atom % achieved for Co and Fe provide a promising opportunity to study the magnetic properties of such potential diluted magnetic semiconductors. However, only Fe_0.2Zn_0.8O was ferromagnetic at room temperature. The Co-doped sample showed Curie鈭扺eiss behavior up to a doping level of 30 atom %. According to X-ray absorption fine structure (XAFS) measurements, at high doping levels the Fe-doped ZnO samples contain an increasing fraction of Fe³⁺ ions (in addition to Fe²⁺), whereas Co is predominantly in the oxidation state of +2. Clustering of Fe ions into amorphous ferromagnetic Fe₃O₄ within the ZnO host and the magnetic interactions between the Fe₃O₄ regions is a possible explanation for the ferromagnetic properties.