Magnetic behavior of nanocrystalline powders of Co-doped ZnO diluted magnetic semiconductors synthesized by polymerizable precursor method
Magnetic behavior of nanocrystalline powders of Co-doped ZnO diluted magnetic semiconductors synthesized by polymerizable precursor method
复制标题
DOI：
10.1016/j.jmmm.2005.07.020
复制
发表时间：
2006-06
影响因子：
2.7
通讯作者：
S. Maensiri;Jakkapon Sreesongmuang;C. Thomas;Jutharatana Klinkaewnarong
中科院分区：
文献类型：
--
作者：
S. Maensiri;Jakkapon Sreesongmuang;C. Thomas;Jutharatana Klinkaewnarong
本文首次报道了以锌钴硝酸盐为络合剂，以柠檬酸和乙二醇的混合溶液为反应介质，采用可聚合前驱体法制备掺钴氧化锌(即锌钴0.1O)稀磁半导体纳米晶粉末的方法。用热重-差热分析(TG-DTA)对前驱体进行了表征，确定了其热分解结晶温度为723K。前驱体在773、873、973和1073K的不同温度下焙烧1h，得到纳米晶粉末。用扫描电子显微镜、透射电子显微镜和谢雷尔方程对焙烧后颗粒的形貌和晶粒度进行了表征。经773、873、973和1073K焙烧1h后的平均粒径分别为20、60、80、150 nm。X-射线衍射仪和傅立叶红外光谱分析表明，合成的Zn0.9Co0.1O具有纯的纤锌矿结构，Co掺杂对其结构没有明显的影响。光学吸收测量表明，Co2+取代了Zn2+的存在。室温磁化结果表明，Zn0.9Co0.1O粉末具有铁磁性。虽然比磁化强度似乎随着颗粒大小的变化而变化，但没有明显的相关性，因为在873K(60 Nm)下焙烧的粉末磁化强度最大。相反，比磁化强度似乎表现出依赖于纤锌矿晶胞的晶格常数c的趋势。
This paper reports the first synthesis of nanocrystalline powders of Co-doped ZnO (i.e. Zn0.9Co0.1O) diluted magnetic semiconductor by a polymerizable precursor method using nitrate salts of Zn and Co and a mixed solution of citric acid and ethylene glycol as a chelating agent and reaction medium, respectively. The polymeric precursors were characterized by TG-DTA to determine the thermal decomposition and crystallization temperature which was found to be at 723K. The precursors were calcined at different temperatures of 773, 873, 973, and 1073K for 1h to obtain nanocrystalline powders. The morphology and crystalline size of the calcined particles were evaluated by SEM, TEM and Scherrer's equation. The average particle sizes calcined at 773, 873, 973, and 1073K for 1h were, respectively, 20, 60, 80, 150nm, obtained from TEM. The XRD and Fourier transmission infrared (FT-IR) results indicated that the synthesized Zn0.9Co0.1O powders have the pure wurtzite structure without any significant change in the structure affected by Co substitution. Optical absorption measurements showed absorption bands indicating the presence of Co2+in substitution of Zn2+. Room temperature magnetization results revealed a ferromagnetic behavior for the Zn0.9Co0.1O powders. Although the specific magnetization seemed to change with the particle size but there was no clear dependency since the largest magnetization was observed in the powders calcined at 873K (60nm). Instead, the specific magnetization appeared to show a trend of dependency on the lattice constant c of the wurtzite unit cell.