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摘要
Single-phases of the spinet nanoferrites Zn0.5Co0.5Al0.5R0.04Fe1.46O4; R=Sm, Pr, Ce and 12, were synthesized using the flash auto combustion method. X-ray diffraction (XRD) results indicated that doping nanoferrites with small concentrations of rare earth elements (RE) allowed their entrance to the spinet lattice. Transmission electron microscope (TEM) images revealed that doping with different RE elements resulted in the formation of different nanometric shapes such as nanospheres and nanowires. Doping with Sm3+ and Ce3+ resulted in the formation of nanospheres with average diameter of 14 and 30 nm respectively. In addition to the granular nanospheres, doping with Pr3+ and La3+ resulted in the formation of some nanowires with different aspect ratios (average length of approximate to 100 nm and diameter of approximate to 9 nm) and (average length of approximate to 150 nm and outer diameter of approximate to 22 nm) respectively. At fixed temperature, the Ac conductivity (sigma) increased as the RE ionic radius increases except for Ce, due to the role of valance fluctuation from Ce3+ to Ce4+ ions. La- and Pr-doped nanoferrites showed the highest ac conductivity values, which is most probably due to the presence of large numbers of nanowires in these two types of ferrites. For all entire samples, the effective magnetic moment (mu(eff)) decreased, while the Curie temperature (T-C) increased as the RE ionic radius increases. The synthesized rare earth nanoferrites showed promising results in purifying colored wastewater. La-doped ferrite was capable for up taking 92% of the dye content, followed by Pr-doped ferrite, which adsorbed 85% of the dye, while Sm- and Ce-doped ferrites showed lower dye removal efficiency of 80% and 72% respectively. High dye uptake shown by La- and Pr-doped ferrites is most probably due to the presence of nanowires and their higher Ac conductivity values. These excellent results were not previously reported.
- 出版日期2014-1
