Sapra Sameer, Nanda J, Anand A, Bhat S V, Sarma D D
Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore 560012, India.
J Nanosci Nanotechnol. 2003 Oct;3(5):392-400. doi: 10.1166/jnn.2003.211.
We report the synthesis of fixed-size ZnS nanoclusters approximately 24 A in diameter with varying manganese concentrations. Various samples of Zn1-x MnxS, with x = 0, 0.02, 0.055, 0.09, and 0.13, have been prepared and characterized using X-ray diffraction, energy-dispersive analysis of X-rays, UV absorption, fluorescence emission and excitation, electron paramagnetic resonance (EPR), and magnetic susceptibility measurements. The manganese ions are found to substitute Zn randomly without giving rise to any clustering of Mn sites, as seen from EPR and magnetic susceptibility results. Our studies reveal that the band gap of the doped nanoclusters passes through a maximum as the manganese concentration is varied. Also, we observe orange emission from Mn2+ ions in the doped ZnS nanoclusters, apart from the blue emission characteristic of the ZnS defect states. The relative intensity of the orange emission compared with the blue varies with the manganese concentration in a nonmonotonic way. The inverse of susceptibility temperature plots can be plotted onto a universal curve by simple multiplicative constants, thus showing that the magnetic interactions between Mn2+ ions are weak.
我们报道了直径约为24埃、锰浓度不同的固定尺寸硫化锌纳米团簇的合成。制备了x = 0、0.02、0.055、0.09和0.13的各种Zn1-x MnxS样品，并使用X射线衍射、X射线能量色散分析、紫外吸收、荧光发射与激发、电子顺磁共振（EPR）以及磁化率测量对其进行了表征。从EPR和磁化率结果可以看出，锰离子随机取代锌，不会导致锰位点出现任何聚集。我们的研究表明，随着锰浓度的变化，掺杂纳米团簇的带隙会出现一个最大值。此外，除了硫化锌缺陷态的蓝色发射特征外，我们还观察到掺杂的硫化锌纳米团簇中锰离子发出的橙色发射。与蓝色发射相比，橙色发射的相对强度随锰浓度呈非单调变化。通过简单的乘法常数，可以将磁化率温度曲线的倒数绘制到一条通用曲线上，这表明锰离子之间的磁相互作用较弱。
