Sonochemical processing of ZnO-Ce doped structures prepared by different precursors

Full text: Zinc oxide is a semiconducting material with a large potential for a variety applications. Many of its properties, such as, high electron mobility and thermal conductivity, wide and direct band gap, about 3,3 eV, makes ZnO suitable for applications in a variety of devices, like gas and chemical sensors, solar cells, among many others [1]. Furthermore, rare-earth doping in ZnO may result in modifications of their properties that can improve performance for some applications [2]. In this work, initially, two samples (pure ZnO, and 1 at % Ce-doped ZnO) were prepared from sonochemical method using the commercial powders of ZnO and CeO₂ as precursors reagents. Similarly, two samples (pure ZnO and 1 at% Ce-doped ZnO) were prepared from zinc and cerium nitrates. All the samples were characterized by X ray diffraction (XRD) associated to Rietveld structural refinement, scanning electron microscopy (SEM) and Uv-Vis spectroscopy. For sample with Ce addition synthetized from oxides as precursors, a second phase of CeO₂ was detected, suggesting dopant atoms segregation. Rietveld structural refinements for this sample evidenced low dopant incorporation. The same was not observed for the ZnO-Ce sample prepared from nitrates, wherein X-ray diffraction studies and Rietveld refinements indicate single phase sample. However SEM analyzes for this sample evidenced the CeO₂ segregation. It was also detected the occurrence of fragmentation and sintering between the particles for samples prepared from oxides, phenomena predicted by literature about the synthesis method. Samples synthetized from nitrates showed a different morphology, wherein a distribution of flower-like structures were observed. No changes were observed in band gap values for samples with Ce addition. References: [1] Janotti, A., Van de Walle, C. G.; Rep. Prog. Phys., 72, 2009. [2] Panda, N. R., et al.; J. Luminescence, 136, 369-377, 2013. (author)