Microstructural and photoluminescence properties of sol-gel derived Tb³⁺ doped ZnO nanocrystals

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• 作者：Guy L. Kabongo ; Gugu H. Mhlongo ; Thomas Malwela ; Bakang M. Mothudi ; Kenneth T. Hillie ; Mokhotjwa S. Dhlamini
• 关键词：Sol&ndash ; gel ; Zinc oxide ; Terbium ; Quantum dots ; Band gap ; Photoluminescence
• 刊名：Journal of Alloys and Compounds
• 出版年：5 April, 2014
• 年：2014
• 卷：591
• 期：Complete
• 页码：156-163
• 全文大小：3037 K

文摘

Un-doped and Tb³⁺ doped ZnO nanocrystals with different concentrations of Tb³⁺ were synthesized by a sol-gel method and their photoluminescence (PL) properties were investigated. The successful incorporation of Tb³⁺ ions with different concentration (0.15, 0.5 and 1 mol %) in ZnO was realized and confirmed through different characterization. High crystalline ZnO products were produced without the need of a post-heat treatment. Elemental mapping conducted on the as prepared samples using Scanning electron microscope (SEM) equipped with energy dispersive X-ray spectrometer (EDX) revealed homogeneous distribution of Zn, O, and Tb ions. The high resolution transmission electron microscope (HR-TEM) analyses indicated that the un-doped and Tb³⁺ doped samples were composed of homogeneously dispersed particles of high crystallinity with an average size ranging from 3 to 6 nm in diameter, which was in agreement with X-ray diffraction (XRD) analyses. Raman spectroscopy was used to further elucidate the wurtzitic structure of the prepared samples. PL study revealed that among different Tb³⁺ concentrations, 0.5 mol% Tb³⁺ doped ZnO nanoparticles showed clear emission from the dopant originating from the 4f-4f intra-ionic transitions of Tb³⁺ while the broad defects emission was dominating in the 0.15 and 1 mol% Tb³⁺ doped ZnO. Optical band gap was extrapolated from the Ultraviolet Visible spectroscopy (UV-Vis) absorption analysis using TAUC鈥檚 method and the widening of the optical band gap for the 0.15 and 0.5 mol% Tb³⁺ doped samples and the reduction of the optical band gap for the 1 mol% Tb³⁺ doped sample as compared to the un-doped sample was observed. Energy transfer mechanism between Tb³⁺ and ZnO is discussed in detail.