tailieunhanh - Báo cáo hóa học: " Effects of crystallization and dopant concentration on the emission behavior of TiO2: Eu nanophosphors"

Tuyển tập các báo cáo nghiên cứu về hóa học được đăng trên tạp chí hóa hoc quốc tế đề tài : Effects of crystallization and dopant concentration on the emission behavior of TiO2: Eu nanophosphors | Pal et al. Nanoscale Research Letters 2012 7 1 http content 7 1 1 o Nanoscale Research Letters a SpringerOpen Journal NANO COMMENTARY Open Access Effects of crystallization and dopant concentration on the emission behavior of TiO2 Eu nanophosphors Mou Pal Umapada Pal Justo Miguel Gracia Y Jimenez and Felipe Pérez-Rodríguez Abstract Uniform spherical-shaped TiO2 Eu nanoparticles with different doping concentrations have been synthesized through controlled hydrolysis of titanium tetrabutoxide under appropriate pH and temperature in the presence of EuCl3-6H2O. Through air annealing at 500 C for 2 h the amorphous as-grown nanoparticles could be converted to a pure anatase phase. The morphology structural and optical properties of the annealed nanostructures were studied using X-ray diffraction scanning electron microscopy energy-dispersive X-ray spectroscopy EDS and UV-Visible diffuse reflectance spectroscopy techniques. Optoelectronic behaviors of the nanostructures were studied using micro-Raman and photoluminescence PL spectroscopies at room temperature. EDS results confirmed a systematic increase of Eu content in the as-prepared samples with the increase of nominal europium content in the reaction solution. With the increasing dopant concentration crystallinity and crystallite size of the titania particles decreased gradually. Incorporation of europium in the titania particles induced a structural deformation and a blueshift of their absorption edge. While the room-temperature PL emission of the as-grown samples is dominated by the 5D0 - 7Fj transition of Eu 3 ions the emission intensity reduced drastically after thermal annealing due to outwards segregation of dopant ions. Keywords titania nanoparticles europium doping optical properties photoluminescence Introduction Luminescent nanomaterials have gained considerable attention in recent years due to the breakthrough developments of technology in various areas such as electronics 1 2 .

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