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Sun R.,Southwest University of Science and Technology | Yan W.,Southwest University of Science and Technology | Liu J.,Southwest University of Science and Technology | Liu J.,Oeans King Lighting Science and Technology Co. | And 2 more authors.
Kuei Suan Jen Hsueh Pao/Journal of the Chinese Ceramic Society | Year: 2010

Eu3+-doped CaCO3 red phosphors with a final mole ratio of Ca2+ to Eu3+ at 100:1 were synthesized via a low temperature hydrothermal route at 150°C for different reaction time. The morphology, structure and luminescent properties of the samples were characterized by scanning electron microscopy, X-ray powder diffraction, photoluminescence and photoluminescence excitation (PL-PLE) spectra, respectively. The results indicate that the samples of the calcite have cubic shape and the aragonite with needle-like shape. The mole ratio of aragonite to calcite increases with increasing of the reaction time. When reaction time to reach 24 h, the luminescent intensity of CaCO3:Eu3+ is the highest, and the sample has evenly dispersed the aragonite with needle-like shape. Eu3+ acts as a luminescent center to replace the Ca2+ site in the different crystal lattices and locate in an asymmetric position. The PLE spectra of all samples show that the main intense broad band with the maximum at about 277 nm is contributed by the charge transfer transition of Eu3+-O2-, and the week sharp lines in 300-550 nm range in the spectra are assigned to the intra-configurational 4f-4f transitions of Eu3+. The maximal emission peak locates in the vicinity of 614 nm, corresponding to electric-dipole transition 5D0→7F2 of Eu3+. Source


Kang M.,Southwest University of Science and Technology | Yan W.-Q.,Southwest University of Science and Technology | Liu J.,Southwest University of Science and Technology | Liu J.,Oeans King Lighting Science and Technology Co. | And 4 more authors.
Sichuan Daxue Xuebao (Gongcheng Kexue Ban)/Journal of Sichuan University (Engineering Science Edition) | Year: 2011

The Tb3+-doped strontium carbonate phosphor was synthesized via co-precipitation route by microwave assisted. The phosphor powders were characterized by scanning electron microscopy(SEM), X-ray diffraction(XRD) and photoluminescence and photoluminescence excitation(PL-PLE) spectrum. The results showed that Tb3+ acting as a luminescent center probed into the single orthorhombic phase of SrCO3 with flake-like and sphericity-like. The PLE spectrum showed a broadband absorption center in 231 nm, which belonged to 4f7→5d1 transition. The sample was the green phosphor since the maximum emission peak located in the vicinity of 543 nm, corresponding to the transition of 5D4→7F5. The luminescent intensities increased with increasing Tb3+ concentration, and then decreased because of concentration quenching. The optimal concentration of Tb3+ was 3.5 mol%. The concentration self-quenching mechanism is exchange interaction. Source


Yan W.-Q.,Southwest University of Science and Technology | Kang M.,Southwest University of Science and Technology | Liu J.,Southwest University of Science and Technology | Liu J.,Oeans King Lighting Science and Technology Co. | And 2 more authors.
Rengong Jingti Xuebao/Journal of Synthetic Crystals | Year: 2010

Eu3+-doped strontium carbonate phosphor was synthesized by microwave assisted co-precipitation method. The structure, morphology and spectrum properties were characterized by X-ray diffraction(XRD), scanning electron microscopy (SEM) and photoluminescence and photoluminescence excitation(PL-PLE) spectrum, respectively. The effect of excitation wavelength and Eu3+ concentration on the luminescence properties were studied. The results reveal that Eu3+ acted as a luminescent center probe into the single orthorhombic phase SrCO3 located in an asymmetric position. The PLE spectrum shows a broadband absorption center in 284 nm, which belongs to Eu3+-O2- charge transfer transition, and several series of narrow peaks at 393 nm and 464 nm, and so on, which belonged to f-f transition. The sample is the pure red phosphor since the maximum emission peak locate in the vicinity of 614 nm, corresponding to the transition of 5D0→7F2. The luminescent intensities increase as Eu3+ concentration increasing, and then decrease because of concentration quenching. The optimal concentration of Eu3+ was 3 mol% excitate at 284 nm, while 12 mol% excitate at 393 nm or 464 nm. The concentration self-quenching mechanism is the dipole-dipole interaction according to the Dexter theory. In addition, the SrCO3:Eu3+ red phosphor powders would have the great potential application for fluorescent lamp and LED fields. Source

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