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Chen S.-D.,Kunming University of Science and Technology | Chen S.-D.,Key Laboratory of Advanced Materials of Yunnan Province | Chen J.-C.,Kunming University of Science and Technology | Chen J.-C.,Key Laboratory of Advanced Materials of Yunnan Province
Transactions of Nonferrous Metals Society of China (English Edition) | Year: 2012

Based on the research on the solidification of twin-roll continuous casting aluminum thin strip, the analytical model of heterogeneous nucleation, the growth kinetics of tip (KGT) and columnar dendrite transformation to equiaxed dendrite (CET) of twin-roll continuous casting aluminum thin strip solidification was established by means of the principle of metal solidification and modern computer emulational technology. Meantime, based on the cellular automaton, the emulational model of twin-roll continuous casting aluminum thin strip solidification was established. The foundation for the emulational simulation of twin-roll casting thin strip solidification structure was laid. Meanwhile, the mathematical simulation feasibility was confirmed by using the solidification process of twin-roll continuous casting aluminum thin strip. © 2012 The Nonferrous Metals Society of China. Source


Gao Y.,Kunming University of Science and Technology | Hu Y.,Kunming University of Science and Technology | Ren P.,Kunming University of Science and Technology | Zhou D.,Kunming University of Science and Technology | And 3 more authors.
Journal of the European Ceramic Society | Year: 2016

Cubic-to-hexagonal phase transformation and enhancement of upconversion emission are simultaneously achieved by modifying the ratio of ZnO/Na2O content in the Tb3+-Yb3+ co-doped oxyflouride Zincatesilion glass ceramics containing NaYF4 nanocrystals. XRD and TEM data have revealed that the crystallization of NaYF4 from α phase to β phase. Additionally, upconversion emissions were obtained from these Tb3+-Yb3+ glass ceramics under 980 nm excitation. Compared with the cubic α-NaYF4 nanocrystals of glass ceramics, the upconversion intensity augmented drastically owing to the phase transformation that the NaYF4 has changed from α into β. Therefore, the PL results showed that the cubic-to-hexagonal the NaYF4:Eu3+ lattice could induce a remarkable change of the PL intensity in red region (R = IED/IMD) with 393 nm excitation wavelength. It was indicated that it changed the phase transformation in Tb-Yb on symmetry of the lattice. © 2016 Elsevier Ltd. Source


Gao Y.,Kunming University of Science and Technology | Hu Y.,Kunming University of Science and Technology | Ren P.,Kunming University of Science and Technology | Zhou D.,Kunming University of Science and Technology | And 3 more authors.
Journal of Alloys and Compounds | Year: 2016

The glass ceramics samples with composition of 40SiO2-25Al2O3-18Na2CO3-10YF3-7NaF-0.5TbF3-1YbF3-xLi2CO3 (in mol%, x = 0, 1, 2, 3, 4, 5 and 6) were prepared using the conventional quenching techniques. The effect of the Li+ codoping on the enhancement upconversion (UC) and Stokes emission in Tb-Yb co-doped transparent glass-ceramics were investigated. Compared with the glass-ceramics sample without Li+ codoping, the UC and Stokes emission intensity of glass-ceramics samples with Li+ codoping were increased. Particularly, the green UC emission intensity band centered at 543 nm was strongly increased twice with the increase of Li+ up tp 4 mol%. Therefore, the Stokes emission results showed that the incorporation of Li+ ions into the NaYF4:Eu3+ lattice could induce a remarkable change of the Stokes emission intensity in red region (R = IED/IMD) with 393 nm excitation wavelength. It was indicated that it improved the effect of Li+ codoping in Tb-Yb on symmetry of the lattice. The possible mechanism responsible for the enhancement of UC and Stokes emission in Tb3+-Yb3+ co-doped were discussed. © 2016 Elsevier B.V. All rights reserved. Source


Zhou H.,Kunming University of Science and Technology | Yu X.,Kunming University of Science and Technology | Yu X.,Key Laboratory of Advanced Materials of Yunnan Province | Qian S.,Kunming University of Science and Technology | And 8 more authors.
Materials Research Bulletin | Year: 2013

Eu3+ and Bi3+ co-activated Ca3SnSi 2O9 phosphors were synthesized by the solid-state reaction. The blue and red emission were observed in Ca3SnSi 2O9 host and Eu3+ doped samples, of which ascribed to the self-activated emission of host matrix and the characteristic emissions of Eu3+, respectively. Furthermore, by codoped with Bi 3+, the emission intensity of Eu3+ located at 612 nm was significant enhanced, owing to the energy transfer from Bi3+ to Eu3+, which is beneficial to the color tunability of Ca 3SnSi2O9: Eu3+, Bi3+ phosphor. © 2013 Elsevier Ltd. Source


Wang P.,Kunming University of Science and Technology | Xu X.,Kunming University of Science and Technology | Xu X.,Key Laboratory of Advanced Materials of Yunnan Province | Qiu J.,Kunming University of Science and Technology | And 4 more authors.
Optical Materials | Year: 2014

A greenish-blue long-persistent luminescence (LPL) material of Ba 4(Si3O8)2:Eu2+,Er 3+ was synthesized by traditional solid state reaction method. Compared to Eu2+ single-doped Ba4(Si3O 8)2 phosphor, the Eu2+/Er3+ co-doped sample shows brighter and longer afterglow. Photoluminescence (PL) and long-persistent luminescence (LPL) results indicated that PL and LPL are from the same luminescent centers which are ascribed to the 4f65d 1 → 4f7 transition of the Eu2+. The incorporation of Er3+ ions largely extends the thermoluminescence characteristics and evidently enhances the LPL behavior of the phosphor. Since the TL glow curve in the Eu2+/Er3+ co-doped sample phosphor is different from that of Er3+ single-doped sample, it is considered that Er3+ plays an important role in LPL behavior. © 2014 Elsevier B.V. All rights reserved. Source

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