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10 results on '"Deng, Ke-Jian"'

5. Preparation of Ca 4 Mg 5 (PO 4 ) 6 :Eu 2+ , Mn 2+ phosphor and its photoluminescence properties

Author

Deng Ke-jian, Fu Tingting, Tang Wanjun, and Wu Ming

Subjects
Photoluminescence, Materials science, Process Chemistry and Technology, Doping, Analytical chemistry, Phosphor, Photon upconversion, Surfaces, Coatings and Films, Electronic, Optical and Magnetic Materials, X-ray crystallography, Materials Chemistry, Ceramics and Composites, Emission spectrum, Luminescence, Excitation
Abstract

Eu2+ and Mn2+ singly doped and Eu2+/Mn2+-codoped Ca4Mg5(PO4)6 phosphors were synthesized via combustion synthesis. Mn2+-singly doped Ca4Mg5(PO4)6 phosphor exhibits a single red emission in the wavelength range of 500–700 nm due to the 4T1(4G)→6A1(6S) transition of Mn2+. Eu2+/Mn2+ co-doped phosphor emits two distinctive luminescence bands: a blue one centered at 442 nm originating from Eu2+ and a broad red-emitting one peaked at 609 nm from Mn2+. Energy transfers from Eu2+ to Mn2+ were discovered by directly observing significant overlap of the excitation spectrum of Mn2+ and the emission spectrum of Eu2+ as well as the systematic relative decline and growth of emission bands of Eu2+ and Mn2+, respectively. Based on the principle of energy transfer, the relative intensities of blue and red emission could be tuned by adjusting the contents of Eu2+ and Mn2+.

Published
2013

10. Effects of titanium incorporation on phase and electrochemical performance in LiFePO4 cathode material

Author

Wang, Zhao-Hui, Pang, Quan-Quan, Deng, Ke-Jian, Yuan, Li-Xia, Huang, Fei, Peng, Yun-Long, and Huang, Yun-Hui

Subjects
*LITHIUM-ion batteries, *TITANIUM, *X-ray diffraction, *ELECTRIC discharges, *CYCLIC voltammetry, *SOLID state chemistry, *SURFACE coatings, *ELECTRIC conductivity
Abstract

Abstract: Ti-incorporated LiFe1−x Ti x PO4 (0≤ x ≤0.2) samples have been prepared via a two-step solid-state reaction route. The samples have systematically been investigated with X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, scanning electron microscope (SEM), transmission electron microscope (TEM), cyclic voltammetry (CV) and charge/discharge measurements. The incorporation of Ti in LiFePO4 significantly enhances the electrochemical performance; the carbon-coated LiFe0.9Ti0.1PO4 sample shows the best performance. It is confirmed that LiFe1−x Ti x PO4 with x ≤0.05 are of single phase while those with 0.07≤ x ≤0.2 contain impurity phases: LiTi2(PO4)3 and TiP2O7. The impurities influence not only the electronic conductivity, but also the total specific capacity. Appropriate amount of titanium incorporation is favorable for the improvement in electrochemical performance. [Copyright &y& Elsevier]

Published
2012
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