Browsing by Author "Chiang, CY"

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    Domination of second-sphere shrinkage effect to improve photoluminescence of red nitride phosphors
    (ACS Publications, 2014-11-14) Huang, WY; Yoshimura, F; Ueda, K; Pang, WK; Su, BJ; Jang, LJ; Chiang, CY; Zhou, WZ; Duy, NH; Liu, RS
    Red Ca0.99Al1–4δ/3–xSi1+δ+xN3–xCx:Eu2+0.01 (δ = 0.345; x = 0–0.2) nitride phosphors exhibit a blue-shifted emission with increased eye sensitivity function and excellent thermal stability. The variations in the photoluminescence in the Ca0.99Al1–4δ/3–xSi1+δ+xN3–xCx:Eu2+0.01 (δ = 0.345; x = 0–0.2) system are thoroughly investigated. The enhanced emission energy and the improved thermal stability with increasing x are dominated by the second-sphere shrinkage effect via the substitution of small Si4+ for large Al3+ with simultaneous charge compensation. Related proofs of the second-sphere shrinkage effect control for photoluminescence are confirmed via high-resolution neutron powder diffraction, EXAFS, and 29Si solid-state NMR techniques. © 2014, American Chemical Society.
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    Real-time investigation of the structural evolution of electrodes in a commercial lithium-ion battery containing a V-added LiFePO4 cathode using in-situ neutron powder diffraction
    (Elsevier Science BV, 2013-12-15) Hu, CW; Sharma, N; Chiang, CY; Su, HC; Peterson, VK; Hsieh, HW; Lin, YF; Chou, WC; Shew, BY; Lee, CH
    In-situ neutron powder diffraction was employed to investigate the structural evolution of the electrode materials in a commercial lithium-ion battery used for electric buses in Taiwan. The battery, containing a vanadium-added LiFePO4 cathode, does not exhibit a delayed phase transition between LiFePO4 (triphylite) and FePO4 (heterosite) suggesting that the delayed phase transition can be suppressed through the use of vanadium-added LiFePO4 cathodes, which also enhances the capacity and prolongs the cycle life of these batteries. Furthermore, we characterize the readily reversible structural change of the anode (LixC6 where 0 < x <= 1) and correlate this to battery voltage. © 2013, Elsevier Ltd.
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    Vanadium substitution of LiFePO4 cathode materials to enhance the capacity of LiFePO4-based lithium-Ion batteries
    (American Chemical Society, 2012-11-22) Chiang, CY; Su, HC; Wu, PJ; Liu, HJ; Hu, CW; Sharma, N; Peterson, VK; Hsieh, HW; Lin, YF; Chou, WC; Lee, CH; Lee, JF; Shew, BY
    The mechanism of enhancing the capacity of the LiFePO(4) cathodes in lithium ion batteries by the addition of a small amount of vanadium, which locate on the lithium site and induce lithium vacancies in the crystal structure, is reported in this article. As a result, the capacity increases from 138 mAh/g found for pristine LiFePO(4) to 155 mAh/g for the V-added compound, and the conductivity increases from 4.75 x 10(-4) S/cm for the LiFePO(4) without V addition to 1.9 x 10(-2) S/cm for the V-added compound. A possible model to facilitate the enhancement of conductivity and capacity is described with evidence supported by X-ray powder diffraction, X-ray absorption spectroscopy, and neutron powder diffraction data. © 2012, American Chemical Society.