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A novel yellow emitting phosphor Dy3+, Bi3+ co-doped YVO4 potentially for white light emitting diodes 下载免费PDF全文
Novel Y1 x yVO4:xDy3+,yBi3+(0.01 ≤ x ≤ 0.05,0 ≤ y ≤ 0.20) phosphors for light emitting diode(LED) were successfully synthesised by solid-state reaction.The calculation results of electronic structure show that YVO4 has a direct band gap with 3 eV at G.The top of the valence band is dominated by O 2p state and the bottom of the conduction band is mainly composed of O 2p and V 3d states.An efficient yellow emission under near-ultraviolet(365 nm) excitation is observed.Compared with the pure YVO4:Dy3+ samples,the Dy3+,Bi3+ co-doped samples show a more intensive emission peak(at 574 nm) and a new broad emission band(450-770 nm),due to the 4F9/2 6H13/2 transition of Dy3+ and the emission of the VO3 4 Bi3+ complex respectively.The optimum chromaticity index of Y1 x yVO4:xDy3+,yBi3+(0.01 ≤ x ≤ 0.05,0 ≤ y ≤ 0.20) is(0.447,0.497),which indicates that YVO4:Dy3+,Bi3+ has higher colour saturation than the commercial phosphor YAG:Ce3+.The effects of concentration of Dy3+,Bi3+,electric states and the photoluminescence properties are discussed in details. 相似文献
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Hydrothermal Synthesis and Vacuum Ultraviolet-Excited Luminescence Properties of Novel Dy^3+-doped GdPO4 White Light Phosphors 下载免费PDF全文
Novel Dy^3+-doped GdPO4 white light phosphors with a monoclinic system are successfully synthesized by the hydrothermal method at 240℃. The strong absorption at around 147nm in the excitation spectrum is assigned to the host absorption. It is suggested that the vacuum ultraviolet excited energy is transferred from the host to the Dy^3+ ions. The f - d transition of the Dy^3+ ion is observed to be located at 182nm, which is consistent with the calculated value using Dorenbos's expression. Under 147nm excitation, Gd0.92PO4:0.08Dy^3+ phosphor exhibits two emission bands located at 572 nm (yellow) and 478 nm (blue), which correspond to the hypersensitive transitions ^4 F9/2-^6 H13/2 and ^4 F9/2-^6 H15/2. The two emission bands lead to the white light. Because of the strong absorption at about 147nm, Gd0.92PO4:0.08Dy^3+ under vacuum ultraviolet excitation is an effective white light phosphor, and has promising applications to mercury-free lamps. 相似文献
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伴随着数值天气预报和气候变化研究精细化程度的不断提高, 希望探空温度传感器的观测精度达到0.1 K数量级. 为了实现此目标, 运用计算流体动力学方法对珠状热敏电阻从海平面上升至20 km高空的整个过程进行数值仿真分析. 并在此基础上, 针对影响测温精度的太阳辐射强度和传感器倾斜角度两个因素进行分析. 仿真结果表明, 太阳辐射强度和海拔高度是辐射误差的重要影响因子. 当传感器倾斜角度为90°时, 珠状热敏电阻的辐射误差最小. 通过麦夸特法和通用全局优化法对仿真数据进行拟合, 获得不同海拔高度和太阳辐射强度下的辐射误差修正方程; 为验证方程的准确性, 设计和搭建太阳辐射误差模拟系统. 实验结果表明, 辐射误差实验测量值与修正方程修正值之间的平均偏移量为0.017 K, 均方根值RMS误差为0.023 K, 验证了计算流体动力学方法、麦夸特法和通用全局优化法获得辐射误差数据的准确性. 相似文献
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Shang-Yi Shen Jia-Chi Chen Shang-Hao Liu Ron-Hsin Chang Horng-Jang Liaw Chi-Min Shu 《Journal of Thermal Analysis and Calorimetry》2013,113(3):1619-1624
Determining the explosion limits of chemical substances is exceptionally critical while considering prevention of loss in manufacturing processes. The accidental explosions of flammable liquid/gas mixtures are second to none in loss prevention issues. In a previous study, we found a theoretical linear correlation between the reciprocal of the explosion limits and the reciprocal of the molar fraction of hydrocarbons diluted with inert carbon dioxide or nitrogen. In this study, we estimated the effects of inert liquid/gas (H2O), which dilute flammable vapors or gases. The experiments measured the explosion limits of isopropyl alcohol with steam at initial conditions of 1 atm and 150 °C by a 20-L-apparatus. We compared the experimental values with the theoretical model, and found that a linear correlation still exists. The results demonstrated that the experimental values fit the theoretical model well. 相似文献
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采用高温固相法合成了发光材料Ca2GeO4 ∶Eu3+ ,并详细研究了其紫外-真空紫外发光特性. 发现并解释了Eu3+ 离子在空气中的自还原以及在不同波长激发下的颜色转换现象. Ca2GeO4 ∶Eu3+ 在163—230和301,466 nm处具有强激发带,表明Ca2GeO4 ∶Eu3+
关键词:
2GeO4 ∶Eu3+')" href="#">Ca2GeO4 ∶Eu3+
光致发光机理
空气中自还原
颜色转换 相似文献
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Photoluminescence and persistent luminescence properties of non-doped and Ti4+-doped Mg2SnO4 phosphors 下载免费PDF全文
Mg2SnO4 exhibits green photoluminescence and persistent luminescence, which originate from oxygen vacancies. When Ti4+ ions were doped, an interesting Mg2SnO4:Ti4+ phosphor with bluish white photoluminescence under ultraviolet irradiation and with green persistent luminescence was first obtained. Our investigation reveals that two emission centres exist in Mg2SnO4:Ti4+. The centres responsible for the green emission are considered to be the F centres (oxygen vacancies) and the blue centres are the TiO6 complex. Trap clusters in the band gap with different depths, such as [SnMg‥—Oi″], [SnMg‥—VO·], [SnMg‥—VO×] and MgSn″, correspond to the components at 85 ℃, 146 ℃ and 213 ℃ of the thermoluminescence curve. 相似文献