Eu2＋ and Dy3＋ codoped （Ca, Sr）7（SiO3）6C12 yellow phosphors were successfully synthesized by self-flux method. The structure, morphology and photoluminescence properties were investigated by X-ray diffraction （...Eu2＋ and Dy3＋ codoped （Ca, Sr）7（SiO3）6C12 yellow phosphors were successfully synthesized by self-flux method. The structure, morphology and photoluminescence properties were investigated by X-ray diffraction （XRD）, scanning electron microscopy （SEM） and photoluminescence spectra. The as-prepared phosphor showed a broad emission spectrum centered at 550 nm for Eu2＋ single-doped phosphor, while located at 548 544 nm for the Eu2＋, Dy3＋ codoped samples under excitation at 380 nm light. The emission intensity was greatly improved when Dy3＋ was doped into the （Ca,Sr）7（SiO3）6C12：Eu2＋ system. The composition-optimized sample with 3 mol.% of Dy3＋ and constant 10 tool.% of Eu2＋ exhibited a 220% PL enhancement compared to the phosphor with 10 tool.% Eu2＋ single-doped. Meanwhile, it was found that the quantum efficiency of phosphor namely （Ca,Sr）7（SiO3）6Cl2：3 tool.% Dy3＋ 10 mol.% Euz＋ could get up to 24.6%. The synthesized yellow-emitting （Ca,Sr）7（SiO3）6C12：Dy3＋,Eu2＋ is a promising candidate as high-efficiency yellow phosphor for NUV-excited white LEDs.展开更多
A series of big single crystals of BaFeFe2-xNixAs2 have been prepared by the FeAs self-flux method, with nominal nickel doping x = 0--0.12. The dimensions of the cleaved crystals are over 10~mm along ab plane and ～ 2...A series of big single crystals of BaFeFe2-xNixAs2 have been prepared by the FeAs self-flux method, with nominal nickel doping x = 0--0.12. The dimensions of the cleaved crystals are over 10~mm along ab plane and ～ 2~mm in maximum along the c direction. The measurements of x-ray diffraction, electrical resistance and magnetic property are carried out on the crystals. For the undoped parent compound BaFe2As2, both resistance and magnetization data display an anomaly associated with spin density wave and/or structural phase transition, with the transition temperatures at ～ 138~K. For Ni-doped BaFe2-xNixAs2 crystals, the superconducting critical temperature Tc ranges from 4.3~K for x=0.06 sample to 20~K for the optimally doped x=0.10 crystal.展开更多
基金Project supported by Shanghai Education Committee Research Project(08YZ166,11YZ222)Shanghai Science and Technology Committee Project(09530500800)National Natural Science Foundation of China(51002096)
文摘Eu2＋ and Dy3＋ codoped （Ca, Sr）7（SiO3）6C12 yellow phosphors were successfully synthesized by self-flux method. The structure, morphology and photoluminescence properties were investigated by X-ray diffraction （XRD）, scanning electron microscopy （SEM） and photoluminescence spectra. The as-prepared phosphor showed a broad emission spectrum centered at 550 nm for Eu2＋ single-doped phosphor, while located at 548 544 nm for the Eu2＋, Dy3＋ codoped samples under excitation at 380 nm light. The emission intensity was greatly improved when Dy3＋ was doped into the （Ca,Sr）7（SiO3）6C12：Eu2＋ system. The composition-optimized sample with 3 mol.% of Dy3＋ and constant 10 tool.% of Eu2＋ exhibited a 220% PL enhancement compared to the phosphor with 10 tool.% Eu2＋ single-doped. Meanwhile, it was found that the quantum efficiency of phosphor namely （Ca,Sr）7（SiO3）6Cl2：3 tool.% Dy3＋ 10 mol.% Euz＋ could get up to 24.6%. The synthesized yellow-emitting （Ca,Sr）7（SiO3）6C12：Dy3＋,Eu2＋ is a promising candidate as high-efficiency yellow phosphor for NUV-excited white LEDs.
基金supported by the State Key Development Program for Basic Research of China (Grant No. 2006CB601002)the National Natural Science Foundation of China (Grant No. 10734120)
文摘A series of big single crystals of BaFeFe2-xNixAs2 have been prepared by the FeAs self-flux method, with nominal nickel doping x = 0--0.12. The dimensions of the cleaved crystals are over 10~mm along ab plane and ～ 2~mm in maximum along the c direction. The measurements of x-ray diffraction, electrical resistance and magnetic property are carried out on the crystals. For the undoped parent compound BaFe2As2, both resistance and magnetization data display an anomaly associated with spin density wave and/or structural phase transition, with the transition temperatures at ～ 138~K. For Ni-doped BaFe2-xNixAs2 crystals, the superconducting critical temperature Tc ranges from 4.3~K for x=0.06 sample to 20~K for the optimally doped x=0.10 crystal.
