To explore suitable single-phase white emission phosphors for warm white light emitting diodes, a series of novel phosphors Na3MgZr（PO4）3：xDy^3＋（0 ≤ x ≤ 0.03） is prepared, and their phase purities as well as p...To explore suitable single-phase white emission phosphors for warm white light emitting diodes, a series of novel phosphors Na3MgZr（PO4）3：xDy^3＋（0 ≤ x ≤ 0.03） is prepared, and their phase purities as well as photoluminescence properties are discussed in depth via x-ray diffraction structure refinement and photoluminescence spectrum measurement.The electronic structure properties of the Na3MgZr（PO4）3host are calculated. The results reveal that Na3MgZr（PO4）3 possesses a direct band gap with a band gap value of 4.917 eV. The obtained Na3MgZr（PO4）3：Dy^3＋ phosphors are all well crystallized in trigonal structure with space group Rc, which has strong absorption around 365 nm and can generate warm white light emissions peaking at 487, 576, and 673 nm upon ultraviolet excitation, which are attributed to the transitions from -4F9/2 to ^6H15/2,^6H13/2, and ^6H11/2 of Dy^3＋ ions, respectively. The optimal doping content, critical distance, decay time, and Commission International de L＇Eclairage（CIE） chromaticity coordinates are investigated in Dy^3＋ ion-doped Na3MgZr（PO4）3. The thermal quenching analysis shows that Na3MgZr（PO4）3：Dy^3＋ has a good thermal stability, and the thermal activation energy is calculated. The performances of Na3MgZr（PO4）3：Dy^3＋ make it a potential single-phase white emission phosphor for warm white light emitting diode.展开更多
A Yb_（0.11）Gd_（0.89）Ca_4O（BO_3）_3 crystal with new composition was grown by the Czochralski method. The crystal structure was measured and analyzed. The unit-cell parameters of the Yb_（0.11）Gd_（0.89）COB were...A Yb_（0.11）Gd_（0.89）Ca_4O（BO_3）_3 crystal with new composition was grown by the Czochralski method. The crystal structure was measured and analyzed. The unit-cell parameters of the Yb_（0.11）Gd_（0.89）COB were calculated to be a=0.8089（7） nm, b=1.5987（6） nm, c=0.3545（8） nm, β=101.22o. The absorption and fluorescence spectra were measured. The maximum absorption cross-section of Yb_（0.11）Gd_（0.89） COB crystal was 0.79×10^（–20）cm^2, which occurred at 976 nm with Y polarization. The emission cross-section at 1027 nm was calculated to be 0.33×10^（–20） cm^2. The radiative lifetime trad was calculated to be 2.74 ms. The Stark energy-level diagram of Yb^（3＋）in the Yb_（0.11）Gd_（0.89）COB crystal field at room temperature was determined. The ground-state energy level ~2F_（7/2） splitting was calculated to be as large as 1004 cm^（–1） and the zero-line energy was 10246 cm^（–1）. A maximum output power of 9.35 W was achieved in continuous-wave（CW） mode, with the slope efficiency being 42.1%. Chemical etching experiment revealed that the dominating imperfections in the studied Yb_（0.11）Gd_（0.89） COB crystal were dislocations and sub-grain boundaries. The existence of crystal defects could cause light scattering, and degrade laser output efficiency. The influence of crystal defects on laser properties was discussed.展开更多
基金Project supported by the Doctoral Research Fund of Liaoning Province,China(Grant No.201601351)the National Natural Science Foundation of China(Grant No.51502142)the General Program of Natural Science Foundation of the Jiangsu Provincial Higher Education Institutions,China(Grant No.15KJB430021)
文摘To explore suitable single-phase white emission phosphors for warm white light emitting diodes, a series of novel phosphors Na3MgZr（PO4）3：xDy^3＋（0 ≤ x ≤ 0.03） is prepared, and their phase purities as well as photoluminescence properties are discussed in depth via x-ray diffraction structure refinement and photoluminescence spectrum measurement.The electronic structure properties of the Na3MgZr（PO4）3host are calculated. The results reveal that Na3MgZr（PO4）3 possesses a direct band gap with a band gap value of 4.917 eV. The obtained Na3MgZr（PO4）3：Dy^3＋ phosphors are all well crystallized in trigonal structure with space group Rc, which has strong absorption around 365 nm and can generate warm white light emissions peaking at 487, 576, and 673 nm upon ultraviolet excitation, which are attributed to the transitions from -4F9/2 to ^6H15/2,^6H13/2, and ^6H11/2 of Dy^3＋ ions, respectively. The optimal doping content, critical distance, decay time, and Commission International de L＇Eclairage（CIE） chromaticity coordinates are investigated in Dy^3＋ ion-doped Na3MgZr（PO4）3. The thermal quenching analysis shows that Na3MgZr（PO4）3：Dy^3＋ has a good thermal stability, and the thermal activation energy is calculated. The performances of Na3MgZr（PO4）3：Dy^3＋ make it a potential single-phase white emission phosphor for warm white light emitting diode.
基金Project supported by National Natural Science Foundation of China(11204148,11374170)Taishan Scholar Program of Shandong Province+2 种基金Open Project of State Key Laboratory of Rare Earth Resource Utilization(RERU2016015)the Applied Basic Research Programs for Youths of Qingdao(15-9-1-52-JCH)Qingdao Postdoctoral Application Research Project(2015127)
文摘A Yb_（0.11）Gd_（0.89）Ca_4O（BO_3）_3 crystal with new composition was grown by the Czochralski method. The crystal structure was measured and analyzed. The unit-cell parameters of the Yb_（0.11）Gd_（0.89）COB were calculated to be a=0.8089（7） nm, b=1.5987（6） nm, c=0.3545（8） nm, β=101.22o. The absorption and fluorescence spectra were measured. The maximum absorption cross-section of Yb_（0.11）Gd_（0.89） COB crystal was 0.79×10^（–20）cm^2, which occurred at 976 nm with Y polarization. The emission cross-section at 1027 nm was calculated to be 0.33×10^（–20） cm^2. The radiative lifetime trad was calculated to be 2.74 ms. The Stark energy-level diagram of Yb^（3＋）in the Yb_（0.11）Gd_（0.89）COB crystal field at room temperature was determined. The ground-state energy level ~2F_（7/2） splitting was calculated to be as large as 1004 cm^（–1） and the zero-line energy was 10246 cm^（–1）. A maximum output power of 9.35 W was achieved in continuous-wave（CW） mode, with the slope efficiency being 42.1%. Chemical etching experiment revealed that the dominating imperfections in the studied Yb_（0.11）Gd_（0.89） COB crystal were dislocations and sub-grain boundaries. The existence of crystal defects could cause light scattering, and degrade laser output efficiency. The influence of crystal defects on laser properties was discussed.
