摘要
Here,we report a series of Bi^(3+)-doped Ba_(2)Y_(1-x)Sc_(x)NbO_(6)(0≤x≤1.0 mol)phosphors by using the traditional high temperature solid-state reaction.To achieve the structural and photoluminescent(PL)information,several experimental characterizations and theoretical calculations were carried out,including X-ray diffraction(XRD),Rietveld refinement,UV-visible diffuse reflectance and PL spectra,temperature dependent PL spectra,and density functional theo retical(DFT)calculations.The XRD results show that the Bi^(3+)-doped Ba_(2)Y_(1-x)Sc_(x)NbO_(6)samples belong to the double-perovskite phase with a cubic space group of Fm3 m,and the diffraction positions shift toward high diffraction angle when the larger Y^(3+)ions are gradually replaced by the smaller Sc^(3+)ions.In addition,the refined XRD findings show that the Bi^(3+)ions tend to substitute the Y^(3+)and Sc^(3+)sites in the Bi^(3+)-doped Ba_(2)Y_(1-x)Sc_(x)NbO_(6)0<x<1.0 mol)solid solutions.The PL spectra show that the emission positions of the solid solution samples tune from446 to 497 nm with the increase of Sc^(3+) content,which can be attributed to the modification of crystal field strength around Bi^(3+)ions.Moreover,there is energy transfer from the Ba_(2)YNbO_(6)host to Bi^(3+)ions,which is dominated by a resonant type via a dipole-quadrupole(d-q)interaction.The Ba_(2)Y_(0.6)Sc_(0.4)NbO_(6):0.02 molBi^(3+)shows the strongest PL intensity under 365 nm excitation,with the best quantum efficiency(QE)of 68%,and it keeps 60%of the room temperature emission intensity when the temperature increases to 150℃,meaning that the Ba_(2)Y_(0.6)Sc_(0.4)NbO_(6):Bi^(3+)features excellent thermal quenching of luminescence.By combining this optimal sample with a commercial red-emitting Sr_(2)Si_(5)N_(8):Eu^(2+)phosphor,and a commercial 365 nm UV LED chip,a white LED device,with the color temperature(CT)of 3678 K,color rendering index(CRI)of 67.9,and CIE coordinates at(0.371,0.376),is achieved.
基金
Project supported by the Key R&D Project of Hebei Province(18214321)
the Research Foundation of Hengshui University for High-level Talents(2019GC10)
National Innovation and Entrepreneurship Training Program for College Students(202010101001)
the Science Technology Program of Hengshui city(2018011002Z)。
