Recently,how to employ a feasible strategy to design novel phosphors with color-tuning properties and enhanced photoemission has become a hot research subject.Herein,we report a series of UV-converted Eu^(3+),Bi^(3+)-...Recently,how to employ a feasible strategy to design novel phosphors with color-tuning properties and enhanced photoemission has become a hot research subject.Herein,we report a series of UV-converted Eu^(3+),Bi^(3+)-doped La_(2)MgGeO_(6)phosphors,which enable broad color tuning and Eu^(3+)-related fluorescence enhancement simultaneously.Structural analysis shows that all samples crystallize in a trigonal structure with the space group R_(3)(no.146),and Eu^(3+)and Bi^(3+)ions tend to substitute La^(3+)ions rather than Mg^(2+)and Ge^(4+)ions.Photoluminescence(PL)results show that excitation in the UV spectral region(e.g.,248 nm,292 nm,and 393 nm)enables the Bi^(3+)-doped La_(2)MgGeO_(6)phosphors to exhibit a single blue emission band(i.e.,412 nm)that corresponds to the characteristic^(3)P_(1)→^(1)S_(0)transition of Bi^(3+)ions and Eu^(3+)-doped La_(2)MgGeO_(6)phosphors to show sharp emission lines that correspond to the characteristic^(5)D_(0)→^(7)F_(J)(J=1,2,3,and 4)transitions of Eu^(3+)ions.In addition,we studied the energy transfer mechanism from Bi^(3+)to Eu^(3+)ions,and on the basis of the PL results and theoretical evaluations,we revealed that this energy transfer process occurred via a dipole-quadrupole(d-q)interaction and could enhance Eu^(3+)-related fluorescence intensity and thus led to color tuning from blue to red upon excitation at 298 nm.To illustrate our experimental PL observations more clearly,a mechanistic profile based on the energy transfer and simplified spectral energy levels of Bi^(3+)and Eu^(3+)ions is also established.This study not only adds a new member into the family of UV-converted tunable phosphors,but also provides new insights into the discovery of more single-phase phosphors with simultaneous PL enhancement and emission color tuning for UV-converted wLEDs using the energy transfer interaction.展开更多
基金financial support received from the Natural Science Foundation of China(No.11747074)Guangdong Province Science and Technology Plan Project Public Welfare Fund and Ability Construction Project(2016A010103041,2017A010103025)+2 种基金Doctoral Program of Lingnan Normal University(ZL1503)Zhanjiang Science and Technology Plan Project(2017A03021)Natural Science Foundation of Guangdong(2016A030313670).
文摘Recently,how to employ a feasible strategy to design novel phosphors with color-tuning properties and enhanced photoemission has become a hot research subject.Herein,we report a series of UV-converted Eu^(3+),Bi^(3+)-doped La_(2)MgGeO_(6)phosphors,which enable broad color tuning and Eu^(3+)-related fluorescence enhancement simultaneously.Structural analysis shows that all samples crystallize in a trigonal structure with the space group R_(3)(no.146),and Eu^(3+)and Bi^(3+)ions tend to substitute La^(3+)ions rather than Mg^(2+)and Ge^(4+)ions.Photoluminescence(PL)results show that excitation in the UV spectral region(e.g.,248 nm,292 nm,and 393 nm)enables the Bi^(3+)-doped La_(2)MgGeO_(6)phosphors to exhibit a single blue emission band(i.e.,412 nm)that corresponds to the characteristic^(3)P_(1)→^(1)S_(0)transition of Bi^(3+)ions and Eu^(3+)-doped La_(2)MgGeO_(6)phosphors to show sharp emission lines that correspond to the characteristic^(5)D_(0)→^(7)F_(J)(J=1,2,3,and 4)transitions of Eu^(3+)ions.In addition,we studied the energy transfer mechanism from Bi^(3+)to Eu^(3+)ions,and on the basis of the PL results and theoretical evaluations,we revealed that this energy transfer process occurred via a dipole-quadrupole(d-q)interaction and could enhance Eu^(3+)-related fluorescence intensity and thus led to color tuning from blue to red upon excitation at 298 nm.To illustrate our experimental PL observations more clearly,a mechanistic profile based on the energy transfer and simplified spectral energy levels of Bi^(3+)and Eu^(3+)ions is also established.This study not only adds a new member into the family of UV-converted tunable phosphors,but also provides new insights into the discovery of more single-phase phosphors with simultaneous PL enhancement and emission color tuning for UV-converted wLEDs using the energy transfer interaction.
