A novel self-recoverable mechanoluminescent phosphor Ca_(5)Ga_(6)O_(14)∶Eu^(3+) was developed by the high-tem-perature solid-state reaction method,and its luminescence properties were investigated.Ca_(5)Ga_(6)O_(14)...A novel self-recoverable mechanoluminescent phosphor Ca_(5)Ga_(6)O_(14)∶Eu^(3+) was developed by the high-tem-perature solid-state reaction method,and its luminescence properties were investigated.Ca_(5)Ga_(6)O_(14)∶Eu^(3+)can produce red mechanoluminescence,and importantly,it shows good repeatability.The mechanoluminescence of Ca_(5)Ga_(6)O_(14)∶Eu^(3+) results from the piezoelectric field generated inside the material under stress,rather than the charge carriers stored in the traps,which can be confirmed by the multiple cycles of mechanoluminescence tests and heat treatment tests.The mechanoluminescence color can be turned from red to green by co-doping varied concentrations of Tb^(3+),which may be meaningful for encrypted letter writing.The encryption scheme for secure communication was devised by harnessing mechanoluminescence patterns in diverse shapes and ASCII codes,which shows good encryption performance.The results suggest that the mechanoluminescence phosphor Ca_(5)Ga_(6)O_(14)∶Eu^(3+),Tb^(3+)may be applied to the optical information encryption.展开更多
A white emitting phosphor Ba2Ca(BO3)2:Dy3+ was synthesized via a high temperature solid state reaction at 1000℃ for 5 h. The luminescence, mole fraction quenching and thermal stability of Ba2Ca(BO3)2:Dy3+ were invest...A white emitting phosphor Ba2Ca(BO3)2:Dy3+ was synthesized via a high temperature solid state reaction at 1000℃ for 5 h. The luminescence, mole fraction quenching and thermal stability of Ba2Ca(BO3)2:Dy3+ were investigated. According to the phase composition analyzed by X-ray powder diffraction, there is no crystalline phase except Ba2Ca(BO3)2 in the sample. Ba2Ca(BO3)2:Dy3+ can produce white emission under 348 nm excitation. The emission intensities of Ba2Ca(BO3)2:Dy3+ are affected by Dy3+ concentration. The concentration quenching effect was analyzed, and the concentration quenching mechanism was verified as dipole-dipole interaction. The critical distance(R c) obtained based on the crystal structure data is 2.911 nm. At 150℃, the emission intensity of Ba2Ca(BO3)2:Dy3+ is 68.0% of the initial value at room temperature. The activation energy for the thermal quenching calculated is 0.202 e V. Moreover, the CIE chromaticity coordinates of Ba2Ca(BO3)2:Dy3+ locate in the white region of(0.319, 0.356).展开更多
A red emitting phosphor of Ba_3Eu(PO_4)_3:Tb^(3+) was synthesized by a solid state method. The energy transfer from Tb^(3+) to Eu3+ in Ba_3Eu(PO_4)_3:Tb^(3+) was proved by the spectral properties and decay curves. The...A red emitting phosphor of Ba_3Eu(PO_4)_3:Tb^(3+) was synthesized by a solid state method. The energy transfer from Tb^(3+) to Eu3+ in Ba_3Eu(PO_4)_3:Tb^(3+) was proved by the spectral properties and decay curves. The emission intensity of Ba_3Eu(PO_4)_3 is enhanced by doping Tb^(3+) as a sensitizer. For Ba_3Eu(PO_4)_3:Tb^(3+), the ~5D_3→~7F_J transition of Tb^(3+) occurs, and the corresponding emission intensities can be tuned when Tb^(3+) content increases, and the concentration quenching effect appears. However, for the ~5D_4→~7F_J transition of Tb^(3+), its intensity straight increases with increasing Tb^(3+) content. For Ba_3Eu(PO_4)_3:Tb^(3+), the values of CIE chromaticity coordinates are similar to those of commercial red phosphors of Sr_2Si_5N_8:Eu^(2+) and Y_2O_2S:Eu^(3+). The results indicate that this red emitting phosphor has a potential application for white LEDs.展开更多
A series of Yb^(3+)/Er^(3+) or Er^(3+) doped SrIn_2O_4 were synthesized by a high temperature solid state method.The up-conversion luminescence property and the phase formation of SrIn_2O_4:Er^(3+) and SrIn_2O_4:Yb^(3...A series of Yb^(3+)/Er^(3+) or Er^(3+) doped SrIn_2O_4 were synthesized by a high temperature solid state method.The up-conversion luminescence property and the phase formation of SrIn_2O_4:Er^(3+) and SrIn_2O_4:Yb^(3+),Er^(3+) were investigated by X-ray diffraction(XRD) and spectral methods.The XRD pattern shows that incorporating different amounts of Yb^(3+)and Er^(3+) have no influence on the phase formation of SrIn_2O_4.The up-conversion luminescence spectrum of SrIn_2O_4:Er^(3+) presented a weak luminescence due to ground state absorption of Er^(3+).However,Yb^(3+)/Er^(3+) codoped SrIn_2O_4 depicted the green(525 and 551 run) and red(662 nm) up-conversion luminescence which were assigned to the energy transfer from the Yb^(3+) transition ~2F_(7/2)-~2F_(5/2) to the Er^(3+) transitions ~2H_(11/2)-~4I_(15/2) and ~4F_(9/2-~4I_(15/2),respectively.The possible up-conversion luminescence mechanism of SrIn_2O_4:Yb^(3+),Er^(3+) was analyzed.All results could be helpful to the development of up-conversion luminescence materials.展开更多
A series of Sm^(3+) doped KMgLa(PO_4)_2 have been prepared via a high-temperature solid-state method.The phase of the phosphor was characterized by X-ray diffraction,and the spectra of phosphors were measured by the f...A series of Sm^(3+) doped KMgLa(PO_4)_2 have been prepared via a high-temperature solid-state method.The phase of the phosphor was characterized by X-ray diffraction,and the spectra of phosphors were measured by the fluorescence spectrophotometer.Under 402 nm near-ultraviolet excitation,KMgLa(PPO_4)_2:Sm^(3+) shows orange-red emission,and the emission peak locates at 600 nm,which is associated to the ~4G_(2/5)→~6H_(9/2) transition of Sm^(3+).The emission intensity of phosphors can be tuned by changing the Sm^(3+) concentration,and the optimal Sm^(3+) doping concentration is about0.01.The concentration quenching phenomenon was observed in KMgLa(PO_4)_2:Sm^(3+),and the critical distance is calculated to be about 3.082 nm.The CIE chromaticity coordinates of phosphors shift from red to pink with the Sm^(3+) concentration increasing.All the results suggest that it could be a potential application in white LEDs manufacture.展开更多
文摘A novel self-recoverable mechanoluminescent phosphor Ca_(5)Ga_(6)O_(14)∶Eu^(3+) was developed by the high-tem-perature solid-state reaction method,and its luminescence properties were investigated.Ca_(5)Ga_(6)O_(14)∶Eu^(3+)can produce red mechanoluminescence,and importantly,it shows good repeatability.The mechanoluminescence of Ca_(5)Ga_(6)O_(14)∶Eu^(3+) results from the piezoelectric field generated inside the material under stress,rather than the charge carriers stored in the traps,which can be confirmed by the multiple cycles of mechanoluminescence tests and heat treatment tests.The mechanoluminescence color can be turned from red to green by co-doping varied concentrations of Tb^(3+),which may be meaningful for encrypted letter writing.The encryption scheme for secure communication was devised by harnessing mechanoluminescence patterns in diverse shapes and ASCII codes,which shows good encryption performance.The results suggest that the mechanoluminescence phosphor Ca_(5)Ga_(6)O_(14)∶Eu^(3+),Tb^(3+)may be applied to the optical information encryption.
文摘A white emitting phosphor Ba2Ca(BO3)2:Dy3+ was synthesized via a high temperature solid state reaction at 1000℃ for 5 h. The luminescence, mole fraction quenching and thermal stability of Ba2Ca(BO3)2:Dy3+ were investigated. According to the phase composition analyzed by X-ray powder diffraction, there is no crystalline phase except Ba2Ca(BO3)2 in the sample. Ba2Ca(BO3)2:Dy3+ can produce white emission under 348 nm excitation. The emission intensities of Ba2Ca(BO3)2:Dy3+ are affected by Dy3+ concentration. The concentration quenching effect was analyzed, and the concentration quenching mechanism was verified as dipole-dipole interaction. The critical distance(R c) obtained based on the crystal structure data is 2.911 nm. At 150℃, the emission intensity of Ba2Ca(BO3)2:Dy3+ is 68.0% of the initial value at room temperature. The activation energy for the thermal quenching calculated is 0.202 e V. Moreover, the CIE chromaticity coordinates of Ba2Ca(BO3)2:Dy3+ locate in the white region of(0.319, 0.356).
文摘A red emitting phosphor of Ba_3Eu(PO_4)_3:Tb^(3+) was synthesized by a solid state method. The energy transfer from Tb^(3+) to Eu3+ in Ba_3Eu(PO_4)_3:Tb^(3+) was proved by the spectral properties and decay curves. The emission intensity of Ba_3Eu(PO_4)_3 is enhanced by doping Tb^(3+) as a sensitizer. For Ba_3Eu(PO_4)_3:Tb^(3+), the ~5D_3→~7F_J transition of Tb^(3+) occurs, and the corresponding emission intensities can be tuned when Tb^(3+) content increases, and the concentration quenching effect appears. However, for the ~5D_4→~7F_J transition of Tb^(3+), its intensity straight increases with increasing Tb^(3+) content. For Ba_3Eu(PO_4)_3:Tb^(3+), the values of CIE chromaticity coordinates are similar to those of commercial red phosphors of Sr_2Si_5N_8:Eu^(2+) and Y_2O_2S:Eu^(3+). The results indicate that this red emitting phosphor has a potential application for white LEDs.
文摘A series of Yb^(3+)/Er^(3+) or Er^(3+) doped SrIn_2O_4 were synthesized by a high temperature solid state method.The up-conversion luminescence property and the phase formation of SrIn_2O_4:Er^(3+) and SrIn_2O_4:Yb^(3+),Er^(3+) were investigated by X-ray diffraction(XRD) and spectral methods.The XRD pattern shows that incorporating different amounts of Yb^(3+)and Er^(3+) have no influence on the phase formation of SrIn_2O_4.The up-conversion luminescence spectrum of SrIn_2O_4:Er^(3+) presented a weak luminescence due to ground state absorption of Er^(3+).However,Yb^(3+)/Er^(3+) codoped SrIn_2O_4 depicted the green(525 and 551 run) and red(662 nm) up-conversion luminescence which were assigned to the energy transfer from the Yb^(3+) transition ~2F_(7/2)-~2F_(5/2) to the Er^(3+) transitions ~2H_(11/2)-~4I_(15/2) and ~4F_(9/2-~4I_(15/2),respectively.The possible up-conversion luminescence mechanism of SrIn_2O_4:Yb^(3+),Er^(3+) was analyzed.All results could be helpful to the development of up-conversion luminescence materials.
文摘A series of Sm^(3+) doped KMgLa(PO_4)_2 have been prepared via a high-temperature solid-state method.The phase of the phosphor was characterized by X-ray diffraction,and the spectra of phosphors were measured by the fluorescence spectrophotometer.Under 402 nm near-ultraviolet excitation,KMgLa(PPO_4)_2:Sm^(3+) shows orange-red emission,and the emission peak locates at 600 nm,which is associated to the ~4G_(2/5)→~6H_(9/2) transition of Sm^(3+).The emission intensity of phosphors can be tuned by changing the Sm^(3+) concentration,and the optimal Sm^(3+) doping concentration is about0.01.The concentration quenching phenomenon was observed in KMgLa(PO_4)_2:Sm^(3+),and the critical distance is calculated to be about 3.082 nm.The CIE chromaticity coordinates of phosphors shift from red to pink with the Sm^(3+) concentration increasing.All the results suggest that it could be a potential application in white LEDs manufacture.
