The emission and the excitation spectra of GdPO4 ： Eu^3＋ and GdBO3： Eu^3 ＋ prepared by solid state reaction method were investigated using the synchrotron radiation source of SUPERLUMI station of HASYLAB. The ener...The emission and the excitation spectra of GdPO4 ： Eu^3＋ and GdBO3： Eu^3 ＋ prepared by solid state reaction method were investigated using the synchrotron radiation source of SUPERLUMI station of HASYLAB. The energy transfer between Gd^3＋ and Eu^3＋ was discussed with the probability of quantum cutting process. In the excitation spectra monitoring the red emission from Eu^3＋ , the distinct lines corresponding to the intraconfigurational 4f-4f transitions from Gd^3＋ were observed for both samples, indicating an efficient energy transfer from host Gd^3＋ ions to the doped Eu^3＋ ions. The efficient energy transfer is necessary for the quantum cutting process based on the two-step energy transfer from Gd^3＋ to Eu^3＋ . However, the overlapping of the lines corresponding to Gd^3＋ ：^8S7/2→^6GJ and the broad excitation band （180 - 270 nm） due to Eu^3＋- O^2- charge transfer states （CTS） around 200 nm cause excitation energy on ^6GJ levels to dissipate into CTS by direct energy transfer, unfavorable to the cross relaxation energy transfer between Gd^3＋ and Eu^3＋, thus unfavorable to the quantum cutting process. With the help of the general rules governing the energy positions of Eu^3＋-O^2- ：CTS, the suggestions concerning searching suitable oxide hosts for Gd^3＋-Eu^3＋ quantum cutting were made.展开更多
Polycrystal of GdPO_(4):RE^(3+)(RE=Tb,Tm)phosphors were prepared by solid-state method.Vacuum ultraviolet excitation and emission spectrum and the energy transfer mechanism between the host and dopants of Tb^(3+)and T...Polycrystal of GdPO_(4):RE^(3+)(RE=Tb,Tm)phosphors were prepared by solid-state method.Vacuum ultraviolet excitation and emission spectrum and the energy transfer mechanism between the host and dopants of Tb^(3+)and Tm^(3+)were investigated respectively.The emission of Gd^(3+)at 313 nm was enhanced by the strong absorption of CTS of Tm^(3+)at 180 nm in GdPO_(4):Tm.It has also been concluded that the excitation of Gd^(3+)is transferred to Tb^(3+)and then emission peaks of^(5)D_(J)→^(7)F_(J)of Tb^(3+)were observed.展开更多
Molten calcium-magnesium-alumina-silicate(CMAS)is easy to wet and penetrates into thermal barrier coatings(TBCs),causing coating corrosion and premature failure.The application of a protective layer on the TBC surface...Molten calcium-magnesium-alumina-silicate(CMAS)is easy to wet and penetrates into thermal barrier coatings(TBCs),causing coating corrosion and premature failure.The application of a protective layer on the TBC surface is considered a useful method to alleviate CMAS attack.In this study,a bilayer-structured apatite layer was developed,on which molten CMAS has low wettability.It had an acicular upper layer and a compact lower layer,which was constructed by pre-reacting GdPO4 with CMAS powders through precise regulation of the pre-reaction temperature,time,and CMAS concentration.The microstructure integrity of the bilayer-structured apatite layer remained intact after heat treatment at 1250℃ for 50 h,and the layer did not crack after 100 thermal cycles.When exposed to CMAS at 1250℃ for 20 h,the layer retained an intact structure and still functioned to prevent CMAS penetration.At 1250℃ for 30 min,the CMAS contact angle on the bilayer-structured apatite layer was 17.4°,which was three times greater than that on Gd2Zr2O7,which is another promising CMAS-resistant TBC material.Hence,the bilayer-structured apatite layer is quite attractive for addressing the CMAS issue of TBCs.展开更多
文摘The emission and the excitation spectra of GdPO4 ： Eu^3＋ and GdBO3： Eu^3 ＋ prepared by solid state reaction method were investigated using the synchrotron radiation source of SUPERLUMI station of HASYLAB. The energy transfer between Gd^3＋ and Eu^3＋ was discussed with the probability of quantum cutting process. In the excitation spectra monitoring the red emission from Eu^3＋ , the distinct lines corresponding to the intraconfigurational 4f-4f transitions from Gd^3＋ were observed for both samples, indicating an efficient energy transfer from host Gd^3＋ ions to the doped Eu^3＋ ions. The efficient energy transfer is necessary for the quantum cutting process based on the two-step energy transfer from Gd^3＋ to Eu^3＋ . However, the overlapping of the lines corresponding to Gd^3＋ ：^8S7/2→^6GJ and the broad excitation band （180 - 270 nm） due to Eu^3＋- O^2- charge transfer states （CTS） around 200 nm cause excitation energy on ^6GJ levels to dissipate into CTS by direct energy transfer, unfavorable to the cross relaxation energy transfer between Gd^3＋ and Eu^3＋, thus unfavorable to the quantum cutting process. With the help of the general rules governing the energy positions of Eu^3＋-O^2- ：CTS, the suggestions concerning searching suitable oxide hosts for Gd^3＋-Eu^3＋ quantum cutting were made.
基金supported by the Natural Science Foundation of Tianjin City(Grant No.033601111).
文摘Polycrystal of GdPO_(4):RE^(3+)(RE=Tb,Tm)phosphors were prepared by solid-state method.Vacuum ultraviolet excitation and emission spectrum and the energy transfer mechanism between the host and dopants of Tb^(3+)and Tm^(3+)were investigated respectively.The emission of Gd^(3+)at 313 nm was enhanced by the strong absorption of CTS of Tm^(3+)at 180 nm in GdPO_(4):Tm.It has also been concluded that the excitation of Gd^(3+)is transferred to Tb^(3+)and then emission peaks of^(5)D_(J)→^(7)F_(J)of Tb^(3+)were observed.
基金the Innovation Project(No.D925BCD)the National Natural Science Foundation of China(Nos.52471087 and 52272070)the National Science and Technology Major Project(No.J2022-VI0009-0040).
文摘Molten calcium-magnesium-alumina-silicate(CMAS)is easy to wet and penetrates into thermal barrier coatings(TBCs),causing coating corrosion and premature failure.The application of a protective layer on the TBC surface is considered a useful method to alleviate CMAS attack.In this study,a bilayer-structured apatite layer was developed,on which molten CMAS has low wettability.It had an acicular upper layer and a compact lower layer,which was constructed by pre-reacting GdPO4 with CMAS powders through precise regulation of the pre-reaction temperature,time,and CMAS concentration.The microstructure integrity of the bilayer-structured apatite layer remained intact after heat treatment at 1250℃ for 50 h,and the layer did not crack after 100 thermal cycles.When exposed to CMAS at 1250℃ for 20 h,the layer retained an intact structure and still functioned to prevent CMAS penetration.At 1250℃ for 30 min,the CMAS contact angle on the bilayer-structured apatite layer was 17.4°,which was three times greater than that on Gd2Zr2O7,which is another promising CMAS-resistant TBC material.Hence,the bilayer-structured apatite layer is quite attractive for addressing the CMAS issue of TBCs.
