We investigated the emission properties of Eu^(3+)-doped GdNbO_(4)-based oxide phosphors,aiming at improving the Eu^(3+)emission by codoping of Bi^(3+)and Li^(+).Eu^(3+)singly doped,Eu^(3+)and Bi^(3+)doubly doped,and ...We investigated the emission properties of Eu^(3+)-doped GdNbO_(4)-based oxide phosphors,aiming at improving the Eu^(3+)emission by codoping of Bi^(3+)and Li^(+).Eu^(3+)singly doped,Eu^(3+)and Bi^(3+)doubly doped,and Eu^(3+),Bi^(3+),and Li^(+)triply doped GdNbO_(4)were prepared using a high-temperature solid-state reaction method.The red-orange emissions from Eu^(3+)in the singly doped samples are significantly improved by the codoping of Bi^(3+),mainly due to the energy transfer from Bi^(3+)to Eu^(3+).The additional codoping of Li^(+)is found to increase the Eu^(3+)emission significantly.This improvement might be attributed to the increase in the photoluminescent quantum yield originating from larger grain sizes and better crystallinity.A detailed analysis of the X-ray diffraction pattern and the asymmetric ratio estimated from the photoluminescence spectra show that the local lattice environment around Eu^(3+)in GdNbO_(4)does not change significantly with the codoping of Bi^(3+)and Li^(+).Our results indicate that Li^(+)doping is a promising way to improve the emission properties of rare-earth ion-doped GdNbO_(4)phosphors.展开更多
A quantum spin liquid (QSL) is an exotic quantum ground state that does not break conventional symmetries and where the spins in the system remain dynamic down to zero temperature. Unlike a trivial paramagnetic state,...A quantum spin liquid (QSL) is an exotic quantum ground state that does not break conventional symmetries and where the spins in the system remain dynamic down to zero temperature. Unlike a trivial paramagnetic state, it features long-range quantum entanglement and supports fractionalized excitations.展开更多
In this study,the upconversion(UC)emissions of Er3+and Yb3+co-doped SrZrO3 nanocrystals(NCs)were investigated in terms of the thermal annealing temperature and concentration of Er3+ions and compared with the emissions...In this study,the upconversion(UC)emissions of Er3+and Yb3+co-doped SrZrO3 nanocrystals(NCs)were investigated in terms of the thermal annealing temperature and concentration of Er3+ions and compared with the emissions under a near-ultraviolet(near-UV)excitation.The NCs were synthesized by the combustion method,and the as-synthesized NCs were post-annealed at high temperatures.The X-ray diffraction patterns revealed that the grain sizes and crystallinity degrees of the samples increased with increasing annealing temperatures.The photoluminescence spectra of our samples exhibited strong green and very weak red emissions with the near-UV excitation,originating from the f-f transitions in the Er3+ions.Interestingly,under near-infrared(near-IR)excitation,we identified sizable visible emissions at 525,547,and 660 nm in our NCs,which indicated that the UC process successfully occurred in our NCs.These UC emissions were maximized in the NCs with an Er3+concentration of 0.02 and thermal annealing at 1000°C.We found that the intensity ratios of red to green emissions increased with increasing annealing temperatures.We discussed the differences in the emissions between near-UV and near-IR excitations.展开更多
基金Project supported by the Basic Science Research Program through the National Research Foundation of Korea(NRF)funded by the Ministry of Education(NRF-2021R1A6A1A10044154)。
文摘We investigated the emission properties of Eu^(3+)-doped GdNbO_(4)-based oxide phosphors,aiming at improving the Eu^(3+)emission by codoping of Bi^(3+)and Li^(+).Eu^(3+)singly doped,Eu^(3+)and Bi^(3+)doubly doped,and Eu^(3+),Bi^(3+),and Li^(+)triply doped GdNbO_(4)were prepared using a high-temperature solid-state reaction method.The red-orange emissions from Eu^(3+)in the singly doped samples are significantly improved by the codoping of Bi^(3+),mainly due to the energy transfer from Bi^(3+)to Eu^(3+).The additional codoping of Li^(+)is found to increase the Eu^(3+)emission significantly.This improvement might be attributed to the increase in the photoluminescent quantum yield originating from larger grain sizes and better crystallinity.A detailed analysis of the X-ray diffraction pattern and the asymmetric ratio estimated from the photoluminescence spectra show that the local lattice environment around Eu^(3+)in GdNbO_(4)does not change significantly with the codoping of Bi^(3+)and Li^(+).Our results indicate that Li^(+)doping is a promising way to improve the emission properties of rare-earth ion-doped GdNbO_(4)phosphors.
文摘A quantum spin liquid (QSL) is an exotic quantum ground state that does not break conventional symmetries and where the spins in the system remain dynamic down to zero temperature. Unlike a trivial paramagnetic state, it features long-range quantum entanglement and supports fractionalized excitations.
基金This research was supported by the Basic Science Research Program through the National Research Foundation of Korea(NRF),funded by the Ministry of Science,ICT,and Future Planning(NRF-2018R1D1A1A02086130).
文摘In this study,the upconversion(UC)emissions of Er3+and Yb3+co-doped SrZrO3 nanocrystals(NCs)were investigated in terms of the thermal annealing temperature and concentration of Er3+ions and compared with the emissions under a near-ultraviolet(near-UV)excitation.The NCs were synthesized by the combustion method,and the as-synthesized NCs were post-annealed at high temperatures.The X-ray diffraction patterns revealed that the grain sizes and crystallinity degrees of the samples increased with increasing annealing temperatures.The photoluminescence spectra of our samples exhibited strong green and very weak red emissions with the near-UV excitation,originating from the f-f transitions in the Er3+ions.Interestingly,under near-infrared(near-IR)excitation,we identified sizable visible emissions at 525,547,and 660 nm in our NCs,which indicated that the UC process successfully occurred in our NCs.These UC emissions were maximized in the NCs with an Er3+concentration of 0.02 and thermal annealing at 1000°C.We found that the intensity ratios of red to green emissions increased with increasing annealing temperatures.We discussed the differences in the emissions between near-UV and near-IR excitations.
