The photoluminescence (PL) characteristics of hybrid β-FeSi2/Si and pure β-FeSi2 films fabricated by pulsed laser deposition at 20 K are investigated. The intensity of the 1.54-μm PL from the former is enhanced, ...The photoluminescence (PL) characteristics of hybrid β-FeSi2/Si and pure β-FeSi2 films fabricated by pulsed laser deposition at 20 K are investigated. The intensity of the 1.54-μm PL from the former is enhanced, but the enhancement vanishes when the excitation wavelength is larger than the widened band gap of Si nanocrystal. Time-resolved PL decay measurements reveal that the lifetime of the photo-excited carriers in the hybrid β-FeSi2/Si film is longer than that in the pure β-FeSi2 film, providing evidence that the PL enhancement results from the resonant charge transfer from nanocrystalline Si to β-FeSi2.展开更多
We investigate the electronic structure and magnetic properties of layered compound Sr_(3)Fe_(2)O_(5) based on firstprinciples calculations in the framework of density functional theory with GGA+U method.Under high pr...We investigate the electronic structure and magnetic properties of layered compound Sr_(3)Fe_(2)O_(5) based on firstprinciples calculations in the framework of density functional theory with GGA+U method.Under high pressure,the ladder-type layered structure of Sr_(3)Fe_(2)O_(5) is transformed into the infinite layered structure accompanied by a transition from G-type anti-ferromagnetic(AFM)insulator to ferromagnetic(FM)metal and a spin transition from S=2 to S=1.We reproduce these transformations in our calculations and give a clear physical interpretation.展开更多
A series of tunable phosphors NaAlSiO_4:Ce^(3+),Sm^(3+) were synthesized using a conventional high-temperature, solid-state method. Crystal structure, photoluminescence excitation, and emission spectra with flu...A series of tunable phosphors NaAlSiO_4:Ce^(3+),Sm^(3+) were synthesized using a conventional high-temperature, solid-state method. Crystal structure, photoluminescence excitation, and emission spectra with fluorescence decay curves were investigated. Under UV excitation(325 nm), NaAlSiO_4:Ce^(3+),Sm^(3+) showed strong blue emission located at 444 nm and orange-reddish emission centered at 563, 601, 648 and 712 nm, stemming from the characteristic emission for 4f-5d transition of Ce^(3+) and ~4G_(5/2)→~6H_J(J=5/2, 7/2, 9/2, 11/2) transition of Sm^(3+), respectively. In addition, we studied the detailed energy transfer process between Ce^(3+) and Sm^(3+) and found that it belonged to dipole-dipole resonance energy transfer. Furthermore, we noted that the white light emitting from the Ce^(3+), Sm^(3+) co-doped phosphors with the color coordinate(x=0.313, y=0.283) could be observed under 325 nm excitation, which was close to the ideal white light(x=0.33, y=0.33). The results indicated that this phosphor has a potential application as a single-phased alumino-silicate phosphor for ultraviolet white light-emitting diodes(UV-WLEDs).展开更多
基金Project supported by the National Basic Research Program of China(Grant Nos.2011CB922102 and 2013CB932901)the National Natural Science Foundation of China(Grant No.60976063)the Priority Academic Program Development(PAPD)of Higher Education Institutions of Jiangsu Province and HongKong Research Grants Council(RGC)General Research Funds(GRF)(Grant Nos.CityU 112510 and CityU 112212)
文摘The photoluminescence (PL) characteristics of hybrid β-FeSi2/Si and pure β-FeSi2 films fabricated by pulsed laser deposition at 20 K are investigated. The intensity of the 1.54-μm PL from the former is enhanced, but the enhancement vanishes when the excitation wavelength is larger than the widened band gap of Si nanocrystal. Time-resolved PL decay measurements reveal that the lifetime of the photo-excited carriers in the hybrid β-FeSi2/Si film is longer than that in the pure β-FeSi2 film, providing evidence that the PL enhancement results from the resonant charge transfer from nanocrystalline Si to β-FeSi2.
基金Project supported by the National Natural Science Foundation of China(Grant No.11964039)Xinjiang“Hundred Young Doctors Introduction Program”Project,China(Grant No.3010010111).
文摘We investigate the electronic structure and magnetic properties of layered compound Sr_(3)Fe_(2)O_(5) based on firstprinciples calculations in the framework of density functional theory with GGA+U method.Under high pressure,the ladder-type layered structure of Sr_(3)Fe_(2)O_(5) is transformed into the infinite layered structure accompanied by a transition from G-type anti-ferromagnetic(AFM)insulator to ferromagnetic(FM)metal and a spin transition from S=2 to S=1.We reproduce these transformations in our calculations and give a clear physical interpretation.
基金supported by the National Natural Science Foundation of China(11464045)Autonomous Region Postgraduate Research Innovation Fund Project(XJGRI2016093)+1 种基金the subject of Xinjiang Normal University Key Laboratory(KWFG1605)the Introduction Program of High-Level Talents of Xinjiang Province
文摘A series of tunable phosphors NaAlSiO_4:Ce^(3+),Sm^(3+) were synthesized using a conventional high-temperature, solid-state method. Crystal structure, photoluminescence excitation, and emission spectra with fluorescence decay curves were investigated. Under UV excitation(325 nm), NaAlSiO_4:Ce^(3+),Sm^(3+) showed strong blue emission located at 444 nm and orange-reddish emission centered at 563, 601, 648 and 712 nm, stemming from the characteristic emission for 4f-5d transition of Ce^(3+) and ~4G_(5/2)→~6H_J(J=5/2, 7/2, 9/2, 11/2) transition of Sm^(3+), respectively. In addition, we studied the detailed energy transfer process between Ce^(3+) and Sm^(3+) and found that it belonged to dipole-dipole resonance energy transfer. Furthermore, we noted that the white light emitting from the Ce^(3+), Sm^(3+) co-doped phosphors with the color coordinate(x=0.313, y=0.283) could be observed under 325 nm excitation, which was close to the ideal white light(x=0.33, y=0.33). The results indicated that this phosphor has a potential application as a single-phased alumino-silicate phosphor for ultraviolet white light-emitting diodes(UV-WLEDs).