RESUMO
In this Letter, CeO2: Er³âº, Tm³âº, Yb³âº inverse opal with near-infrared to near-infrared upconversion emission was prepared by polystyrene colloidal crystal templates, and the influence of photonic bandgap on the upconversion emission was investigated. Comparing with the reference sample, suppression of the blue or red upconversion luminescence was observed in the inverse opals. It is interesting that the near-infrared upconversion emission located at about 803 nm was enhanced due to the inhibition of visible upconversion emission in the inverse opals. Additionally, the variety of upconversion emission mechanisms was observed and discussed in the CeO2: Er³âº, Tm³âº, Yb³âº inverse opals.
RESUMO
The Sb2O4:Yb3+, Tm3+ up-conversion luminescence powder with excellent physical, chemical stability and relative low phonon energy was synthesized by the high temperature solid-state reaction and its up-conversion luminescence property was investigated. Under the 980 nm excitation, infrared and blue up-conversion emissions centered at 800 and 480 nm were observed, which were assigned to the 1G4-->3H6 and 3H4-->3 He transitions of Tm2+, respectively. The influence of Yb3+ and Tm3+ concentration on the up-conversion emission property was also obtained. The up-conversion luminescence increases with increasing of Yb3+ and Tm3+ concentration. Additionally, the up-conversion luminescence mechanism was discussed based on the dependence of Tm3+ up-conversion luminescence on pump power. It is interesting that two photon excitation processes for blue and infrared emission were observed in the Sb2O04: Yb3+, Tm3+ powder under a 980 nm excitation. Based on the energy level diagram of Tma3 and Yb2+ ions, we think that two photons blue emission is contributed to the cooperation energy transfer between Tm"+ and Yb3+ ions. We believe that the Sbz04 : Yb3 , Tm2+ up-conversion luminescence powder will have potential application for new optical devices in up-conversion color displays, sensors, detection of infrared radiation, and lasers.
RESUMO
The upconversion emission of rare earth ions can be modified in photonic crystals, however, the influence of upconversion emission modification of rare earths on near infrared emission has not been investigated yet in the photonic crystals. In the paper, CeO2: Er³âº, Yb³âº inverse opals with the photonic band gaps at 545, 680 and 450 nm were prepared by polystyrene colloidal crystal templates. The upconversion and the near infrared emission properties of Er³âº ions were systematically investigated in the CeO2: Er³âº, Yb³âº inverse opals. Comparing with the reference sample, significant suppression of both the green and red upconversion luminescence of Er³âº ions were observed in the inverse opals. It is interesting that the infrared emission located at 1,560 nm was enhanced due to inhibition of upconversion emission in the inverse opals. Additionally, mechanism of upconversion emission of the inverse opal was discussed. The photon avalanche upconversion process is observed.
RESUMO
In this paper, highly ordered crystalline colloidal arrays containing rare earth fluoride microcrystals were fabricated. The upconversion emission property of rare earth fluoride microcrystals in crystalline colloidal arrays was studied and modified. A significant suppression and enhancement of the upconversion emission from the rare earth fluorides can be observed in the regions of the photonic band gap and its band edge, respectively. The suppression or enhancement factor was shown to be related to the ordered degree of the crystalline colloidal arrays and is critical in the preparation of upconversion displays and low-threshold lasers.