Metal nanoparticle plasmons or the photonic crystal effect are being widely used to modify luminescence properties of materials. However, coupling of surface plasmons with photonic crystals are seldom reported for enhancing luminescence of materials. In this paper, a new method for upconversion emission enhancement of rare-earth doped nanoparticles is reported, attributed to the coupling of surface plasmons with photonic band gap effects. Opal/Ag hybrid substrates were prepared by depositing Ag nanoparticles on the top layer of opals by magnetron sputtering. The selective enhancement of red or green upconversion emission of NaYF4:Yb3+,Er3+ nanoparticles on the opal/Ag hybrid substrates is attributed to the coupling effect of surface plasmons and Bragg reflection of the photonic band gap. In addition, the upconversion emission enhancement of NaYF4:Yb3+,Er3+ nanoparticles on the opal/Ag hybrid substrate is attributed to the excitation enhancement was obtained when the excitation light wavelengths overlap with the photonic band gaps of opal/Ag hybrid substrates. We believe that these enhancement effects based on the coupling of metal nanoparticles with the photonic band gap could be extended to other light-emitting materials, which may result in a new generation of lighting devices.

The existing states of silver depend on the sintering temperature of SiO 2 three-dimensionally ordered macroporous (3DOM) materials. Several species related to silver (Ag + ions, Ag + -Ag + and Ag nanoparticles) were demonstrated in SiO 2 3DOM materials prepared at 550 1C. Only Ag nanoparticles were observed in SiO 2 3DOM materials prepared at 750 1C. The influence of silver species on the photoluminescence properties of Eu 3+ was investigated systematically in SiO 2 3DOM materials. The results show that photoluminescence enhancement of Eu 3+ ions was induced by Ag species in SiO 2 3DOM materials. For the SiO 2 3DOM materials prepared at 550 1C, the enhancement of Eu 3+ luminescence is attributed to energy transfer from Ag + -Ag + to Eu 3+ under excitation at 345 or 280 nm, while the luminescence enhancement of Eu 3+ is due to energy transfer from isolated Ag + to Eu 3+ under excitation at 245 nm. For the SiO 2 3DOM materials prepared at 750 1C, the luminescence of Eu 3+ was enhanced due to the plasmon resonance effect of Ag nanoparticles.

The photoluminescence properties of silver species, including Ag + , Ag + -Ag + , Ag 0 , and Ag nanoparticles in various matrices, such as gel and glass have been extensively reported. In the present study, we present the preparation of silver including SiO 2 three-dimensionally ordered macroporous (3DOM) materials and investigate the existing states and photoluminescence property of silver in the SiO 2 3DOM materials. The results show that only Ag + ions exist in the SiO 2 3DOM materials sintered at temperature below 400 C. With the increasing sintering temperature, the Ag + ions gradually transform into Ag + -Ag + , where simultaneously, a part of Ag + -Ag + transform into Ag nanoparticles. The Ag + -Ag + and Ag nanoparticles are formed in the SiO 2 3DOM materials sintered at temperature from 450 to 650 C. Finally, only Ag nanoparticles occur in the SiO 2 3DOM materials prepared at 750 C. The formation mechanisms of Ag species were discussed in the SiO 2 3DOM materials.

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