Xinqiang Yuan

Intense photoluminescence at 2.7 μm in transparent Er 3+ :CaF 2 -fluorophosphate glass microcomposite

Er3+ doped CaF2-fluorophosphate (FP) glass microcomposites were produced by heat-treating the mixture of Er3+:CaF2 precipitate and FP glass powder above the melting temperature of the FP glass. The appearance of CaF2 crystallites in the resulting composites was confirmed by x ray diffraction. Despite the fact that the average diameter of the crystallites was around 10 μm as revealed by the micromorphology study, a transparent composite was obtained by matching the refractive index of FP glass to that of CaF2. Intense IR fluorescence at around 2.7 μm was observed in the composite, implying the composite would be a promising candidate for IR lasers and amplifiers.

Synthesis, characterization and photoluminescence of aluminium nitride nanopowders through an AlCl3 aided CVD route .

Single-phase AlN nanopowders, with average diameter of about 70 nm, were synthesized through an AlCl3 aided CVD route; the formation process is also discussed in this paper. XRD and HRTEM revealed that the AlN nanopowders obtained are wurtzite structured with lattice constants of a = 3.1114 A and c = 4.9792 A. The photoluminescence spectrum showed that there is a deep-level blue luminescence band centred at 2.54 eV in AlN nanocrystals. This method is a simple and efficient way to synthesize AlN nanopowders.

The effect of La2O3 in Tm3+-doped germanate-tellurite glasses for ~2 μm emission

A germanate-tellurite glass (GeO2-TeO2-K2O-Nb2O5-La2O3) with thulium doping has been investigated for application as a laser material around 2.0 μm regions. Under the 808 nm laser diode pumped, intense 1.8 μm emission is obtained. Based on the absorption spectra, radiative properties are predicted using Judd-Ofelt theory. The maximum value of emission cross-section of Tm3+ around 1.8 μm can reach 1.46 × 10−20 cm2, which indicated that the germanate-tellurite glass may provide high gain as a good medium for efficient 1.8 μm laser system.

Two-photon absorption and emission in CsPb(Br/I)3 cesium lead halide perovskite quantum dots

We present the nonlinear optical properties of CsPb(Br/I)3 perovskite quantum dots (QDs) with high crystallinity. The perovskite QDs show better two-photon absorption response than the traditional metal chalcogenide QDs. And, the photoluminescence peak of the halogen vacancies in perovskite nanocrystals was experimentally observed for the first time.

Synthesis of Yb:Lu3Al5O12 nano powders with the reverse strike co-precipitation method: influence of decomposition of NH4HCO3

Abstract Yb:Lu 3 Al 5 O 12 (Yb:LuAG) nano powders were synthesized with the co-precipitation method from cation (Lu 3+ , Yb 3+ , Al 3+ ) solution of different concentrations using NH 4 HCO 3 as the precipitant. The influence of cation concentration on the morphology and purity of the calcined powders was studied. Contrary to the conventional suggestion that recommends thin solution to obtain loosely agglomerated nano powders, results showed that thin cation (Lu+Yb+Al) concentration ≤0.08 mol/L led to formation of Al 2 O 3 and LuAP impurities in the obtained nano powders. By means of Tg/(DTA), X-ray diffraction (XRD), scanning electron microscopy (SEM), the cause was revealed to be re-dissolution of Lu at high pH value that resulted from the decomposition of NH 4 HCO 3 . (Lu+Yb+Al) concentration of ∼0.24 mol/L was recommended to achieve pure Yb:LuAG nano powders. Transparent Yb:LuAG ceramics were fabricated with the prepared Yb:LuAG nano powders. The transmittance around 800 nm was 77.5%.

Tunable and white light emitting AlPO4 mesoporous glass by design of inorganic/organic luminescent species

The realization of tunable and white light emitting sources employed by UV-LED with single-host phosphors has been an exciting development in the search for high luminous efficiency and excellent color rendering index white-light source. A tunable and white light emitting mesoporous glass was prepared by utilizing both inorganic/organic (Europium/coumarin) luminescent species in the meso-structure. The tunable and white light emission was deliberately designed by CIE calculation based on the individual emission spectra, which was realized by tailoring the emission of Eu2+/Eu3+ ions and coumarin 535 in sol-gel AlPO4 mesoporous glass. This simple and versatile procedure is not limited in the combination of rare earth and organic dye and is therefore extendable to other luminescent species in meso-structure for color-tunable efficient solid-state lighting sources.

Tunable and bimodal near-infrared luminescence in nanocrystal-in-AlPO 4 mesoporous glass composites

A new candidate as tailorable luminescent material in near infrared is achieved by designing different composited strategies on PbS quantum dots (QDs) incorporated mesoporous AlPO4 glass. Transmission electron microscopy images and X-ray photoelectron spectroscopy spectra reveal that PbS QDs were embedded in AlPO4 successfully. Photoluminescence spectra characterize a typical emission in near infrared region with a broadband of 242 nm and a bimodal photoluminescence at 970 and 1224 nm, which obtained by two processing strategies. Furthermore, as a result of selective adsorption by size controlled pores of AlPO4 glass, an adjustable fluorescence from 955 to 1061 nm is realized.