Preparation Of Nanoscale Cluster-based Composite Materials And Their Spectroscopic Characteristics

Since the ninetieth decade last century, efforts have been made to develop rare earth (RE) doped non-oxide glasses into light amplifying materials. Rare earth ions doped halides and mixed halides with higher quantum efficiencies had also been discovered. Nevertheless, there had been concerns that these halide and mixed halide light amplifying materials were fragile, sensitive to moisture, and not suitable for being welded with the widely used quartz fibers. These intrinsic drawbacks have prevented the RE doped non-oxide glasses from engineering applications as optical amplifying materials and luminescent materials. In this paper we took advantage of nanoporous silica glass to develop the optical composite material that was nanoscale fluoride glass granules embedded in silica glass. The network of the non-oxides glass is interwoven with the network of silica glass. This material combines the advantage of non-oxides glass as a good optical amplifying substrate with that of silica glass as a good protector and holder. In addition, a gradient concentration of the non-oxides in silica glass along one dimension may allow for almost pure silica glass at two ends of the material, which would lead in turn to the welding ability of the material with quartz fibers.The nanoporous glass was prepared using an improved method of phase separation and acid eroding of sodium borosilicate glass. The spacing between the skeletons and the thickness of the skeleton are both 20-30nm in average. The melt of Er3+/Yb3+ doped fluoride glass was irrigated into the porous glass to make a new composite material. Up-conversion spectrum of the composite material was observed, which was different from that of the bulk Er3+/Yb3+ doped fluoride glass. Some related mechanism was also put forwarded. Success of the impregnation process was based on the elimination of water and hydroxyl and the control of etching.Luminescent properties of YOCl:Eu3+ powders and EuCls solution embedded in nanoporous glass were also investigated. In comparison with those in the normal micro-powder phosphor, emission spectra of Eu3+ in nano-YOCl:Eu3+ became much broader. Blueshift(7nm) was observed in the lines due to 5D0→ 7F2 transition and Eu-O charge transfer excitation band. The ratio intensities of the 5D0→ 7F1 transition to the 5D0→7F2 transition of Eu3+ became larger and changed at different excitation wavelengths(254nm and 393nm). In comparison with those in the bulk EuCl3 solution, nano- EuCl3 solution had neither small size effects nor quantum confinement effects. Luminescence due to upper levels of Eu3+ in the nano-solution was enhanced. This approach also combines the advantages of nanoporous glass in offering good chemical shielding and mechanical support. The results obtained indicate that this approach likely may make a new kind of luminescent material.