Chun Feng Song

Synthesis and luminescence properties of SnO2 nanoparticles

Abstract Nanometer-scale SnO 2 particles have been synthesized by a simple sol–gel method. The samples were characterized by X-ray diffraction, Fourier transform infrared (FTIR), UV–Vis absorption and photoluminescence spectroscopy. The as-prepared SnO 2 nanoparticles appear to be single tetragonal crystalline phase and the diameter is about 2.6 nm. The origin of luminescence is assigned to the recombination of electrons in singly occupied oxygen vacancies with photoexcited holes in the valence band.

The luminescence of PbS nanoparticles embedded in sol–gel silica glass

Abstract PbS nanoparticles embedded in a novel silica glass have been achieved in the present study by sol–gel processing. Their fluorescence properties have been evaluated and compared with those of un-doped glass. A novel luminescent phenomenon has been observed from the composite of PbS nanoparticles and the sol–gel silica glass. The photoluminescence (PL) spectrum of the composite consists of two emission peaks (440 and 605 nm). The Pb 2+ ions in the sol–gel silica glass show sharp emission band. This novel luminescence from the samples is assigned to the composite structure of PbS nanoparticles and porous silica glasses.

Structure and photoluminescence properties of sol–gel TiO2–SiO2 films

TiO2–SiO2 films (Ti/Si=1:1) have been prepared by the sol–gel method. The structure and photoluminescence (PL) properties of the films heat-treated at different temperatures have been investigated. The films appear composed of TiO2 nanocrystallites in anatase form embedded in SiO2-rich matrix. Emission bands are observed in all the heat-treated films. This PL is attributed to various defects resulting from thermal treatment and crystallization of TiO2 and to energy levels in the mixed oxide matrix.

Photoluminescence characteristics of Pb2+ ion in sol–gel derived ZnTiO3 nanocrystals

Abstract Pb 2+ ions doped ZnTiO 3 nanocrystal has been prepared by a sol–gel process. The X-ray diffraction patterns indicate that the doped sample exhibits a cubic ZnTiO 3 structure. From the luminescence spectra analysis, the introduction of Pb 2+ ions into ZnTiO 3 results in novel luminescent properties. A red emission band fixed at 620 nm has been observed. The relative intensities of the bands vary with the concentration of Pb 2+ ions. The luminescence due to Pb 2+ -involved centers can be ascribed to the Pb 2+ -related charge-transfer transition in ZnTiO 3 nanocrystals.

Photoluminescence of sol–gel derived ZnTiO3:Ni2+ nanocrystals

Cubic ZnTiO3 nanocrystal doped with Ni2+ ion has been synthesized by sol–gel method at a lower temperature (600 °C). The crystallinity of the doped sample was characterized by the X-ray diffraction (XRD) patterns and the infrared spectra (IR). The photoluminescence (PL) spectra of the sample measured at different excitation wavelength reveal a novel luminescent phenomenon in blue, green and red region, which can be attributed to the 3T1(3P)–3A2(3F), 1T2(1D)–3A2(3F) and 1T2(1D)–3T2(3F) transitions of Ni2+ ion, respectively. The position of the emission peak does not change greatly with the excitation wavelength. However, the luminescent intensities vary with changing the concentration of Ni2+ ion in ZnTiO3.

Preparation and characterization of sol-gel derived ZnTiO3 nanocrystals

Nanometer scale cubic ZnTiO{sub 3} has been synthesized by sol-gel method at a lower temperature (600 deg. C). X-ray diffraction (XRD) analysis shows that the average crystalline size of the sample is {approx}8-10 nm. The cubic to hexagonal phase transition of ZnTiO{sub 3} is clearly observed from the XRD patterns of the sample. The thermal behavior of the sample was characterized by the thermogravimetric/differenthermal analysis (TG/DTA), XRD patterns, and the infrared spectra (IR). Transmission electron microscope (TEM) observations of the sample reveal a high microstructural uniformity.

Luminescence of Cu2+ and In3+ co-activated ZnS nanoparticles

Abstract Zinc sulfide (ZnS) nanoparticles co-doped with Cu2+ and In3+ ions have been prepared by precipitation from homogeneous solutions of zinc, copper and indium salt compounds, with S2− as precipitating anion formed by decomposition of thioacetamide. The estimated average crystallite size of doped and undoped ZnS nanometer scale samples is about 2–3 nm from X-ray diffraction patterns. Novel luminescence characteristics (green emission, λem∼530–550 nm) have been observed from the co-doped ZnS nanocrystals at room temperature. The emission wavelength and relative photoluminescense intensity of the co-doped samples vary with changing the impurity ratios of Cu2+ and In3+.

A potential blue photoluminescence material: ZrO2-SiO2 glasses

nZrO2–(100−n)SiO2 (n=0.5, 1, 2, and 3 wt.%) glasses have been prepared by sol–gel method. Photoluminescence (PL) properties of the samples heated to various temperatures were investigated for the first time. Strong blue emission band centered at 442 nm was observed from sol–gel ZrO2–SiO2 glasses. The blue emission is assigned to defects in the ZrO2–SiO2 network. The heat treatment has a large effect on the PL intensity of the ZrO2–SiO2 samples. The PL intensity is also changed with different ZrO2 content.

Preparation and tunable photoluminescence characteristics of Ni2+:SrAl2O4

Abstract Samples of SrAl 2 O 4 and Ni 2+ :SrAl 2 O 4 were prepared by solid states reactions. Microstructures of the samples were analyzed by X-ray diffraction (XRD). The XRD patterns of the undoped sample calcined at 1100 °C reveal that it exhibits a single SrAl 2 O 4 crystalline phase. No characteristic peaks of dopant have been observed in XRD patterns of the doped sample. The tunable photoluminescence (PL) has been observed from the SrAl 2 O 4 sample doped with Ni 2+ ions. The PL spectra of the doped sample are strongly dependent on the excitation energy. The tunable luminescence of the doped sample originates from d–d optical transitions of Ni 2+ (d 8 ) ions in SrAl 2 O 4 .

Photoluminescence of Bi3+ ions in sol–gel derived Zn2SiO4

Abstract The luminescence of sol–gel derived Zn 2 SiO 4 powder sample doped with Bi 3+ ions has been presented in this paper. From the photoluminescence (PL) spectra of the doped sample, it can be concluded that Bi 3+ -doped Zn 2 SiO 4 powder is an interesting PL material whose luminescence properties are adjusted by changing the excitation wavelength. The luminescence of Bi 3+ ions is quite diverse in Zn 2 SiO 4 powder sample. The blue and yellow emission bands have been observed from the doped Zn 2 SiO 4 powder. This novel luminescence property is attributed to an energy transfer involving Bi 3+ , Zn 2+ , and Si 4+ ligand of Zn 2 SiO 4 lattice.