Shu Fen Wang

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.

Luminescent characteristics of Eu3+ in SnO2 nanoparticles

Abstract Nanometer-scale SnO2 particles have been synthesized by a simple coprecipitation method. X-ray diffraction analysis shows that the diameter of the particles is 2.6 nm after heat treatment at 400 °C for 2 h. The UV–visible absorptive spectra and photoluminescence spectra have been used to study the luminescence character of Eu3+ ions. The characteristic emission and concentration quenching of Eu3+ ions can be observed. The results also reveal that the Eu3+ ions can be situated not only at the surface of the SnO2 nanoparticles but also in the host lattice, though the relative quantity is very small.

Luminescent properties of Mn2+-doped SnO2 nanoparticles

Abstract The room temperature photoluminescent properties of manganese-doped tin oxide nanoparticles are reported. The samples are crystalline with a tetragonal rutile structure of tin oxide. The FTIR and the UV–Vis absorptive spectra of the samples have also been investigated. The photoluminescence spectra are measured at room temperature as a function of different calcining temperatures and the Mn2+ concentration, respectively. The luminescence processes are associated with oxygen vacancies in the host and related with the recombination of electrons in singly occupied oxygen vacancies with photoexcited holes in the valence band.

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.

Effect of Al3+ on the photoluminescence properties of Ni2+-doped sol–gel SiO2 glass

Abstract Ni2+-doped SiO2, Al2O3–99SiO2 glasses have been prepared by sol–gel method. The effect of Al3+ on the photoluminescence (PL) properties of Ni2+-doped SiO2 has been studied. Ni2+-doped sol–gel SiO2 glass shows an emission band at 510 nm, which is attributed to the d–d transition 1 T 2 ( 1 D )→ 3 A 2 ( 3 F ) of Ni2+ in octahedral sites. The emission of Ni2+ ions is greatly enhanced by the addition of Al3+ into SiO2. The study on Fourier transform infrared spectroscopy (FT-IR) and UV–Vis absorption spectra shows that the glass network and coordination environment of Ni2+ are changed after adding Al3+ into SiO2.

Effect of Pb2+ on the photoluminescence characteristics of ZrO2: Mn2+ nanocrystals

Abstract The photoluminescence (PL) properties of the Mn, Pb co-doped ZrO 2 nanocrystals have been investigated in detail. A relatively broad and strong emission band centered at about 640 nm was observed originating from the 4 T 1 ( 4 G) to the 6 A 1 ( 6 S) transition of Mn 2+ . In the presence of Pb 2+ , the luminescent intensities of the ZrO 2 : Mn nanocrystals have been greatly enhanced due to the energy transfer from Pb 2+ to Mn 2+ . As a concentration quenching exists, the optimum value of Pb 2+ is 5%.