Su Wen Liu

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.

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.

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.

Preparation and characteristics of sol–gel derived Zn2SiO4 doped with Ni2+

Abstract The changing presented during the heating of sol–gel derived Zn2SiO4 doped with Ni2+ have been investigated by X-ray diffraction (XRD) and differential thermal analysis (DTA). When calcining temperature 900 °C, XRD pattern of the sample shows the characteristic peaks of α-Zn2SiO4 crystal phase. Also, the excitation and emission spectra of the undoped and Ni2+-doped samples have been investigated. Stable green–yellow–red emission has been observed from Zn2SiO4 crystalline phase. A novel photoluminescence (PL) phenomenon has been observed from Ni2+-doped Zn2SiO4.

Photoluminescence characteristics and mechanism of SrAl2O4 co-doped with Eu3+ and Cu2+

Abstract SrAl 2 O 4 co-doped with Cu 2+ and Eu 3+ was prepared at high temperature in a weakly oxidizing atmosphere by solid states reaction. X-ray diffraction (XRD) pattern of the sample shows that the doped sample exhibits SrAl 2 O 4 crystalline phase. No characteristic peaks of dopant have been observed in XRD pattern of doped sample. The excitation and emission spectra of CuEu:SrAl 2 O 4 , Eu:SrAl 2 O 4 , Cu:SrAl 2 O 4 samples consist of many sharp peaks. The excitation and emission spectra of the SrAl 2 O 4 sample co-doped with Cu 2+ and Eu 3+ are significantly different from those of Eu:SrAl 2 O 4 and Cu:SrAl 2 O 4 samples. The novel photoluminescence (PL) characteristic of the co-doped sample is attributed to the composite luminescence of Cu 2+ and Eu 3+ ions in SrAl 2 O 4 matrix.

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%.