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21.
《Current Applied Physics》2015,15(7):761-764
ZnS thin films were deposited on glass substrates by a chemical bath deposition method using a substrate activation process in which aluminum ions become “contaminants” that act as a nucleation center for active components within the deposition solution. The structure and morphology results demonstrate that the films have a ZnS sphalerite crystal structure with a particle size less than 15 nm, and the films consist of small homogeneous grains. The effects of the substrate activation process on the band gap energies and donor-acceptor pair luminescence process were also investigated. A green emission centered at 502 nm was produced due to donor-acceptor transitions from the aluminum acceptor to the ionized and substitution aluminum centers (Al3+). 相似文献
22.
《Current Applied Physics》2015,15(3):248-252
Red phosphors Ca9Bi1-x(PO4)7:xEu3+ (x = 0.06, 0.10, 0.20, 0.30, 0.40, 0.50, 0.60, 0.70, 0.80 and 1.00) were synthesized by a conventional solid-state reaction (SSR) route. The X-ray diffraction patterns, photoluminescence spectra, ultraviolet–visible reflection spectroscopy, decay time and the International Commission on Illumination (CIE) chromaticity coordinates of these compounds were characterized and analyzed. The Eu-doped Ca9Bi(PO4)7 phosphors exhibited strong red luminescence which peaks located at 615 nm due to the 5D0→7F2 electric dipole transition of Eu3+ ions after excitation at 393 nm. Ultraviolet–visible spectra indicated that the band-gap of Ca9Bi0.30(PO4)7:0.70Eu3+ is larger than that of Ca9Bi(PO4)7. The results indicate that the phosphor Ca9Bi0.30(PO4)7:0.70Eu3+ can be a suitable red-emitting phosphor candidate for LEDs. 相似文献
23.
24.
Cu, Mn co-doped ZnO nanoparticles were successfully synthesized by the sol–gel technique. XRD pattern described that Mn-doping did not affect the hexagonal wurtzite structure of the samples and no secondary phases were found. The reduced crystallite size at Mn=2% is due to the suppression of grain surface growth by foreign impurity. The enhancement of crystal size after Mn=2% is due to the expansion of lattice volume produced by the distortion around the dopant ion. The better dielectric constant and conductivity noticed at Mn=2% are explained by charge carrier density and crystallite size. The suppression of broad UV band by Mn-doping is discussed based on the generation of non-radiative recombination centers. Hysteresis loop showed the clear room temperature ferromagnetism in all the samples and the magnetization increased with Mn-doping. Better electrical and magnetic behavior of Zn0.94Cu0.04Mn0.02O sample is suggested for effective opto-magnetic devices. 相似文献
25.
Nanoparticles of ZnS:Fe (0, 1, 3, and 5 at%) were synthesized by a refluxing route at 80 °C. All the samples exhibited cubic structure as revealed by X-ray powder diffraction studies. Blue emission of undoped samples was totally quenched by Fe doping. Magnetic measurements showed that the undoped ZnS was diamagnetic whereas all the doped samples were paramagnetic at room temperature. EPR signal characteristic of Fe3+ was observed in all the doped samples at room temperature. The paramagnetism of the present samples is attributed to the presence of uncoupled Fe3+ ions mediated by cation vacancies. 相似文献
26.
The effect of Fe-doping on the structural, morphological and optical properties of ZnO nanoparticles synthesized by simple solution combustion process are reported. The powder XRD pattern indicates that the Fe-doped ZnO samples exhibit primary and secondary phases. The primary phase indicates the hexagonal wurtzite structure with the average crystalline size of around 25–50 nm and the secondary phase is associated with the face centered cubic structure of magnetite iron oxide. The elemental composition of pure and Fe-doped samples are evaluvated by EDX. The results of FE-SEM and HR-TEM cleary show that particles morphology have changed with respect to the incorporation of doping agent and particles are in aggregating nature. The vibrational properties of the synthesized ZnO nanoparticles are investigated by Raman scattering technique and it exhibits that the influence of Fe-doping significantly modify the lattice vibrational characteristics in ZnO sites. The optical properties of the Fe-doped ZnO nanoparticles are carried out by UV–vis absorption and PL spectra. The results of PL spectra show the near-band edge related emission as well as strong blue emissions in the Fe-doped ZnO nanoparticles. 相似文献
27.
Structural and optical properties of 1 at % Al-doped Zn1−xMgxO (x=0–8%) powders prepared by sol–gel method were systematically investigated by means of X-ray diffraction, scanning electron microscopy, ultraviolet–visible absorbance measurement, photoluminescence and Raman scattering spectra. All the powders retained the hexagonal wurtzite structure of ZnO. The band gap and near band emission energies determined from absorbance and photoluminescence spectra increased linearly with increasing Mg content, respectively, which implied that the Mg worked effectively on ZnO band gap engineering, irrespective of Al codoping. However, according to the PL and Raman scattering studies, for the sample of x=8%, the Al doping efficiency was decreased by higher Mg codoping. On the other hand, the effect of Mg codoping on photocatalytic degradation of methylene orange was explored experimentally. The substitution of Mg ions at Zn sites shifted the conduction band toward higher energies and then enhanced the photocatalytic activity, while the incorporation of interstitial Mg ions and decreased Al doping efficiency for higher Mg doping sample (x=8%) reduced the photocatalytic activity. 相似文献
28.
Yang Xian-hengFeng Guo-yingYi Jia-yuWang Shu-tongZhou Shou-huan 《光谱学与光谱分析》2015,(9):2483-2486
Thin films of Nd : YAG and Nd : Glass were prepared on Si (100) substrate by pulsed laser deposition technology. The morphology of film surface and cross section, composition, absorption spectrum and photoluminescence (PL) spectra of films were investigated by scanning electron microscope (SEM), energy disperse spectroscopy (EDS), Fourier transform infrared spectrometer(FTIR), optical parametric oscillator(OPO) and grating spectrometer. The results show that both Nd : YAG films and Nd : Glass films grown on the substrates at room temperature are amorphous. Nd : YAG films grown by PLD contain Nd element with 0. 15 at. % stoichiometric proportion. The absorption spectrum of bulk Nd : YAG target rather than deposited films exhibit two absorption peaks at 750 and 808 nm. There are no evident peaks in the photoluminescence spectra curve of Nd : YAG films. However, the photoluminescence spectra of Nd : Glass films with two sharp peaks at the wavelength of 877 and 1 064 nm are observed. It indicates that Nd is doped into glass host as optically active Nd3+ ions when Nd : Glass films grow at room temperature. But for Nd : YAG films, Nd don't incorporate into YAG host as Nd3+ ions. 相似文献
29.
《Current Applied Physics》2019,19(11):1177-1181
We investigated the visible emission property of SrTiO3 (STO) single crystals with high temperature annealing in some ambient conditions. We found that the green emission in STO, which should be associated with intermediate states originating from functional ionic defects inside the samples, such as cation/oxygen vacancies, showed strong ambient dependence. While high temperature annealing in the O2 atmosphere suppressed the intensity of visible emission, annealing in an O2-free atmosphere, such as N2 or H2, increased it. The broad visible emissions were fitted with three sub-modes, whose intensities showed different evolutions with respect to the ambient condition. Our study demonstrated the systematic development of defect states with the amount of the oxygen vacancies in STO. 相似文献
30.
Abstract . The solvothermal reaction between cuprous iodide and the rigid triangular imidazole ligand in mixed N,N′‐dimethylacetamide (DMA)‐acetonitrile solvent leads to the isolation of the 3D metal‐organic framework [(Cu4I4)3(TIPA)4] · 7DMA ( 1 ) [TIPA = tri(4‐imidazolylphenyl) amine], which was characterized by elemental analysis, IR spectroscopy, powder X‐ray diffraction, and single‐crystal X‐ray diffraction. Topologically, the structure of 1 is an unprecedented 3,3,4,4‐connected net with a point symbol of {4.8.10}2{4.82}2{42.82.102}2{84.122}. Compound 1 exhibits orange‐red photoluminescence with an emission maximum at 622 nm at room temperature. 相似文献