Mashadi .; Wisnu Ari Adi; Yunasfi .
Abstract
Effect of Nd-concentration in Nd(2-x)FexO3 system on the structure and microwave absorption characteristics have been studied. Nd(2-x)FexO3 system is one of perovskite based system which has a relative high permittivity. Nd(2-x)FexO3 (x=0.5; 1.0 and 1.2) samples were synthesized by Fe(NO3)3 and ...
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Effect of Nd-concentration in Nd(2-x)FexO3 system on the structure and microwave absorption characteristics have been studied. Nd(2-x)FexO3 system is one of perovskite based system which has a relative high permittivity. Nd(2-x)FexO3 (x=0.5; 1.0 and 1.2) samples were synthesized by Fe(NO3)3 and Nd(NO3)3 in mole ratio using sol–gel method and then sintered at 800°C for 5 hours. All of the samples were characterized using XRD to identify the phase, SEM to observe the morphology and VNA was used to measure the microwave absorption. Phase identification of XRD data shows that single phase of NdFeO3 have been formed for x = 1.0 composition (ABO3). While multiphase have been formed which is indicated by the appearance of NdFeO3 and Nd2O3 phase for x = 0.5, and then NdFeO3 and Fe2O3 phase for x = 1.2. SEM image shows the samples of Nd(2-x)FexO3 have homogenous morphology with particle size is approximately 200 nm. The results of microwave absorbing properties measured by using VNA (Vector Network Analyzer) shows the best ability of microwave absorption is x = 1.0 composition is around 96.27% at frequency of 10.46 GHz.
N. Manjula; S. Ramu; K. Sunil Kumar; R. P. Vijayalakshmi
Abstract
Pristine BiFeO3 (BFO) and Ca doped BiFeO3: Ba nanoparticles (NPs) were synthesized in aqueous solution by sol-gel method with Tartaric Acid as a chelating agent. EDAX measurements confirmed the presence of Ca, Ba in the BiFeO3 host lattice. X-ray diffraction analysis showed that the average grain size ...
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Pristine BiFeO3 (BFO) and Ca doped BiFeO3: Ba nanoparticles (NPs) were synthesized in aqueous solution by sol-gel method with Tartaric Acid as a chelating agent. EDAX measurements confirmed the presence of Ca, Ba in the BiFeO3 host lattice. X-ray diffraction analysis showed that the average grain size of the prepared samples was in the range of 09–28 nm. The lattice structure of the nanoparticles transformed from rhombohedral to tetragonal phase with Ca 2+ ions substitution increased. TEM images indicated that sphere and square shape of nanoparticles through a size ranging from 10 to 15 nm. Diffusion reflectance spectra of BiFeO3 NPs showed a substantial blue shift of ~100 nm (630 nm -> 530 nm) on Ca, Ba co-doping which corresponds to increase in band gap by 0.47 eV. Dielectric constant (ε’) and dielectric loss (ε’’) were measured in the frequency range 1 Hz to 1 MHz at room temperature. Dielectric constant and loss are increased with Ca concentration except for Ca (4 at. %). The bulk conductivity (σ) increases from 3.07 x 10 -6 S/m to 1.64 x 10 -5 S/m as the Ca concentration increased from 0.00 to 0.03. Magnetic measurements revealed the ferromagnetic character of Pristine BFO and Ca doped BiFeO3: Ba samples. It is observed that by increasing the Ca concentration the value of Mr and magnetization are varied irregularly upto Ca (4 at. %). But for x = 0.01 Mr and magnetization are highest. The values of magnetization and Mr for 1% Ca doped BiFeO3: Ba NPs are 2.99 emu/g, 1.54 emu/g, respectively, which are quite significant at room temperature. These materials have potential applications in data storage, switching devices, spintronics, sensors and microelectronic.
Amel Tounsi; Djahida Talantikite-Touati; Hamid Merzouk; Hadjira Haddad; Roumaïssa Khalfi
Abstract
The thin layers of undoped ZnS and ZnS doped La with different concentrations (2, 4, 6, 8 and 10%) were deposited on glass substrates using sol-gel and dip-coating methods. The structural characterization of these samples was carried out by the X-rays diffraction (XRD), scanning electron microscopy ...
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The thin layers of undoped ZnS and ZnS doped La with different concentrations (2, 4, 6, 8 and 10%) were deposited on glass substrates using sol-gel and dip-coating methods. The structural characterization of these samples was carried out by the X-rays diffraction (XRD), scanning electron microscopy (SEM) and atomic force microscopy (AFM). UV-visible and Fourier Transform Infrared spectroscopy (FTIR) have been used to study the effect of dopant on the optical properties of ZnS doped La thin films. Atomic force microscopy images of the films have revealed homogeneous and granular structure and the SEM micrographies show deposit films with uniform and porous structure. The optical transmission spectra in the UV - visible range have shown that all the doped films present a good optical transmission in the visible domain.
Abstract
Zinc oxide (ZnO) nanoparticles (NPs) were synthesized by different methods known as Pechini and Sol-Gel. It was observed during the experiments significant differences comparing these methods as: particle size, time applied, crystallinity and chemical residues generated by-products. The NPs were analysed ...
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Zinc oxide (ZnO) nanoparticles (NPs) were synthesized by different methods known as Pechini and Sol-Gel. It was observed during the experiments significant differences comparing these methods as: particle size, time applied, crystallinity and chemical residues generated by-products. The NPs were analysed by X-ray diffraction (XRD), ultraviolet-visible (UV-Vis.) absorption and Raman spectroscopy techniques. X-Ray Difractograms showed peaks corresponding to hexagonal wurtzite crystalline structure. It was observed that NPs obtained by the Pechini showed better homogeneity and crystallinity; these presented average size of 115 nm. The NPs produced by Sol-Gel method showed crystallites with smaller average size of 8 nm. The band gap energy (Eg) obtained using UV-Vis for ZnO NPs synthesized by Pechini was 3.39 eV. Still, the results for Sol-Gel method with 5 and 10 hours of reactions were 3.53 eV and 3.55 eV respectively. Raman data obtained by Pechini and Sol-Gel Methods showed characteristics peaks. The obtained data confirmed the ZnO phase samples and the proportional relationship to the enlargement with the intensity of peaks E2 High ˜ 438 cm -1 , as evidenced by literature. These results lead to the applicability of both NPs in optoelectronic and fluorescent applications.
Mpho W. Maswanganye; Koena E. Rammutla; Thuto E. Mosuang; Bonex W. Mwakikunga; Sone T. Bertrand; Malik Maaza
Abstract
Co and In co-doped nanopowders of ZnO as well as In and Co singly doped ZnO were successfully prepared using sol-gel method. The synthesized samples were characterized using x-ray diffraction (XRD), UV-vis spectroscopy (UV-vis), Raman spectroscopy (RS), Transmission Electron Microscopy (TEM) and Energy ...
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Co and In co-doped nanopowders of ZnO as well as In and Co singly doped ZnO were successfully prepared using sol-gel method. The synthesized samples were characterized using x-ray diffraction (XRD), UV-vis spectroscopy (UV-vis), Raman spectroscopy (RS), Transmission Electron Microscopy (TEM) and Energy Dispersive Spectroscopy (EDS). The effects of In and Co co-doping on the structural and optical properties were investigated. XRD results showed no peaks associated with In 3+ or Co 2+ ions indicating that In 3+ and Co 2+ ions substituted for Zn 2+ ions in the ZnO wurtzite structure, this was corroborated by the EDS results. Doping ZnO nanoparticles with In and Co significantly reduced the grain sizes whereas the lattice parameters were not significantly affected. TEM results confirmed that the nanoparticles were spherically shaped. Raman spectroscopy also confirmed that the ZnO nanoparticles were of a wurtzite hexagonal structure. Single doping reduced the energy band gaps and co-doping reduced them even further.
Deman Han; Yongmin Li; Wenping Jia
Abstract
A novel 2, 4-dichlorophenol imprinted TiO2-SiO2 catalyst was prepared by molecular imprinting technique in combination with sol-gel method. The prepared material was characterized by X-ray diffraction (XRD), infrared spectroscopy (IR), scanning electron-microscopy (SEM), transmission electron microscopy ...
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A novel 2, 4-dichlorophenol imprinted TiO2-SiO2 catalyst was prepared by molecular imprinting technique in combination with sol-gel method. The prepared material was characterized by X-ray diffraction (XRD), infrared spectroscopy (IR), scanning electron-microscopy (SEM), transmission electron microscopy (TEM) and N2 adsorption measurement. The effect of the preparation condition on the degradation behavior, the photo-catalytic ability and selectivity of the prepared material were evaluated. The results show that the imprinted material has good photo-degradation capacity and selectivity toward the target pollutant, which was shown to be promising for selective removal of 2, 4-dichlorophenol from environmental samples.
Li Chen; Guangshui Yua;Jianming Zhanga; Xiujiang Pangb
Abstract
Multi-walled carbon nanotubes (MWNTs) were in-situ coated with anatase TiO2 via sol-gel process followed by annealing of the composites using infrared (IR) lamp. SEM results showed that MWNTs were coated with 15-45 nm thick TiO2 layer depending on the composite ratios. Based on the XRD results, MWNTs ...
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Multi-walled carbon nanotubes (MWNTs) were in-situ coated with anatase TiO2 via sol-gel process followed by annealing of the composites using infrared (IR) lamp. SEM results showed that MWNTs were coated with 15-45 nm thick TiO2 layer depending on the composite ratios. Based on the XRD results, MWNTs were found to show heterogeneous nucleation for anatase TiO2 and promote the formation of larger anatase TiO2 crystalline particles with higher crystalline degree. The UV-Vis- NIR characterization indicated the MWNTs also enhanced the sensitivity of TiO2 matrix for both UV and visible light, and the bond edge absorption position of the TiO2 composites shifted toward higher wavelengths with the decrease of MWNTs content. The method could be utilized to fabricate MWNTs /TiO2 composites conveniently.
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