Barium zirconium titanate (Ba(ZrxTi1?x)O3, BZT) super smooth thin films are synthesized through modified sol-gel dip coating route on fluorine-doped tin oxide substrates with a suitably low calcination temperature. The Fourier tranformed infrared spectroscopy proves that impurities and starting materials are completely removed in the calcination process. Crystallographic phases of the samples are identified by the X-ray diffractometry and confirms that all samples are crystallized into a single perovskite phase. Introducing zirconium into the structure causes a reduction in dielectric constant of barium titanate. The optical properties of the films are also investigated. The results indicate that all samples are highly transparent and zirconium reduces the absorption coefficient. Moreover, the band gap energy of barium titanate increases when doped with zirconium and the highest band gap energy of about 3.71?eV along with the lowest dielectric constant of 850 at frequency of 100?kHz are obtained in 15 at.% zirconium-doped sample.
Iron and cobalt doped zinc oxide were prepared by the sol–gel method. The doping concentration was varied between 5 and 10?wt.%. Structural and morphological features of the samples were investigated comparatively by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and Fourier transform infrared spectroscopy (FTIR). They were also placed in an electric circuit and their sensing characteristics toward ethanol vapors were studied. It was found that, the gas response was impressed by doping. The optimal operating temperature, dynamic response, sensitivity and response and recovery times of the samples have been measured. The operating temperature and the time of response and recovery of the sensor were generally reduced after doping. According to our results, by considering the time of rising/ falling, the doped samples have a relatively better status than pure zinc oxide sample and in particular, the sample with 10% cobalt doped (ZC10) had a competitive attitude compared to pure zinc oxide due to significant reduction in response/recovery times.
Boron Nitride (BN) particles were functionalized with vinyl-trimethoxysilane (VTMS) and incorporated into a hybrid polymer (ORMOCER®) resin. The thermal conductivity and mechanical properties of the resulting composite were compared to materials prepared using unmodified particles. Results indicate that the chemical bonding between grain surface and ORMOCER® matrix has a pronounced effect on the final performance of the respective compounds.
The surface of BN particles was functionalized prior to their incorporation into a hybrid polymer (ORMOCER®) matrix, thermal, electrical and mechanical properties of the resulting composites were characterized.
Undoped and transition metal (TM: Ni, Mn, Co)-doped CeO2–SnO2 nanocomposite thin films were prepared by sol-gel dip coating (SGDC) technique. The grazing incidence X-ray diffraction (GIXRD) patterns indicated that CeO2–SnO2 film has a cubic structure of CeO2 and the crystallinity deteriorated with incorporation of dopant. The scanning electron microscopy (SEM) and atomic force microscopy (AFM) images showed that the surface morphology of the films was affected by TM incorporation. The surface roughness and fractal dimensions of CeO2–SnO2 films increased with doping. The average transmittance of CeO2–SnO2 thin film is found nearly 80% in the visible region and increased with doping. The absorption edge revealed a blue shift toward shorter wavelengths after incorporation of TM ions. The compositional dependence of optical parameters such as refractive index, extinction coefficient, and optical conductivity were also investigated. Cyclic voltammetry measurements showed that ion storage capacity was decreased significantly with increasing scan rate. The undoped and doped CeO2–SnO2 films showed good reversible cycle of intercalation/deintercalation of Li+ ions. The ion storage capacity and electrochemical stability were enhanced with transition metal doping. The Mn-doped CeO2–SnO2 composite thin film had better ion storage capacity rather than other samples due to its special porous morphology. The Li diffusion toward electrode surface was described in terms of self-similar fractal dimension. A quenching in blue-green photoluminescence (PL) intensity of CeO2–SnO2 films was occurred by transition metal doping.
Nanocomposites of reduced graphene oxide (rGO) coupled gadolinium doped ZnFe2O4 (GZFG) have been successfully one pot in-situ synthesized adopting low temperature solution process from zinc nitrate, iron nitrate, gadolinium acetate and graphene oxide with varying concentrations of gadolinium (upto 10% Gd with respect to Zn) in the precursor medium. X-ray diffraction and transmission electron microscopy studies confirm the presence of single phase cubic spinel structure of ZnFe2O4 that uniformly distributed over the rGO layers. With increasing Gd doping concentration in precursor medium, the average crystallite size of ZnFe2O4 diminishes gradually from ~11 to ~5.5?nm. Raman and X-ray photoelectron spectral analyses confirm an existence of interaction between rGO and ZnFe2O4 in GZFG samples. Using antibiotic levofloxacin in water, the drug removal capacity (DRC) of GZFG has been performed by optimization of parameters such as gadolinium doping concentration in precursor medium, solution pH, etc. However, the gadolinium doping leads to an improvement in DRC of the nanocomposite and the 5% Gd doped sample shows about 86% DRC at the optimized condition. This simple strategy can be utilized in the synthesis of rGO coupled Gd doped other metal oxide nanocomposites for DRC application.
The behaviour of alginate gel film in response to the tensile load is analysed in this paper. The bubbles of 0.5?mm diameter were embedded in the film by the fluidic method prior to gelation, thus providing uniform voidage over the entire film. Further, the intrinsic porosity of the gel matrix around the voids was varied by removing water through either evaporation under vacuum, or employing lyophilisation. The Poisson’s ratio and the modulus of elasticity were estimated from direct measurements. The viscoelasticity of the gel matrix was characterized from stress-relaxation measurement. The transient response to tensile loading and the evolution of stress contours were studied through numerical simulation in ANSYS. The ultimate strength was studied for the gel films with embedded voids of different sizes. The numerical simulations were validated by experimental measurements.
Two series of TiO2 thin films were prepared based on soluble precursor powders: The first run originated directly from an alcohol-based coating solution whereas for the second batch the aqueous precursor powder sol had previously undergone a hydrothermal treatment. The respective microstructures were characterized by electron microscopy, the phase evolution was monitored by X-ray diffraction. Ellipsometric porosimetry (EP) was employed to reveal changes of porosity and pore size induced by thermal treatment of the films.
Soluble TiO2 precursor powders were hydrothermally treated to yield coating solutions. Films from these sols were compared with those directly obtained by dissolving the precursor powders. Results indicate that crystallization to anatase is induced under hydrothermal conditions and the resulting films mostly maintain their porosity throughout thermal treatment. In contrast to that coatings processed from as-dissolved precursor powders undergo more extensive densification
The aim of this work was an investigation of structural and electrical properties of ZnO/Zn2-xFexTiO4 (x?=?0.7, 1, 1.4) powders. The compounds obtained by sol-gel method are characterized by several techniques: X-ray diffraction (XRD), N2 adsorption–desorption isotherms, scanning and transmission electron microscopy (SEM and TEM), X-ray photoelectron spectroscopy (XPS), electrical and dielectrical measurements. The XRD, SEM and XPS analysis confirmed the formation of ZnFeTiO4 inverse spinel structure. The electrical and dielectrical properties of ZnO/Zn2-xFexTiO4 (x?=?0.7, 1, 1.4) were measured by impedance spectroscopy, revealing a decrease in the electrical conductivity and the dielectric constant with Fe content.
MgF2 coating solutions were solvothermally treated at 160?°C for different time periods, this procedure induced crystallization and particle growth. Antireflection coatings prepared on glass from these solutions were compared to films derived from untreated precursor material. Ellipsometric porosimetry (EP) was employed to characterize structural features of coatings on glass as function of annealing temperature. Based on precursor solutions that had undergone solvothermal treatment antireflective coatings with a peak transparency exceeding 99% were prepared on PMMA substrates.
Solvothermal treatment of MgF2 precursor solutions results in crystallization of particles that can directly be applied to PMMA substrates for λ/4 antireflective films.
Bismuth ferrite (BiFeO3, BFO) as a prototype multiferroic has been extensively studied in past years; however, there are several key issues not to be clearly expressed. Especially, the relationship of structure and physical properties still remains obscure. In this case, the interband electronic structure of BFO was elaborately manipulated by appropriation dopants of Ni and Gd to realize the huge saturated ferroelectric polarization in the polycrystalline films. For instance, a huge saturated polarization PS of 96?μC/cm2 and remnant polarization Pr of 91?μC/cm2 were achieved in Bi0.925Gd0.075Fe0.95Ni0.05O3 film. The results and analysis show that the alteration in the interband electronic structure and the improvement of morphology derived from the ion doping effect indeed play key roles on the improved ferroelectric property of the doped BFO films. The decreased leakage current density and thereby the enhanced ferroelectric polarization in the doped BFO films should be attributed to the decrease in both Fermi level and Urbach energy closely related with the defects, as well as the improved surface uniformity and compactness of the films. Finally, the mechanism and relationship of structure and physical properties in BFO were systemically analyzed and discussed.
Pure and Ag-doped zinc oxide sol–gel thin films were prepared by spin-coating process. Pure and Ag–ZnO films, containing 2–8% Ag, were annealed at 500?°C for 2?h. All thin films were prepared and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), and UV–visible spectroscopy. X-ray diffraction studies show the polycrystalline nature with hexagonal wurtzite structure of ZnO and Ag:ZnO thin films. The crystallite size of the prepared samples reduced with increasing Ag doping concentrations. AFM and SEM results indicated that the average crystallite size decreased as Ag doping concentration increased. The transmittance spectra were then recorded at wavelengths ranging from 300 to 1000?nm. The films produced yielded high transmission at visible regions. The optical band gap energy of spin-coated films also decreased as Ag doping concentration increased. In particular, their optical band gap energies were 3.75, 3.55, 3.4, 3.3, and 3.23?eV at 0%, 2%, 4%, 6%, and 8%, respectively. Antibacterial activity of pure and Ag-doped zinc oxide against Escherichia coli and Staphylococcus aureus was evaluated by international recognized test (JIS Z 2801). The results showed that pure and Ag-doped ZnO thin film has an antibacterial inhibition zone against E. coli and S. aureus. Gram-positive bacteria seemed to be more resistant to pure and Ag-doped ZnO thin film than gram-negative bacteria. The test shows incrementally increasing in antibacterial activity of the thin films when dopant ratio increased under UV light.
Bismuth ferrite (BiFeO3) nanopowder have been successfully synthesized for the first time via a microwave-assisted sol-gel combustion method by using citric acid as fuel. The resulting nanopowder was characterized using FT-IR, TG-DTA, XRD, EDX, VSM, SEM, and UV-Vis DRS. A ferromagnetic hysteresis loop with a saturation magnetization (MS) of 0.66?emu?g?1 has been observed at room temperature in the sample. The optical properties of the nanosized BiFeO3 showed its small band gap (=2.08?eV) indicates a possibility of utilizing much visible light for photocatalysis.
Since the late 1960s, ceric hydrogen phosphates have attracted the attention of scientists due to remarkable ion exchange, sorption, proton-conduction and catalytic properties. In this work, through the application of various solvents, we, for the first time, have obtained monolithic aerogels based on ceric hydrogen phosphates with high porosity (~99%) and extremely low density (~10?μg/cm3). The composition and structure of aerogels were thoroughly studied with XRD, TEM, SEM, XPS, low temperature nitrogen adsorption methods, TGA/DSC, Fourier-transform infrared spectroscopy (FTIR) and small-angle neutron scattering (SANS). The aerogels were found to belong to the fibrous macroporous aerogels family.
CdO thin films were deposited on glass, quartz, FTO, silicon wafers of p-type and n-type at 200?°C of substrate temperature employing spray pyrolysis technique using nebulizer. As deposited cadmium oxide thin films were analyzed to find crystallite size, morphology of the substrate, elemental composition and band gap using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDAX) and UV–Vis spectrophotometer. Nature of the thin film was found to be polycrystalline with face centered cubic structure with (111) preferential orientation and evaluated structural parameters show significant effect of used substrates. Spherical sized grains were observed on the surface of the thin films using SEM. The EDAX analysis confirmed that cadmium and oxygen were present in the sample. Direct allowed transition with band gap values lying in the range 2.34–2.44?eV for all the films deposited on various substrates. Among, these thin film coated on FTO substrate was found to have high crystallinity with a narrow band gap, which may be more suitable for opto-electronic applications.
The absorption co-efficient spectra and inset of transmittance spectra with wavelength of CdO thin films at different substrates (Glass, Quartz and FTO).
Systematic studies of silica gels with covalently immobilized thiosemicarbazide and formazan groups under the conditions of competitive sorption from multicomponent systems were conducted. A methodological approach to determine the selectivity of the modified sorption material with regard to Cu(II), Ni(II), Co(II), Cd(II), and Zn(II) was proposed. Solid-phase extraction in equilibrium conditions of Cu(II), Zn(II), Co(II), Cd(II), and Ni(II) on a silica gel with covalently immobilized thiosemicarbazide and formazan groups in the conditions of competitive sorption was studied. The possibility to use the pseudo-second-order kinetic equation for assessment of mutual influence at competitive sorption has been shown. We found that sorption from multicomponent solutions proceeds as a non-additive process under the conditions of an excess of functional groups.
Degradation of three different endocrine disruptors (EDs) was thoroughly studied on prepared durable thin layers of titanium dioxide with an anatase crystalline structure. Specially constructed laboratory reactors bringing information on all individual processes (photolysis, photocatalysis, sorption) involved in decomposition of the studied EDs (17α-ethynylestradiol, bisphenol A and 4-nonylphenol) were applied. It was found that photolytic removal of EDs is the fastest degradation process; nevertheless, this method may be less effective regarding all indicators including toxicity. It was verified that individual degradation processes (photolysis and photocatalysis) showed a significantly different influence on toxicity of resulting solutions. During the photolytic process, EDs degradation caused increasing toxicity contrary to the photocatalytic process. Obtained results were corroborated by a mathematical model, which showed that a limitation step for photocatalysis is a sorption and for photolysis a toxicity of resulting products.
The mesoporous silica samples with different concentrations of phosphonic acid groups on the surface were obtained by direct template synthesis. The block-copolymer Pluronic P123 was used as a template, and sodium meta-silicate with diethylphosphatoethyltriethoxysilane as precursors. According to the SAXS diffractograms, mesoporous silica samples have a p6mm hexagonal symmetry. In addition, we used sol–gel method to synthesize xerogel with the same groups for comparison. All samples possess high values of specific surface area 615–730?m2/g and sorption pore volume. FTIR and potentiometric titration methods were used to investigate the surface layer of these samples. Sorption properties of the samples with phosphonic acid groups were studied in respect to a row of metal cations, among which we focused on lead(II), cadmium(II), and dysprosium(III) cations.
In this work, sol–gel-based non-stick ceramic coating formulations were prepared and coated onto aluminum panels in order to investigate their surface properties. The effect of the addition of optimal amount of fluorine-containing silane compound (FAS) on the surface and adhesion properties were also investigated. The morphology, structure, and elemental chemical composition of the coatings were characterized by scanning electron microscopy, atomic force microscopy (AFM), energy dispersion spectrum (SEM/EDAX), Fourier-transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS), respectively. Moreover, several properties of the coatings such as cross-cut adhesion, hardness, gloss, and contact angle (CA) were determined. When fluorine was introduced, the pencil hardness was increased to 6H. Fluorinated non-stick ceramic coatings were found to have good adhesion on the aluminum substrates.
Fiber needle felt–silica aerogel composite was successfully prepared by via sol–gel process based on water glass. The thermal conductivity show V-type variation tendency with the increase of water to Si. Thermogravimetric analysis-differential scanning calorimetry analysis revealed that the thermal stability was up to approximately 390.58?°C. It has been found that the fire hazard of the composites decreased with the increased ratio of water to Si according to the cone calorimeter test, which can be characterized by peak heat release rate, fire performance index, and fire growth rate index. The fiber needle felt/aerogels present greatly improved compressive and flexural strength (elastic modulus: 0.1–0.97?MPa; flexural modulus: 0.33–0.66?MPa) while keeping inherent properties of pure silica aerogel: low bulk density (0.166?g/cm3), low thermal conductivity of 0.0236?W/m·K, and high specific surface area (1091.62?m2/g). As a result, the as-prepared composite shows a great potential to be applied in the thermal insulation field.
In the present study, TiO2/ZnO composite nanodot films were prepared and the effects of Zn incorporation on light-induced cell detachment were investigated. The nanodots films, which were successfully synthesized by phase-separation-induced self-assembly method, were characterized on the morphology, composition, microstructure, and other properties, and evaluated on cell compatibility and cell detachment performances as well. Live-dead staining was used to study the viability of cell sheet detached by light illumination. Results shows that with the increasing of introduced Zn, the band gap widened and the absorbance in UV region increased, while the crystallinity and performance of light-induced hydrophilicity weakened. All the nanodots films showed good cell compatibility and cell detachment performance induced by light. The nanodots film which had a Zn/Ti molar ratio of 0.03 showed the highest detachment ratio of 91.0% after 20?min ultraviolet illumination. The prepared TiO2/ZnO composite nanodots films could be helpful in optimizing light-induced cell detachment behavior.
