Influences of preferred orientation growth on electrical properties of ZnO:Al films by sol–gel method

Using different precursor preparation, heating methods, and initial layers, this work investigated the relation between the micro-structural and electrical properties of ZnO:Al (AZO) films prepared by sol–gel method on glass and silicon substrates. It was found that adding monoethanolamine (MEA), using initial layers, or an intentionally produced steep temperature gradient obviously promoted film growth along the (002) direction. However, the carrier mobility rose only a little while the carrier concentration was not affected or even reduced. Generally speaking, the film conductivity was not evidently improved. It could be concluded that all three methods are advantageous for enhancing the crystallographic quality and therefore the mobility of the AZO films, but the major reason for the poor conductivity of the sol–gel derived ZnO films was the low activation of the dopant, which is the key factor for further improvements and should be solved first.     

Crystallization kinetics of MgO–Y2O3 composite nanopowder synthesized via combustion sol–gel method

Journal of Thermal Analysis and Calorimetry - The aim of this study is to synthesize MgO–Y2O3 nanocomposite by combustion sol–gel method from sucrose as a combustion agent. The...     

Photo-assisted electrodeposition of sol–gel films on p-type semiconductors

A new approach for the deposition of sol–gel films on semiconducting substrate using photo-electrochemical technique is presented. The deposition is based on accelerating sol–gel condensation reaction by the catalyzing effect of electrochemically generated OH⁻ ions when applying both negative potentials and light irradiation onto p-type semiconductors. Results show that both the negative shift in potential and the increase in light intensity facilitate the deposition kinetics of silica sol–gel films. Surface patterning is further achieved with the assistance of a laser.     

Preparation of a visible light-driven Bi2O3–TiO2 composite photocatalyst by an ethylene glycol-assisted sol–gel method,and its photocatalytic properties

A visible light-driven Bi₂O₃–TiO₂ composite photocatalyst was prepared by an ethylene glycol-assisted sol–gel method in which ethylene glycol acted as a polycondensation agent to capture metal ions by reacting with bismuth and titanium sources via a complex polycondensation pathway. The photocatalyst was characterized by X-ray photoelectron spectroscopy, X-ray diffraction, acquisition of N₂ adsorption–desorption isotherms, transmission electron microscopy, and UV–visible diffuse reflectance spectroscopy. The results revealed that the Bi₂O₃–TiO₂ composite was of smaller particle size, greater specific surface area, and had stronger absorbance in the visible light region than pure TiO₂. The photocatalytic activity of the as-prepared catalyst was evaluated by degradation of rhodamine B under visible light irradiation (λ > 400 nm); the as-prepared Bi₂O₃–TiO₂ composite was substantially more active than pure TiO₂. This was ascribed to the high surface area and the heterojunction structure.     

Novel photoconductive Ag/nanostructure ruthenium oxide/p-type silicon Schottky barrier diode by sol–gel method

A new Schottky photodiode of Ag/RuO₂/p-Si/Al was successfully fabricated using spin-coating technique. The ruthenium oxide (RuO₂) nanoparticles with an average size of 8 nm were synthesized using a sol–gel method. The crystal structure and morphology of the synthesized RuO₂ were analyzed by means of X-ray diffraction, energy dispersive X-ray spectroscopy, transmission electron microscopy and selective area electron diffraction. The rectification ratio of the diode was found to be 112 at ±2 V. The ideality factor and barrier height values of the Ag/RuO₂/p-Si/Al diode were obtained to be 1.47 and 0.55 eV, respectively. The Cheung–Cheung and Norde’s models were used to determine the diode parameters. The photoresponse behavior of the fabricated Ag/RuO₂/p-Si/Al diode was studied under various illumination intensities. The transient photocurrent results indicate that photocurrent under illumination is higher than the dark current and this indicates that the fabricated diode behaves as a photodiode. The capacitance–voltage–frequency measurements indicate that the capacitance of the diode depends on voltage and frequency. The obtained results suggest that the new Ag/RuO₂/p-Si/Al diode can be used an optical switching device for optical sensor applications and are also expected to be generated in the future study.     

Preparation and characterization of In2O3/ZnO heterostructured microbelts by sol–gel combined with electrospinning method

Long and thin In₂O₃/ZnO heterostructured microbelts were synthesized by sol–gel combined with electrospinning process. The as-prepared microbelts show the well defined one-dimensional belt structures with 1–5 μm in width and tens of millimeters in length. The polycrystalline microbelts calcined at 973 K for 1 h are still continuous and have the uniform rectangular cross sections and the thickness to width ratio is around 1:10. The crystalline phases of samples are investigated by X-ray diffraction and the morphology is examined using transmission electron microscope and scanning electron microscope. In₂O₃/ZnO heterostructured microbelts exhibit the excellent visible photocatalytic property in the photodegradation of methyl orange (MO), and over 94 % of MO was degraded within 3 h.     

Study on the synthesis of ZnO/K2SO4 composite material by sol–gel method and its photocatalytic properties

A novel photocatalytic composite material ZnO/K₂SO₄ was prepared using sol–gel method. The samples were characterized by means of wide-angle X-ray diffraction, Fourier-transform infrared spectroscopy, and high-resolution scanning electron microscopy. The preliminary experimental results indicated that the as-prepared composite material exhibited good photocatalytic performance in the degradation of methyl orange in aqueous solution. The results indicate that 92.54% of the initial methyl orange was degraded after 30 min of ultraviolet light irradiation by adding 0.15 g ZnO/K₂SO₄ composite material into 50 mL methyl orange solution.     

Synthesis of novel ZnAl2O4/Al2O3 nanocomposite by sol–gel method and its application as adsorbent

Journal of Sol-Gel Science and Technology - In this research, ZnAl2O4/Al2O3 nanocomposites with different ZnAl2O4 (30, 50, and 70?wt.%) were successfully prepared in one step by sol–gel...     

Optical properties of yellow-light-emitting LiZnVO4:Eu3+ phosphor prepared by sol–gel method

Europium-doped nanocrystals of lithium zinc vanadium oxide (LiZnVO₄) prepared via the sol–gel method are characterized. The X-ray power diffraction results reveal that a pure phase is obtained at 500 °C. The photoluminescence spectra of LiZnVO₄:xEu (x = 7 mol%) exhibit emission peaks at 526, 597 and 620 nm. The emission shifts from bluish-green to yellow when the doping concentration is increased from 0 to 7 mol%, due to the emission peak at 620 nm from the ⁵D₀ → ⁷F₂ transition, which originated from charge transfer transitions from VO₄ ^3? to Eu³⁺ ions.     

Synthesis of SnO2 nanostructures by ultrasonic-assisted sol–gel method

Fluorine doped SnO₂ nanostructures were grown using ultrasonic assisted sol–gel method. The gel was obtained by dissolving stannous chloride in methanol with ammonium fluoride as dopant followed by irradiation with ultrasonic vibrations. Obtained samples were characterized by structural, morphological and optical studies. All the peaks in the X-ray diffractograms are identified and indexed as tetragonal cassiterite structure. Negative slope of Williamson–Hall plots indicates compressive strain. Particle size of SnO₂ nanostructures is decreases with increases in concentration of fluorine doping. Atomic force microscopy, scanning electron microscopy and transmission electron microscopy studies confirm the formation of ring like porous structures and then hollow tube like growth with increase in the fluorine concentration. Peaks in Raman spectra also indicate strong confinement in SnO₂ particles. Distinct peaks in the PL spectra make the structure suitable for photovoltaic applications.     

Microstructure and dielectric properties of Nd doped CaCu3Ti4O12 synthesized by sol–gel method

Ca_(1?3x/2)Nd _x Cu₃Ti₄O₁₂ (x = 0, 0.1, 0.2 and 0.3) powders and ceramics were prepared by sol–gel method. Effect of Nd on microstructure and dielectric properties were investigated. XRD patterns suggest that pure perovskite-like CCTO phase were obtained after calcining at 800 °C for 2 h. SEM pictures reveal that particle size monotonously decreases from 250 to 120 nm with increase of Nd concentration. The lattice parameters show an increasing trend with the enhancing amount of Nd³⁺ substitution. The average grain size of CCTO ceramics decrease from 2.0 to 0.8 μm with increase in Nd doping, which indicates that high concentration of Nd inhibits grain growth of CaCu₃Ti₄O₁₂. Both of the dielectric constant and dielectric loss decrease with increase in Nd concentrations. Ca_(1?3x/2)Nd _x Cu₃Ti₄O₁₂ ceramics with x = 0.3 shows the lowest dielectric constant of 1.12 × 10⁴ as well as the lowest dielectric loss value of 0.12 at 20 °C(10 kHz).