Sol Gel Dip-coating Method Research Articles

Improvement of Properties of Stainless Steel Orthodontic Archwire Using TiO2:Ag Coating

Orthodontic treatment carries the risk of major complications such as enamel demineralization, tooth decay, gingivitis, and periodontal damage. A large number of elements of fixed orthodontic appliance results in the creation of additional plaque retention sites which increase the risk of biofilm creation. Modification of the surface of orthodontic elements may prevent the formation of bacterial biofilm. In this paper, surface modification of stainless steel orthodontic wires with TiO2: Ag was carried out by the sol-gel thin film dip-coating method. To obtain the anatase crystal structure, substrates were calcined for 2 h at 500 °C. The properties of the obtained coatings were investigated using scanning electron microscopy, X-ray diffraction, and electrochemical tests. Corrosion studies were performed in a Ringer’s solution, which simulated physiological solution. SEM and XRD analyses of the coated surface confirmed the presence of Ag nanoparticles which may have antimicrobial potential.

Low-Temperature Synthesis of Vanadium Dioxide Thin Films by Sol-Gel Dip Coating Method

The vanadium dioxide (VO2) thin films were synthesized by sol-gel dipping on a glass slide substrate at low temperature of 500°C in a vacuum tube furnace at a pressure of 2 × 10−3 mbar by 2-step calcination without an intermediate gas purging. Synthesis conditions, including temperature, vacuum pressure, and calcination steps in the vacuum tube furnace, were investigated to find the optimum condition that promoted the formation of VO2 phase. It was found that the 2nd calcination step was very important in realizing the monoclinic vanadium dioxide (VO2 (M)). The results of the valence electron analysis revealed the outstanding phase of VO2 and a small amount of V2O5 and V2O3 phases. The small crystallites of the VO2 were homogeneously distributed on the surface, and the grain was of an irregular shape of ∼220−380 nm in size. The film’s thickness was in a range of 69−74 nm. The film exhibited a metal-to-insulator transformation temperature of ∼68oC and good thermochromic property. Visible optical transmittance remained at ∼40−50% when the sample’s temperature changed from 25 to 80°C for a near infrared (NIR) region.

Investigation of structural, optical, antibacterial, and dielectric properties of V-doped copper oxide thin films: Comparison with undoped copper oxide thin films

Vanadium doped Copper oxide (CO) thin films were prepared by the sol-gel dip-coating method. The properties of thin films were examined by X-Ray Diffractometer (XRD), UV–Visible-NIR spectrophotometry, and dielectric properties analyzer. The antibacterial and photocatalytic properties were also determined. XRD spectra revealed the dual-phase of copper oxide (cuprite and tenorite) for all percentages of V with no other impurity peak. Tauc's relation is used to probe the optical band gap which is reduced from 1.96 to 1.64 eV with an increase in vanadium doping percentage. The impurity band coalesces with the conduction band of copper oxide to decrease the band gap. Dielectric constant measurements reveal that the Ac conductivity of thin films increases with an increase in V doping percentage.

Structural investigations of ZnO nanostructure

Undoped and Mn-doped ZnO samples with different percentages of Mn content (1, 5 and 10 at%) were synthesized by a dip coating sol–gel method. We have studied the structural, chemical and optical properties of the samples by using X-ray diffraction (XRD), scanning electron microscopy (SEM) and UV-visible spectroscopy. The XRD spectra show that all the samples are hexagonal wurtzite structures. We note that doping favors c-axis orientation along (002) planes. Up to 5 at% of Mn doping level, the c- axis lattice parameter shifts towards higher values with the increase of manganese content in the films. The expansion of the lattice constant of ZnO–Mn indicates that Mn is really doped into the ZnO. The SEM investigations of all samples revealed that the crystallites are of nanometer size. The sur- face quality of the ZnO–Mn film increases with Mn doping but no significant change of the grain size is observed from SEM images. The transmittance spectra show that the trans parency of all the samples is greater than 85 %. We note, also, that a small doping (1 %) lowered the refractive index while the thickness of the layers and the gap increase. However, on raising the proportion of Mn beyond 5 %, practically the same values of index and gap as pure ZnO are found.

Effect of Co Doping on the Functional Properties of MnO2 Thin Films

Thin films of Co-doped [Formula: see text]-MnO2 have been deposited on Pyrex glass substrates by the sol–gel dip-coating method with Co concentrations of 1, 3, 5 and 7 at.%. The deposited thin films were characterized for their structural, morphological, optical and electrical properties. The XRD spectra confirm that all the samples have tetragonal phase of [Formula: see text]-MnO2. FTIR spectra reveal the presence of Mn–O in all of the samples. AFM measurements indicate that the surfaces of films have been affected with cobalt content incorporation. Transmittance spectra of the undoped and Co-doped MnO2 thin films were recorded by a UV–vis spectrometer. Optical gap was found to be in the 2.60–2.51-eV scale. This decrease is due to the presence of manganese vacancies and/or oxygen defects. From the complex impedance measurements that show semicircular arcs at different cobalt contents, an equivalent parallel [Formula: see text] electrical circuit has been proposed.

Effect of Sn doping concentration on structural, optical and electrical properties of ZnS/p-Si (111) diodes fabricated by sol-gel dip-coating method

Tin doped zinc sulfide (ZnS:Sn) thin films have been fabricated by sol-gel dip-coating method on glass and p-Si substrates by varying Sn concentration between 0 wt % and 10 wt %. The structural and optical properties of ZnS:Sn thin films have been studied by X-ray diffraction and spectrophotometer measurements. X-ray results show the films grown on glass and p-Si substrate are cubic structure. Optical band gap values found from the transmittance spectra have decreased from 3.58 eV to 3.42 eV with the addition of Sn. The effect of tin concentration on the device performance of ZnS:Sn/p-Si has been investigated through the analysis of the I–V characteristics under dark and illuminated conditions. Diode parameters such as ideality factor n, barrier height Φb, saturation current Io, series resistance value RS have been calculated by means of thermionic emission theory, and Norde method. Photosensitivity PS, photoresponsivity R, and detectivity D values of the diodes have been determined from I–V measurements under 100 mW/cm2 illumination intensity. It has been determined that 3% Sn doped ZnS/p-Si diode showed the best diode and photodiode properties among Sn doped ZnS/p-Si diodes.

The influence of doping lead and annealing temperature on grown of nanostructures of TiO2 thin films prepared by a sol-gel method

Pb+2-doped TiO2 thin films were prepared by a sol-gel dip-coating method on silicon substrate. The films were annealed at different temperatures (600–1000 °C) and at various thicknesses (68–120 nm). XRD, Raman and FTIR spectroscopy shows the crystallization of thin films on anatase, rutile and PbTiO3 phase, as annealing temperature increase from 600 °C to 1000 °C respectively. The SEM micrographs indicate that the morphology transform with increase of annealing temperature. At lower temperature we observed only anatase and rutile phase, with the increase of annealing temperature the formation of lead titanate (PbTiO3) take place. Photoluminescence and reflectance spectrum of Pb doped TiO2 thin films show absorption bands and a shift to higher wavelengths (lower energy). These results proved that doping lead in TiO2 modify the levels impurities and decreased the optical gap of TiO2 thin films which enhanced the optical properties.

The Use of Taguchi Method to Elaborate Good ZnO Thin Films by Sol Gel Associated to Dip Coating

ZnO thin films have been prepared by dip coating sol gel method using Taguchi technique. The underlying principle was to make something as little as conceivable the measure of examination and make sense of the best conditions for developing ZnO thin films with great properties. We used a trial plan of L9, with three levels (high, medium, low) and four elements (annealing temperature, precursor concentration, dip coating speed, annealing time). For each paper three sol-gel arrangements were arranged, and test is rehashed three time. We have chosen to carry out the optimization based on the gap energy calculated from the transmittance of the films obtained. Each sample was characterized with spectrophotometer. This characterization allowed us to draw the transmittance curve and to deduce the gap energy of each deposited ZnO thin film. A signal to noise and an analysis of variance (ANOVA) were used to determine the optical and electrical properties. The film that we obtained with the optimal condition was exanimated by using the characterization methods like UV-visible spectroscopy, X-ray diffraction, SEM (Scanning Electron Microscopy) and EDS (Energy Dispersive Spectroscopy). With the legal statement under oath condition, ZnO thin film showed high crystal quality and the transmittance is a greater amount of 90%.

DESIGNING AND FABRICATION OF A LOW-COST DIP-COATER FOR RAPID PRODUCTION OF UNIFORM THIN FILMS

In this work, a self-made dip-coater equipment was developed for the fabrication of thin films. The assembly of the apparatus was carried out using simple mechanical and electronic pieces, recycle parts, and spending an inexpensive budget suitably. The production, software design, and features of the device were focused on the sol-gel dip-coating method, which involves gravitational draining and drying processes, as well as continued condensation reactions. The dip-coater was based on the Arduino microcontroller and a step motor. The immersion speed in the solution, the waiting time, and the withdrawal process were typed by a digital control panel, where the optimal range found for speed was 0.1 – 6.0 mm s-1 without vibration interferences. The total fabrication cost of the fabricated dip coater was less than 100 USD and the assembly process was not complicated. Finally, the performance of the dip-coater was evaluated through the deposit of copper oxide and iron oxide films on fluorine-doped tin oxide glass substrates layer by layer. The field emission scanning electron microscopy cross-section images confirm the formation of thin films with thickness in the nanoscale range, with good stability and sameness achieved through the control thickness during the dip-coating method under ambient conditions.

Synthesis and characterisation of nano TiO2 film for enhancing antireflection properties

ABSTRACT A nanostructured TiO2 thin film was deposited on glass substrate by using sol gel dip-coating method to improve the antireflective property and performance of the solar PV cell. In this way, TiO2 was prepared by using titanium isopropoxide (TIP) as precursor and nitric acid (HNO3) as catalyst and the corresponding structural and optical properties were studied. The film thickness was tailored by varying the withdrawal rate. The X-ray diffraction results showed that TiO2 thin film calcined at 300°C was amorphous, and was transformed into anatase phase at 450°C with crystallite size of 22.6 nm. The microstructure of the film was analysed by Scanning Electron Microscope (SEM) and the elemental composition was confirmed by Energy Dispersive X-Ray Analysis (EDAX). The surface topography was characterised by Atomic force microscopy (AFM) which reveals that the surface has many spikes which confirms the surface is not smooth. The optical properties such as absorption and reflection were investigated by using UV-VIS spectrometer which indicates that the absorption was increased from 1.2% to 1.5% at the wavelength range from 250 to 314 nm and the reflectance was reduced from 23% to 5.7% after the TiO2 deposition and the conversion efficiency was increased from 14.22% to 17.54%.

Effect of Transition Metals on the Mechanical Properties of ZnO Thin Films, Prepared by Sol-Gel Method

Undoped and transition metals (TM = Cr, Ni, Mn and Cd) doped zinc oxide (ZnO) thin films were prepared by sol-gel dip-coating method on glass substrates at 300 °C. In this study, the effect of dopant material on the structural, morphological, optical, electrical and mechanical properties of ZnO thin films is investigated by using XRD, AFM, UV-Vis, Hall effect and nanoindentation techniques, respectively. Nanocrystalline films with a ZnO hexagonal wurtzite structure and two preferred orientations (002) and (103) were obtained. UV-Vis transmittance spectra showed that all the films are highly transparent in the visible region (> 80 %). Moreover, the optical band gap of the films decreased to 3.13 eV with an increasing orbital occupation number of 3d electrons. AFM-topography shows that the films are dense, smooth and uniform, except for the high roughness RMS =26.3 nm obtained for Cd-doped ZnO. Finally, the dopant material is found to have a significant effect on the mechanical behavior of ZnO as compared to the undoped material. For Ni and Cd dopants, analysis of load and unload data yields an increase in the hardness (8.96 ± 0.22 GPa) and Young’s modulus (122 ± 7.46 GPa) of ZnO as compared to Cr and Mn dopants. Therefore, Ni and Cd are the appropriate dopants for the design and application of ZnO-based nanoelectromechanical systems.

Enhanced osteogenesis properties of titanium implant materials by highly uniform mesoporous thin films of hydroxyapatite and titania intermediate layer.

Titanium (Ti) has been widely used for medical and dental applications; however, bare Ti cannot be properly connected to a living bone, and hence some modifications are needed for this purpose. The present study describes the synthesis of mesoporous hydroxyapatite thin films (MHF) on titanium implant materials for speeding up and shortening the processes of osteointegration. The uniform MHF was coated on a Ti substrate following the insertion of intermediate titania (TiO2) film via the sol-gel dip-coating method. The intermediate titania layer improved the bonding strength between the MHF and Ti substrate. MHFs were synthesized using a precursor solution containing phosphoric acid, calcium nitrate tetrahydrate, and a nonionic surfactant (C12E10) as the phosphate source, calcium source, and structure-directing agent, respectively. The effect of calcination temperature on phase composition, morphology, microstructure, roughness, and wettability of the MHFs was investigated using XRD, FE-SEM, COM, AFM, and contact angle measurement. The XRD results revealed the crystalline hydroxyapatite phase, which was improved with an increase in the calcination temperature. Moreover, the FE-SEM images showed the crack-free MHFs, uniform thickness of the layer, and mesoporous surface morphology. In addition, it was found that the roughness and wettability of the samples change upon the alteration of calcination temperature. The biological studies demonstrated that MHFs support the adhesion and proliferation of the mesenchymal stem cells (MSCs) and guid them toward osteogenic differentiation. Therefore, the MHFs prepared in this study may be useful in a wide range of applications, particularly in bone regeneration medicine.

Gaining thermochromic property of quartz lamel surface and functionalization

The aim of this study was to obtain functional features by coating the quartz lamella with a sol-gel technique. Smart functional material was developed by including microencapsulated thermochromic pigments in coatings. Using anatase powder titanium (IV) oxide with additions in different ratios, the coatings were applied to the quartz lamel surfaces by dip-coating technique. The sol formulation was made using the initial precursors Tetraethoxysilane (TEOS) and 3-aminopropyltriethoxysilane (APTES). Tetraethoxysilane was added to the structure of the coatings to increase the adhesion of the coatings to the substrate. Thermochromic coatings were synthesized by reacting polyvinylpyrrolidone in aqueous solution with tetraethoxysilane. The structural and thermochromic performance of coatings prepared with the sol-gel dip-coating method was systematically characterized and its functionality was determined. In this study, the effects of the addition of titanium (IV) oxide on the phase composition, transition temperature, and surface morphology of the coatings were investigated. The result obtained showed that the formed anatase phase increased as the titanium (IV) oxide content increased. Exothermic and endothermic transition temperatures for the undoped sample ranged from 34.6 °C to 26.5 °C, while 3 g titanium (IV) oxide doped sample these temperatures varied from 34.6 °C to 26.7 °C. Smooth surface coatings were prepared using polyethylene glycol. The results demonstrated that the colors of the obtained thermochromic coatings could be reversibly changed between green and white.

High quality semiconductor Cd2SnO4 films for solar cell applications

In this work, we study the effect of Ar/CdS annealing treatment on physical properties of semiconductor Cd2SnO4 (∼260 nm thick) films. The films were produced by sol–gel dip-coating method and annealed at 450 °C ≤ T a ≤ 650 °C. A full characterization of the optical, electrical, and structural properties, and a discussion of the mechanism that yield enhanced physical properties is presented. All annealing treatments explored led to the improvement of physical properties of the semiconductor films. However, values of electrical resistivity of 6 × 10−4 Ω-cm, carrier concentration of 3 × 1020 cm−3 and mobility of 35 cm2 Vs−1 were reached at T a = 650 °C, without compromising the optical properties (T ≥ 85% for 450 ≤ λ ≤ 1200 nm). These represent an improvement of almost 6-fold over untreated films. Although the Moss–Burstein effect leads to a band gap of 3.5–3.7 eV, the fundamental band gap was estimated to be 3.3 eV. Moreover, the computed work function, 4.7–4.4 eV, indicates that these films can be used as transparent conductive oxide to design high-efficiency CdS/CdTe thin-film solar cells due to the smooth match of Fermi level with CdS coupled layer.

Anatase–Rutile Transition and Photo-Induced Conductivity of Highly Yb-Doped TiO2 Films Deposited by Acid Sol–Gel Dip-Coating Method

A method to prepare Yb-doped TiO2 is proposed, using titanium isopropoxide and ytterbium oxide. Thin films and powders are produced through the sol–gel technique where the Yb concentrations are 0.01 at.%, 0.02 at.%, 1 at.%, 2 at.% 4 at.% and 8 at.%. The increase in the doping concentration intensifies gradually the sample transparency for the whole observed spectrum and reaches the transparency degree of the undoped sample with the highest concentration of ytterbium. By means of x-ray diffraction (XRD) we find that the solution’s pH leads to the formation of a rutile structure which is compensated for by lanthanide doping, inhibiting the anatase–rutile phase transformation. Then, the XRD profile depends on the Yb concentration, being mostly anatase for undoped and highly (8 at.%) doped samples, with mixed ratios of these two phases in other concentrations. Maintaining an acid solution leads to fewer intergrain defects in the rutile structure contributing to higher conductivity. Photo-induced investigation of 8 at.% Yb-doped thin film, using several light sources leads to distinct behavior concerning the excitation of intra-bandgap states and/or electron–hole pairs. This result helps to understand the electronic transport in Yb-doped TiO2 and shows that devices based on its conductivity may have improved performance by irradiation with controlled light energy.

Microstructure and optical properties of TiO2- and HA-coated Ti6Al7Nb alloy by sol–gel method

In this study, the combination of titanium dioxide (TiO2) and/or hydroxyapatite (HA) coatings on Ti6Al7Nb titanium alloy to be used as an implant was performed in different solution retention times by the sol–gel dip-coating method and the characterization and optical properties of these coatings were investigated. Two different coatings were made on the substrate, the first group of samples was first coated with TiO2 and then with HA, while the second group of samples was coated with TiO2 alone. Before sol–gel coating, the samples were rinsed in distilled water and dried at 200°C for 2 h. The samples were immersed perpendicular to the coating solution. Thin films were obtained at a draw rate of 2 mm s−1. Microstructure investigations of the prepared coatings were examined under optical and scanning electron microscopes, while solid-state elemental fractions were determined by energy-dispersive X-ray spectroscopy analysis. Fourier-transform infrared spectroscopy analysis was performed to determine the functional groups placed on the surface of the material. The optical properties of the material were determined by UV analysis.

Synergetic Surface Behavior of Sol–Gel ZrO2–Nb2O5 Coated 316L Stainless Steel for Biomedical Applications

The porous outer layer and compact inner layer of zirconium/niobium mixed oxide coatings were deposited on medical grade 316L stainless steel by sol gel dip-coating method. The obtained coatings were homogeneous and polyphased crystalline in nature. The Scanning Transmission Electron Microscopy analysis revealed that the distribution of zirconium and niobium were uniform over the coated film. The Field Emission Scanning Electron Micrographs exhibited fine pores on the outer surface of the mixed oxide coating. Further, these pores were not directly connected to the 316L stainless steel substrate, which was evinced by the Scanning Electron Micrograph cross-sectional analysis. The corrosion performance of zirconium/niobium mixed oxide coated 316L stainless steel was evaluated by electrochemical techniques in simulated body fluid solution. The zirconium /niobium mixed oxide coating exhibited an enhanced corrosion resistance for 316L stainless steel as indicted by the reduced current density and enhanced corrosion potential toward the noble direction. The formation of synergetic and stable zirconium/niobium mixed oxide coating was proposed to account for enhanced corrosion protection and bioactive behavior for the long-term implant applications.

Hierarchical architecture of a superhydrophobic Cd-Si co-doped TiO2 thin film

Superhydrophobic coatings have various applications in the industries for successful control and removal of droplets from the surface. Hierarchical structures are promising to achieve a superhydrophobic surface. We fabricated a Cd-Si co-doped TiO2 hierarchical coating on the surface of a glass slide, exhibiting superhydrophobic properties. Cd-Si co-doped TiO2 thin films were prepared by a sol-gel dip-coating method. The morphology, the dominant TiO2 phase, and the crystal structure of the thin films were studied by the concentration of the Si dopant and the calcination temperature. Accordingly, the optical bandgap, surface chemical ligands, and surface topography of thin films also investigated. The lowest bandgap energy (3.23 ± 0.004 eV) was obtained for the sample with 5 wt% Cd and 20 wt% Si. Moreover, by increasing the calcination temperature of a sample with 5% Cd and 10% Si, the water contact angle was increased from 112.2° ± 6° to 168.5° ± 7°, due to the synergy effect of surface ligands and hierarchical structure.

Synthesis and Characterization of Thin TiO2 Films Using the Sol-gel dip Coating Method

TiO2 titanium oxide is a material with many applications, due to its electronic and optical properties, the characterization of the nanostructures developed with this material is carried out in order to determine its physical, chemical, and mechanical properties. This article presents the results of TiO2 multilayered thin film deposited in Corning glass substrate with the immersion technique using the Sol-gel dip coating method. The quality of the film strongly depends on the internal forces of the polymeric chains which lead to viscosity, gravitational force, surface tension, and gravity as an efficient form of obtaining TiO2 thin film. The film was submitted to thermal treatment of 400 ºC for 2 hours. The results of the experiment show film with a thickness from 139 to 171 nm that features anatase phase, a crystalline quality that corresponds to the number of deposited layers and have a bandgap close to 3.5 eV. The results show that TiO2 thin film can be used in applications that require high permittivity or high transmittance.

Scrutinizing the vital role of various ultraviolet irradiations on the comparative photocatalytic ozonation of albendazole and metronidazole: Integration and synergistic reactions mechanism

Herein, TiO2 nanoparticles were immobilized on the ceramic surface using the sol-gel dip-coating method, which confirmed by scanning electron microscopy (SEM) and atomic force microscopy (AFM). Then, a semi-batch reactor containing the prepared ceramic plates, which irradiated by the various UV lights was used for the degradation of the albendazole (ALZ) and metronidazole (MTZ) pharmaceuticals by the photocatalytic ozonation process. The control experiments were performed to compare the photocatalysis, ozonation, photo-ozonation and photocatalytic ozonation processes under the same operational conditions with the UV-A, UV-B and UV-C irradiations. The synergistic effect of photocatalysis and ozonation was observed; moreover, the results revealed that the UV-A/TiO2/O3 had the highest efficiency for the ALZ and MTZ degradation owing to the synergistic heterogeneous reactions (SHRs), which led to more reactive oxygen species (ROS). The MTZ and ALZ degradation were probed by monitoring the dissolved ozone, oxygen and hydrogen peroxide concentrations during the various processes including the UV-A/TiO2/O3 process. The obtained results disclose that the ALZ degradation is lower than the MTZ due to its resistant nature with more direct attacks of the ozone in the bulk solution compared to the MTZ. Furthermore, the various compounds as the holes (h+) and ROS scavengers or ozone solubility enhancers were added to the reaction bulk to investigate the exact mechanism of the photocatalytic-ozonation. Eventually, the degradation intermediates of the pharmaceuticals generated in the photocatalytic-ozonation process were successfully recognized by the Gas chromatography–mass spectrometry (GC–MS) and the possible degradation paths were suggested for the degradation of pollutants considering the responsible ROS in each case.