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Single phase and highly transparent ZnO:Tb films with a Tb concentration from 0.41 at% up to 0.78 аt% were formed on glass and silicon substrates by sol-gel deposition. The influence of ultraviolet radiation on the structural and photoelectric characteristics of n-ZnO:Tb/n-Si structures has been studied. The appearance of a photoelectric effect under the influence of a bias voltage and UV radiation (405 and 278 nm) was established, with an increase in photo effect when irradiated with shorter wavelength UV radiation (278 nm). It was shown that the concentration of the Tb3+ dopant is the determining factor for increasing the UV photosensitivity of the structures. The experimentally established selective sensitivity of n-ZnO:Tb/n-Si structures to UV radiation with a wavelength of less than 405 nm demonstrates the possibility of their use in UV radiation detectors or sun-blind detectors. [ABSTRACT FROM AUTHOR]

The wet chemistry route has been developed to prepare calcium hydroxyapatite (Ca10(PO4)6(OH)2, (HA)) thin films on a silicon substrate using the novel low-temperature sol-gel and dissolution-precipitation approach. The calcium carbonate thin films on the silicon substrate were obtained by spin-coating technique when substrates were repeatedly coated with 10, 20 and 30 layers of sol-gel solution. The composites formed of crystalline and amorphous CaCO3 were obtained by calcination of the coatings for different time at 600°C. A dissolution-precipitation procedure was used for the preparation of calcium hydroxyapatite thin films on silicon substrate at 80°C. The obtained synthesis products were characterised by X-ray powder diffraction (XRD) analysis, scanning electron microscopy (SEM) and Raman spectroscopy. [ABSTRACT FROM AUTHOR]

Reports have recently been published on ultrathin biofluid barriers, which enable the long‐term measurement of biological signals and exhibit conformability on nonlinear surfaces such as skin and organs. However, inorganic‐ and organic‐based barriers have process incompatibility and high water permeability, respectively. Siloxane‐ (inorganic) based fluorinated epoxy (organic) hybrid materials (FEH) are demonstrated for bio‐fluidic barrier and the biocompatibility and barrier performance for flexible electronic systems as solution‐processed oxide thin‐film transistors (TFTs) on 1.2 µm thick polyimide (PI) thin film substrate is confirmed. FEH thin film can be patterned as small as 10 µm through conventional photolithography. The fabricated solution‐processed indium oxide TFTs with FEH barriers exhibit durable performance over 16 h with no dramatic change of transfer characteristics in phosphate‐buffered saline (PBS) environment. Furthermore, to realize FEH barriers for flexible systems, the solution‐processed indium oxide TFTs with FEH barriers on ultrathin PI substrate are demonstrated subjected to compression test and successfully measure the electrical properties with no irreversible degradation during 1000 cycles of mechanical testing in PBS. [ABSTRACT FROM AUTHOR]

Calcium phosphate (CP)-based biomaterials, especially nanostructured ones, show a high biocompatibility and increased biological properties. The coatings composed of stoichiometric hydroxyapatite have been extensively used to improve integration of metallic implants in the host bone. However, these coatings exhibited several drawbacks that limited their successful application. It was concluded in numerous articles that the sol-gel derived coatings can undergo cracking and delamination and are scarcely uniform. In this review article the recent advances on the sol-gel synthesis of different phosphate coatings and thin films are summarized. The attention is paid to coatings and thin films of calcium hydroxyapatite (CHAp), other phosphates, bioglasses and different composite materials. The state of the art, limitations, potentialities, open challenges, and the future scenarios for the application of CP bioceramics are highlighted in this study. [ABSTRACT FROM AUTHOR]

The microstructural relaxation caused by heat treatment of ion-irradiated silica-based thin films was investigated. Hybrid organic-inorganic silica-based thin films were synthesized via a sol-gel process and were irradiated with 125 keV H+ or 250 keV N2+ ions with fluences of 1015 or 1016 ions/cm2. Ion irradiation was followed by heat treatment at 1100 °C or 1350 °C in an inert Ar atmosphere. The microstructure of the irradiated films before and after heat treatment was studied with a combination of Raman and infrared spectroscopies. The results indicated that while ion irradiation led to a defective structure of silica and graphitic C nanodomains, subsequent heat treatment led to structural relaxation and atomic reconfiguration of both silica and C. After heat treatment at 1100 °C, the microstructure of the films consisted of nanocrystalline graphite and structurally relaxed silica. After secondary heat treatment at 1350 °C, most of the C within the films vanished and the film microstructure only consisted of α-cristobalite silica. [ABSTRACT FROM AUTHOR]

Abstract The properties of Ce-doped ZnO (CZO) thin films synthesized through sol-gel dip coating processing were evaluated. Five thin films were synthesized by increasing Ce percentage between 1–5 at. wt.%. The XRD study put forward that Ce doped ZnO displayed hexagonal wurtzite ZnO structure and Ce ions are embedded in the ZnO lattice successfully. Results showed that the crystallite size decreased, as the percentage of Ce in the ZnO increased. The lattice volume of the thin film was distorted in the presence of Ce. Broadening and shrinking of the band gap took place under different Ce doping concentrations due to generation of defects and appearance of secondary phase. All thin film has shown antibacterial activity. [ABSTRACT FROM AUTHOR]

We have developed a model for the formation of silica-containing synthetic functional materials with a hierarchical pore structure and a large specific surface area under self-assembly conditions of sol-gel processes. The model includes the formation of a three-dimensional core (of a cristobalite type) of sol particles consisting of joined polymorphoids in the form of n-membered rings and a continuous transition between fractal aggregate growth mechanisms, from diffusion-limited to cluster-cluster aggregation, followed by evolution culminating in spinodal decomposition. Hierarchical structures have been studied using three-dimensional simulation with Autodesk 3ds Max software. [ABSTRACT FROM AUTHOR]

Biosynthesis of silver nanoparticles (AgNPs) using plants is considered to be cost effective and more eco‐friendly than conventional techniques. In the authors' previous study, they reported the biosynthesis of AgNPs using fruit extract of Aegle marmelos which were of spherical shape and high crystallinity. In order to achieve enhanced synthesis, optimisation of process parameters influencing the yield of AgNPs has been carried out in this study. Box–Behnken design has been employed to optimise the parameters in order to enhance the synthesis of AgNPs. The antimicrofouling activity of the optimised AgNPs was determined by preparing AgNPs doped TEOS sol–gels (SNSGs) and evaluating their antibiofilm activity. In addition to this, antimacrofouling activity of the AgNPs was studied against molluscs viz. Patella sp. and Trochus sp. as model organisms. Anticrustacean assay was also performed with the larvae of brine shrimp (Artemia salina) as a model crustacean fouling organism. The results indicated that the AgNPs could completely inhibit the attachment of molluscs and significantly increased the percentage of mortality against crustacean fouling larvae. Thus, this study gives scope for the possible development of formulations containing AgNPs as effective antifouling agents that could prevent the adhesion of micro and macrofoulers thereby preventing marine biofouling. [ABSTRACT FROM AUTHOR]

Calcium hydroxyapatite (Ca(PO)(OH), CHAp) films were obtained on silicon nitride (SiN) substrate by a sol-gel method using a dip-coating technique. In the sol-gel process, ethylendiamintetraacetic acid and 1,2-ethandiol, triethanolamine, and polyvinyl alcohol were used as complexing agents and gel network forming agents, respectively. Calcium acetate monohydrate was used as Ca source. The samples were annealed at 650 °C for 5 h in air after each dip-coating procedure which was repeated 10, 20, and 30 times. The coatings were characterized using X-ray diffraction, scanning electron microscopy, atomic force microscopy, Raman spectroscopy, and contact angle measurements. Monophasic CHAp layers on silicon nitride (SiN) substrate were fabricated and characterized for the first time to the best our knowledge. Graphical Abstract: [ABSTRACT FROM AUTHOR]

Hydroxyapatite (Ca 10 (PO 4 ) 6 (OH) 2 ; HAp) coatings on titanium substrate were prepared by a sol-gel method combined with dip-coating technique. The influence of Ti substrate modification on the formation of HAp coatings was also investigated. To achieve a better quality of HAp coatings, Ti substrates were modified by adding a calcium titanate (CaTiO 3 ) sublayer or additional preheating at 650 °C. The thermal behavior of Ca-P-O and Ca-Ti-O precursor gels was investigated by thermogravimetric (TG-DTG) measurements. X-ray diffraction (XRD) analysis was employed to characterize the phase composition of synthesized coatings. Scanning electron microscopy (SEM) was used to study the morphological features of CaTiO 3 sublayers and HAp coatings surfaces. Contact angle (CA) measurements were used to evaluate the hydrophilic/hydrophobic properties of the end products. [ABSTRACT FROM AUTHOR]

Calcium hydroxyapatite (Ca 10 (PO 4 ) 6 (OH) 2 , CHAp) films were obtained on silicon substrates by a sol-gel method using a spin-coating technique. In the sol-gel process, ethylendiamintetraacetic acid and 1,2-ethandiol, triethanolamine and polyvinyl alcohol were used as complexing agents and gel network forming agents, respectively. The samples were annealed at 1000 °C for 5 h in air after each spinning procedure. Spin-coating and annealing procedures were repeated 5, 8 and 10 times. The coatings were characterized using X-ray diffraction (XRD), scanning electron microscopy- energy dispersive X-ray spectroscopy (SEM-EDX) and Fourier Transform infrared spectroscopy (FTIR). FTIR-spectroscopy allowed us to predict the formation of oxyhydroxyapatite Ca 10 (PO 4 ) 6 (OH) 2-2x O x on the Si substrate. Moreover, according to the FTIR results, the side phase β-Ca 3 (PO 4 ) 2 has been formed instead of α-Ca 3 (PO 4 ) 2 . In addition, the anhydrous dicalcium, phosphate phase CaHPO 4 was also detected spectroscopically. [ABSTRACT FROM AUTHOR]

The goal of this study was to demonstrate that sol–gel processing route is suitable for the fabrication of calcium hydroxyapatite (Ca 10 (PO 4 ) 6 (OH) 2 , CHA) thin films on Si substrate by spin-coating technique. The substrate was spin-coated by precursor sol solution 1, 5, 15 and 30 times. The samples were annealed after each spin-coating procedure at 1000 °C for 5 h in air. In the sol–gel process ethylendiamintetraacetic acid and 1,2-ethandiol, and triethanolamine and polyvinyl alcohol were used as complexing agents and as gel network forming agents, respectively. The coatings were characterized using X-ray diffraction (XRD) analysis, scanning electron microscopy (SEM), atomic force microscopy (AFM), Fourier transform infrared (FTIR) and Raman spectroscopies, profilometry and the contact angle measurements (CAM). It was demonstrated, that properties of calcium hydroxyapatite thin films depend on spinning and annealing times. [ABSTRACT FROM AUTHOR]

The optical and conductometric responses of sol-gel-based ZnO thin films with embedded 5% mol. Au or Pt nanoparticles (NPs) have been compared at different operating temperatures, to assess the effect of noble metal additions on to H2, CO and NO2 gases sensors response. The scanning electron microscopy and X-ray diffraction techniques have been utilized for morphological characterization of the crystal structures of the films after annealing at 400°C for 30 min and the effect of Au and Pt NPs additions on crystallite growth is discussed. Au NPs additions is effective to enhance the optical response to H2 and CO at 390 nm and in the 500-700-nm wavelength range at 300- °C temperature. No optical response to NO2 gas, even at low concentrations has been measured in the optical mode. The catalytic action of Pt NPs additions powerfully improves both the optical to H2 and CO at 390 nm, and the conductometric gas responses. Detection limits as low as 20-ppb NO2 and 50-ppm H2, in line with the best performances reported to the best of our knowledge in literature for ZnO-based sensors, have been measured in the conduction mode. Response times have been also compared, highlighting the positive effects played by Pt additions. [ABSTRACT FROM PUBLISHER]

In this letter, TiO2 thin films were prepared via sol-gel method and metal/semiconductor/metal ultraviolet (UV) detectors with Pt Schottky contact were fabricated. At 5 V bias, the dark current of the device was only 80 pA. Diffusion theory was adopted to analyze the low dark current mechanism, which is consistent with the experimental results. The device shows a remarkably reduced decay time of 41.53 ms. The low dark current and improved time response performance may be attributed to the high effective Schottky barrier between Pt and TiO2 film. High responsivity of 34.5 A/W was achieved at 300 nm UV light and the ratio of photocurrent to dark current is about five orders of magnitude, which is much larger than that of other semiconductor photodetectors. [ABSTRACT FROM PUBLISHER]

Abstract: Extruded plates of AZ80 magnesium alloy were coated with CeO2 and/or MgO ceramics by sol–gel processing. We investigated the effects of heat treatment conditions, under which the ceramic thin film was formed, on the mechanical properties and corrosion resistance of the substrates. Single layer (CeO2 or MgO) and double layer (CeO2/MgO) ceramic thin films were successfully formed from precursor solution by the sol–gel processing under optimal heat treatment, in which the AZ80 original substrates were age-hardened. The corrosion resistance of AZ80 magnesium alloy substrates evaluated by the salt water immersion test was found to be improved by ceramic coating and microstructural change of the original substrate during coating process. The double layer ceramic coating was superior to the single layer coatings in terms of corrosion resistance. The acquisition of corrosion resistance in AZ80 magnesium alloy substrates could be applied simultaneously by sol–gel processing, while the substrates were age-hardened by the heat treatment. [Copyright &y& Elsevier]

The present study was aimed to fabricate thin films of TeO2-based glasses by a sol-gel process. It was here demonstrated that to control the hydrolysis reaction of Te-alkoxide with a chelating agent of diethanol-amine and in low-humidity environment was important because the hydrolysis reaction was extremely rapid. As a result, transparent TeO2-TiO2 thin films were successfully formed by dip-coating and subsequent heat-treatment. TiO2 component was found to be effective not only for more moderate hydrolysis reaction but also for an increase of refractive index. Photoluminescence properties of Eu3+ ions in TeO2-TiO2 thin film were also investigated. [ABSTRACT FROM AUTHOR]

Abstract: A series of phosphors with composition La9.33−x−y−z Si6O24O2 (x=Er, y=Ce, z=Yb) with the silicate oxyapatite structure were synthesized by a sol–gel spin-coating technique. The products formed as well-crystallized laminae 6–8nm thick. Spectroscopic measurements in the near-infrared showed that excitation through Ce3+ enhances 1.53μm emission of Er3+ by a factor of 50, while the effect of Yb3+ is to quench the luminescence. [Copyright &y& Elsevier]

Abstract: The objective of this work is the synthesis of 20mol% Y2O3 doped ZrO2 thin films on crystalline silicon (Si) substrate from the aqueous Y–Zr–O nitrate–citrate sols dissolved in ethanol or isopropanol using spin-coating technique and the investigation of the morphological, structural and electrical properties. All obtained samples were repeatedly annealed at 800°C temperature after spin-coating procedure and fully characterized by X-ray diffraction (XRD) analysis. XRD data exhibited that nanosized Y0.2Zr0.8O2 (YSZ) thin films have been formed at 800°C. Thermal decomposition mechanisms of dried Y–Zr–O were monitored by TG/DTA measurements in the dynamic 80%Ar+20%O2 atmosphere. The morphological features of obtained coatings were investigated by scanning electron microscopy (SEM). The electrical properties were characterized by impedance spectroscopy in a temperature range from 200°C to 450°C. Impedance results demonstrate that the conductivity of prepared layer is one order of magnitude lower in comparison with the YSZ bulk reference conductivity and the total conductivity of the YSZ film on silicon is mostly determined by the grain conductivity. [Copyright &y& Elsevier]

Abstract: Sol–gel processing is a powerful tool to prepare antireflective (AR) coatings on optical surfaces. In this paper the different strategies to obtain antireflective properties are reviewed: porous λ/4 layers, multilayer interference-type films and index-gradient materials such as “moth eye” structures. The processing of the respective films is described and evaluated; references to respective commercial products on glass substrates are given. AR coatings may have a particularly high importance for transparent ceramics as their index of refraction is significantly higher than that of common glass types. Reflective losses therefore are higher which is especially unpleasant for materials with a yet improvable intrinsic transparency. Recent studies indicate that specific porous λ/4 layers may exhibit pronounced anti-soiling features. Laboratory experiments as well as outdoor exposure tests were used to demonstrate the dust-repellant properties. [Copyright &y& Elsevier]

Abstract: Highly organized cubic mesoporous TiO2 and SnO2 nanocrystalline thin films were reproducibly synthesized via an evaporation-induced self-assembly (EISA) process with a triblock copolymer (Pluronic F127) as the template, by precisely controlling the water content and chelating agent in the initial sol solution as well as by controlling the external relative humidity during the aging step. It has been found that the mesoscopic regularity of the fabricated mesoporous films critically depends on the hydrolytic reactions of inorganic precursors. That is, suppressing the hydrolysis reaction in the initial sol and providing the long-term stability for the sol in the coated film during the aging step are key factors in the formation of highly organized structure. The synthetic strategy was also extended to obtain various TiO2- and SnO2-based mixed oxide thin films with tunable composition, including WO3/TiO2, SiO2/TiO2, Nb2O5/SnO2, by selectively controlling the kinetics of hydrolytic reaction for the additional inorganic precursors. The prepared composite films were crack-free, ultra-highly transparent, and thermally stable. [Copyright &y& Elsevier]

Ba0.8Sr0.2TiO3 (BST) thin films were prepared on Pt/Ti/SiO2/Si substrates by sol-gel processing. The BST thin films were patterned by wet chemical etching and the electrodes were shaped by lift-off technique. An improved etchant with the volume ratio of HF:HNO3:H2O2:H2O = 1:25:50:20 was developed for BST films etching. SEM graph shows that the unetched BST thin film is dense, crack-free and pore-free. EDS analyses indicate that Ba, Sr and Ti elements of etched areas are removed completely. XRD and AFM results show that the etchant-induced damage of the etched BST films could be partially recovered by post-annealing treatment. [ABSTRACT FROM AUTHOR]

Abstract: Developing an effective air purifier for indoor air quality (IAQ) purposes requires knowledge of the reaction rate of target compounds in the presence of other compounds that compete favorably with the target compounds for surface sites. To address this issue, the photocatalytic oxidation (PCO) of five C3 organic compounds on a sol-gel derived TiO2 thin-film catalyst was examined. Photocatalytic degradation of the five compounds was first compared in single component experiments at 50% relative humidity. The photocatalytic oxidation reaction rates proceeded in the following order: 1-propanol>propanal>propanone>propene>propane. The order of reaction rates was partially explained by considering the intermolecular forces of attraction that exist between the gas-phase molecules and the hydrated titania surface, with the lone exception of the ketone. A model that incorporates Henry''s law constant and hydroxyl radical reactivity was successful at predicting PCO reactivity. Relative photocatalytic degradation was also studied using multi-component experiments. Multi-component experiments with propanone+propene, propanal+propanone, and ethanol+propanone were conducted. In each case it was observed that compounds with stronger binding energy to the photocatalyst surface displaced compounds with weaker binding energies and inhibited their further reaction until the stronger binding species was oxidized to sufficiently low levels. Further investigation of relative binding energies of compounds of interest for PCO applications should be pursued in the future through combinations of experimental studies and theoretical molecular modeling techniques. [Copyright &y& Elsevier]

Ba(Sn0.15Ti0.85)O3 (BTS) thin films were deposited on Pt (111)/Ti/SiO2/Si substrates by sol-gel technique with a 30 nm thick BTS seed layer. The dielectric constant of the BTS films with and without seed layer was 720 and 395, respectively. The tunability of BTS thin films with seed layer was 52.1%, which was about two times larger than that of BTS thin films without seed layer at the frequency of 100 kHz with an applied electric field of 200 kV/cm. The results showed that the seed layer had an obviously effect on the orientation and dielectric properties of the BTS films. [ABSTRACT FROM AUTHOR]

Abstract: The pyrochlore Lanthanum Zirconium Oxide, La2Zr2O7 (LZO), has been developed as a potential replacement barrier layer in the standard RABiTS three-layer architecture of physical vapor deposited CeO2 cap/YSZ barrier/Y2O3 seed on Ni–5%W metal tape. The main focus of this research is to ascertain whether: (i) we can further improve the barrier properties of LZO; (ii) we can modify the LZO cation ratio and still achieve a high level of performance; and (iii) it is possible to reduce the number of buffer layers. We report a systematic investigation of the LZO film growth with varying compositions of La:Zr ratio in the La2O3–ZrO2 system. Using a metal–organic deposition (MOD) process, we have grown smooth, crack-free, epitaxial thin films of La x Zr1− x O y (x =0.2–0.6) on standard Y2O3 buffered Ni–5W substrates in short lengths. Detailed XRD studies indicate that a single epitaxial LZO phase with only (001) texture can be achieved in a broad compositional range of x =0.2–0.6 in La x Zr1− x O y . Both CeO2 cap layers and MOD–YBCO films were grown epitaxially on these modified LZO barriers. High critical currents per unit width, I c of 274–292A/cm at 77K and self-field were achieved for MOD–YBCO films grown on La x Zr1− x O y (x =0.4–0.6) films. These results indicate that LZO films can be grown with a broad compositional range and still support high performance YBCO coated conductors. In addition, epitaxial MOD La x Zr1− x O y (x =0.25) films were grown directly on biaxially textured Ni–3W substrates. About 3μm thick YBCO films grown on a single MOD–LZO buffered Ni–3W substrates using pulsed laser deposition show a critical current density, J c, of 0.55MA/cm2 (I c of 169A/cm) at 77K and 0.01T. This work holds promise for a route for producing simplified buffer architecture for RABiTS based YBCO coated conductors. [Copyright &y& Elsevier]

Co-effect of crystallization ambients (O2 and N2 mixed gas) and temperatures (600-800°C) on crystal structures and ferroelectric properties of the sol-gel deposited Bi3.25La0.75Ti3O12 (BLT) films is studied in this work. As the annealing temperature increases, the films get full crystallization and show different orientation. The film annealed in N2 at 650°C is a-axis oriented, and get large Pr but bad fatigue property, which is caused by the charged oxygen vacancies in the films annealed in the oxygen-deficient ambients. The film annealed in 20% O2 at 750°C is random oriented and exhibits excellent ferroelectric properties in terms of the largest Pr value of 11.5 μC/cm2 and the lowest Ec value of 83.3 kV/cm under a voltage of 12 V. Moreover, the film shows good fatigue endurance after 109 switching cycles. The crystllization and growth of the BLT films are sensitive to annealing ambients and temperatures. Therefore, the appropriate annealing ambient and temperature can improve the properties of the ferroelectric films greatly. [ABSTRACT FROM AUTHOR]

Abstract: Sol–gel thin film offers a number of advantages that makes it an attractive method for obtaining coatings on alloy. In this paper, an Al2O3 film was deposited on a γ-TiAl-based alloy from aluminum isopropoxide (Al(OC3H7)3) as precursor. The thin film synthesized using a dip-coating process, was uniform and crack-free. Isothermal and cyclic oxidations of the coated and uncoated specimens at 1000°C were performed to test its effect on the oxidation behavior of the alloy. The Al2O3 film exhibited beneficial effects on the oxidation resistance of the alloy. The oxidation rate of the Al2O3 coated specimens was much slower than that of the blank alloy. The oxide scales formed on the uncoated specimens were stratified. For the coated samples, beneath the Al2O3 film, a mixture layer of rutile TiO2 and α-Al2O3 occurred, but more α-Al2O3 formed on the coated specimens than that on the blank ones. The possible mechanism of the thin film on the oxidation behavior of the alloy was discussed. [Copyright &y& Elsevier]

Abstract: The overall purpose of this research is to develop a potentially low-cost, high throughput, high yield, manufacturing process for buffer deposition, and to gain a fundamental understanding of buffer layers required for an all metal-organic deposition (MOD) based chemical solution approach. This understanding is critical to the development of a reliable, robust, low-cost, long-length manufacturing process of 2G wires. The standard RABiTS architectures consists of a starting template of biaxially textured Ni–W (5at.%) substrate with a seed layer of Y2O3, a barrier layer of YSZ, and a CeO2 cap. In this three-layer architecture, all the buffers are deposited using reactive sputtering. We have recently demonstrated that the barrier properties and the performance of MOD La2Zr2O7 (LZO) match that of sputtered YSZ layers. In this work, the texture of MOD LZO was also improved by inserting a sputtered Y2O3 seed layer on which LZO grows without any degradation of texture. Significant improvement in the texture of sputtered Y2O3 seeds on NiW substrates is usually observed which is then transferred to the LZO layer. A key challenge for an all-solution approach is to replace the sputtered seed layer with a possible MOD seed layer with improved texture and on which no degradation of LZO texture occurs. Very recently, we have grown MOD La3TaO7 (LTO) seeds directly on biaxially textured Ni–W (3at.%) with improved texture. In this study, we report a systematic investigation of the growth MOD LZO barrier layer on MOD LTO seeds. Preliminary results show that it is possible to grow MOD LZO with improved texture on MOD LTO seeds. This approach could be potentially used for future all MOD buffer/YBCO coated conductors. [Copyright &y& Elsevier]

Abstract: The electrochromic (EC) behavior, the microstructure, and the morphology of sol–gel deposited nickel oxide (NiO x ) coatings were investigated. The films were produced by spin and dip-coating techniques on indium tin oxide (ITO)/glass and Corning glass (2947) substrates. The coating solutions were prepared by reacting nickel(II) 2-ethylhexanoate as the precursor, and isopropanol as the solvent. NiO x was heat treated at 350°C for 1h. The surface morphology, crystal structure, and EC characteristics of the coatings were investigated by scanning electron microscopy (SEM), electron dispersive spectroscopy (EDS), atomic force spectroscopy (AFM), X-ray diffractometry (XRD), and cyclic voltammetry (CV). SEM and AFM images revealed that the surface morphology and surface characteristics of the spin- and dip-coated films on both types of substrate were different. XRD spectra revealed that both films were amorphous, either on ITO or Corning glass substrates. CV showed a reversible electrochemical insertion or extraction of the K+ ions, cycled in 1M KOH electrolyte, in both type of film. The crystal structure of the cycled films was found to be XRD amorphous. Spectroelectrochemistry demonstrated that dip-coated films were more stable up to 1000 coloration–bleaching cycles, whereas spin-coated films gradually degraded after 500 cycles. [Copyright &y& Elsevier]

Abstract: Nanocrystalline cobalt oxide thin films were fabricated by sol–gel processing method. The effect of cobalt salt amount in sol–gel mixture on film properties was investigated by means of Raman spectroscopy and atomic force microscopy. Micropatterns of these sol–gel mixtures were fabricated by spin coating followed by a lift-off method. It is generally known that sol–gel processed films are difficult to etch or remove by chemical and plasma techniques. In this novel process, cobalt oxide microstructures could be fabricated by transformation of pre-fabricated nanocrystalline cobalt oxide particles in a sol–gel process. Also, the growth of carbon nanotubes on fabricated cobalt oxide films was investigated. It was found that different size multiwall carbon nanotubes could be grown on the cobalt oxide films depending on the concentration of cobalt salt in sol–gel mixtures. [Copyright &y& Elsevier]

Silica and zirconium dioxide sol-gel thin films made with Yb0.80La0.15Tb0.05F3 or Yb 0.80La0.15Eu0.05F3 nanoparticles are reported. Bright blue (413 and 435 nm), green (545 nm), and red (585 and 625 nm) emissions are produced from Tb3+ ions through cooperative up-conversion of 980 nm light. Similarly, red (591 and 612 nm) emission is generated from Eu3+ ions. These up-convertors may find use in white light sources. The cooperative up-conversion of Yb3+-Tb3+ ions is more efficient than of Yb3+-Eu3+ ions because the efficiency of energy transfer from excited Yb3+ ions to a Tb 3+ ion (0.37) is more than two-times higher than of excited Yb3+ ions to a Eu3+ ion (0.15), as estimated from the lifetime of excited Yb3+ ion. The estimated quantum yields of both Tb3+ ion and Eu3+ ion emissions are on the order of 40%, and hence are not the cause of the difference in efficiency. This approach does not work for Sm3+, Pr3+ , and Dy3+. Incorporation of the respective Ln3+ ions in nanoparticles is crucial, as controls, in which the various Ln3+ ions are incorporated directly into the sol-gel, that do not show cooperative up-conversion [ABSTRACT FROM PUBLISHER]

In this paper, we propose and demonstrate the use of multilayered (laminated) waveguides for increasing the available gain spectrum of sol-gel amplifiers. Experimental investigations of the effects of phosphorus codoping on the amplifier spectral characteristics and fluorescence decay are also presented. We demonstrate that the shape of the erbium emission cross section, for aluminophosphosilicate amplifiers, has a minor dependence on the amount of phosphorus doping and that spectral benefits are only achieved for aluminosilicate amplifiers, albeit with low levels of erbium inversion. Laminated amplifiers, consisting of alternating layers of two compositions, are shown to display novel spectral characteristics that cannot be obtained by the use of single composition cores. Internal gain, which is demonstrated for this device, also suggests that erbium inversion can be maintained at relatively high levels. Experimental results are supported by numerical analysis, and a 20-nm bandwidth increase is observed for laminated amplifiers, with gain levels up to 1.4 dB/cm indicated, when processing conditions are optimized. [ABSTRACT FROM PUBLISHER]

Abstract: Amorphous SiO2 thin films were deposited on Ti6Al4V alloy by sol–gel processing. Isothermal and cyclic oxidation tests of the coated and uncoated specimens were performed at 700 and 800 °C. The SiO2 film exhibited beneficial effects on the oxidation resistance of the alloy. Titania scales formed on the uncoated specimens, and severe spallation and stratification of the scales were observed. The oxidation rates of the silica coated specimens were decreased significantly. The silica film shrunk to about a quarter in thickness, probably by mechanism of crystallization of silica and evaporation of the organic additments. The oxide scales formed on the coated specimens were multilayered. Beneath the silica film, formation of a thick rutile titania layer followed by a thin alumina layer occurred. Above the silica film, alumina plus minor titania layer formed. It is deduced therefore that the growth of the multilayered and mixed oxide scales was dominated by both outward diffusion of metal and inward diffusion of oxygen. [Copyright &y& Elsevier]

Abstract: A device of multiple nano-TiO2 layers was proposed and fabricated to prevent a dye/nano-TiO2 region from serious photo-degradation. In this device, the top of the dye/TiO2 region was designed to be coated using sol–gel nano-TiO2 thin films to shield UV irradiation from the photo-degradation effect. The sol–gel TiO2 was prepared in a low temperature (75°C) and verified as nano-sized particles and an anatase crystalline structure. Different devices of the multi-layer samples fabricated using different compositions of nano-TiO2 were produced and exposed for UV irradiation tests. Results show that the presence of the sol–gel TiO2 films coated on top of the dye/TiO2 region can significantly alleviate the dye photo-degradation under UV irradiation. This multi-layer device can effectively improve the photo-stability of the dye/TiO2 region in a UV-exposure environment. [Copyright &y& Elsevier]

Abstract: RABiTS based metal-organic deposition (MOD) buffer/YBa2Cu3O7−δ (YBCO) approach has been considered as one of the potential, low-cost approaches to fabricate high performance second generation coated conductors. The most commonly used RABiTS architectures consisting of a starting template of biaxially textured Ni–W (5 at.%) substrate with a seed layer of Y2O3, a barrier layer of YSZ, and a CeO2 cap. In this three layer architecture, all the buffers are deposited using physical vapor deposition (PVD) techniques. Using these PVD deposited templates, 0.8-μm thick MOD-YBCO films with an I c (critical current) of 250A/cm have been achieved routinely in short lengths. We have developed a low-cost, non-vacuum, MOD process to grow epitaxial buffer layers on textured Ni–5W substrates. The main challenge in this effort is to match the performance of MOD templates to that of PVD templates. We have recently shown that the properties of MOD-La2Zr2O7 (LZO) layers can be improved by inserting a thin Y2O3 seed layer. Using MOD-CeO2 cap layers, we have demonstrated the growth of high performance MOD-YBCO films with an I c of 200A/cm-width on MOD-La2Zr2O7/Y2O3/Ni–5W substrates. This approach could potentially decrease the overall cost of the coated conductor fabrication. [Copyright &y& Elsevier]

Abstract: A new acrylate-modified silica incorporating tantalum is synthesised via a sol–gel route. After deposition, the few micron-thick films can be photo-polymerised by UV-irradiation. FTIR spectroscopy gives a first insight into the curing process and the chemical structure of the hybrid material. The refractive index of the layers can be modulated by varying the concentration of tantalum in the material. Coatings exhibit a good transparency in the blue range of the optical spectrum. Finally, the propagation losses are low enough to make the material suitable for applications in integrated optics. [Copyright &y& Elsevier]

Abstract: Transparent thin films of nanocrystalline anatase were obtained by dip-coating process using an ethanolic suspension of redispersed nanoparticles. This suspension was prepared by sol–gel route and their redispersability achieved by surface grafting of para-toluene–sulfonic acid and acetylacetone. The effects of the acetylacetone content on the powder redispersibility and on the structural evolution of films were determined by small angle X-ray scattering, X-ray reflectometry and X-ray diffraction for different firing temperatures. The results demonstrated that the porous structure of the studied films consist of agglomerates of primary particles with two levels of porosity. The control of the amount of capping ligand allows for a fine-tuning of the average pore size of the dried films. Upon increasing the firing temperature up to 500°C, progressive increase in apparent density, average pore size of films and average crystallite size of powders were observed. [Copyright &y& Elsevier]

Abstract: Dense films of CeO2 have been epitaxially grown on bi-axially textured Ni tape from a spray MOD technique. Ce-2-ethylhexanoate in toluene solution has been used as a precursor. This carboxylic precursor is ultrasonically sprayed in a specially designed machine allowing the tape to be covered to move. After drying, the film is converted to the oxide above 600°C in reducing atmosphere, avoiding oxidation of the Ni substrate. The ceramic film is densified at 900°C (grain size 90nm) and it grows epitaxially on the substrate. The thickness of the film is determined from IR reflectivity to be 87nm in agreement with SEM. This continuous process could be easily scaled up. [Copyright &y& Elsevier]

Tellurite thin films have potential to be applied in optical and electronic areas, but it is difficult to prepare from tellurium(IV) alkoxides by sol–gel processing due to the instability of tellurium(IV) alkoxides and their derivatives. The precursor of tellurium(VI) complex is synthesized and applied to make tellurium oxide thin films without addition of any modifiers in the study. The decomposition process of the complex is investigated, and the thin films derived from this precursor are characterized structurally, morphologically and optically. [Copyright &y& Elsevier]

Pb(Zr,Ti)O3 (PZT 30/70) and Mn-doped Pb(Zr,Ti)O3 (PMZT 30/70) thin films have been fabricated on Pt/Ti/SiO2/Si substrates by a chemical solution deposition technique. The experiments found that the addition of Mn in PZT thin films greatly improves the ferroelectric properties of thin films. It is demonstrated that the Mn-doped (1 mol%) PZT showed fatigue-free characteristics at least up to 1010 switching bipolar pulse cycles under 10 V and excellent retention properties. The Mn-doped PZT thin films also exhibited well-defined hysteresis loops with a remnant polarization (Pr) of 34 μC/cm2 and a coercive field (Ec) of 100 kV/cm for the thickness of 300 nm. Dielectric constant and loss (tanδ) for Mn doped PZT thin films are 214 and 0.008, respectively. These figures compare well with or exceed the values reported previously. In this paper, the mechanism by which Mn influences on the ferroelectric properties of PZT thin films has also been discussed. [Copyright &y& Elsevier]

Sensitive and versatile evanescent wave-sensing systems featuring polished optical fiber-based sensor designs with low-cost light sources have been developed for temperature, relative humidity, and pH measurements. The work herein contained describes the fabrication of three types of sensors based on standard silica, single-mode fibers previously subjected to a lateral polishing of the cladding. Temperature sensing through oils whose refractive index varied linearly with temperature showed applicability with up to 5 dB/°C for a 5° range. Polyvinyl alcohol films on the fibers showed almost 10-dB linear variation from 70% to 90% relative humidity. Sol-gel trapped dyes as thin films on the polished surface were capable of performing 15-dB output variation (although not linearly) for pH ranging from 2 to 11. [ABSTRACT FROM PUBLISHER]

Bi4−xLaxTi3.0O12 (BLT, x=0.67–0.70) ferroelectric thin films were prepared on a single crystalline aluminum oxide film onto Si substrate (c-Al2O3/Si), and amorphous phase aluminum oxide film onto Si substrates (a-Al2O3/Si) by the sol–gel method. In order for crystallization, the as-coated films were annealed at the temperature of 650 and 700 °C for 30 min. The crystalline quality, surface morphologies and electrical properties were affected by the substrate types as well as the annealing temperature. The BLT films annealed at above 650 °C exhibited typical bismuth layered perovskite structures with (00l) preferred orientation. From X-ray diffraction analyses, the BLT films coated on c-Al2O3/Si substrate were higher in reflection peaks and smaller in full width at half maximum (FWHM) values compared with the ones coated on a-Al2O3/Si substrate. The Rrms value of the film annealed at 700 °C on c-Al2O3/Si substrates was three times smaller than that of the film coated on a-Al2O3/Si substrate, showing a rather smooth surface when it was coated on c-Al2O3/Si substrate. The memory window voltage of the BLT film coated on c-Al2O3/Si substrate was 2.5 V, which is about twice compared with the one coated on a-Al2O3/Si substrate. The leakage current of BLT film annealed at 650 °C was approximately 1×10−7 A/cm2 at the applied voltage of 3 V for both samples. [Copyright &y& Elsevier]

The precursor containing peroxotungstic acid (PTA) was prepared by the reaction of tungstic acid with H2O2 (30%) solution in water–ethanol mixture. This was utilized for the deposition of WO3·nH2O film on conducting (F-doped SnO2 coated) flat glass substrate by the dipping technique. The films were cured in the temperature range of 200–300 °C in air. The optimum thickness of the film (300–500 nm) was obtained by successive operations (3–5 numbers). Films of around 500 nm thickness exhibited 60–70% transmission in the visible region. Electrochromic properties (colouration↔bleaching) of the films were studied by cyclic voltammetry (CV) using a classical three-electrode potentiostatic cell system. The cell system consists of a WO3-coated sample as working electrode, a platinum rod as counter electrode, Ag/AgCl as reference electrode and 0.5 M LiClO4 in propylene carbonate as an electrolyte. Several voltammograms were recorded within the voltage range of +1.5 to −1.8 V with a scan rate of 50 mV/s. A continuous curve was observed for the films at a certain voltage sweep where a random insertion of Li+ occurred reversibly in a definite crystallographic site [WO3 (colourless)+nLi++ne−↔ LinWO3 (blue)]. A dark blue colouration (%T=20–30% in the visible region) was observed under a constant voltage of −1.8 V whereas bleaching occurred at +1.0 V (%T=60–70%), which was studied simultaneously along with the voltage sweep of CV. The colouration time (Tcol) and the bleaching time (Tbl) were almost equal as revealed by the simultaneous study of the second signal (photomultiplier output coupled with the electrochemistry system) during colouration↔bleaching. Coatings of about 500 nm thickness exhibited more that 500 cycles (colouration↔bleaching). The reversibility of the cycle remained good but the intensity of the colouration decreased with the number of cycles. This was possibly due to the structural deformation of WO3 films for its long time exposure to the electrolytic solution. The cathodic current (Ic) and anodic current (Ia) increased with increasing thickness. [Copyright &y& Elsevier]

UV irradiation of sol–gel derived HfO2 thin films in N2O using excimer lamps was found to effectively remove OH groups, dissociate unreacted Hf–OH and further oxidize sol–gel layers, forming HfO2 thin films with a high stoichiometry of 1.97. No interface oxidation and silicate formation has been observed when irradiated at 400 °C for 20 min while the films retain a desired amorphous structure. UV-irradiated sol–gel layers exhibited significantly improved optical properties, with high optical transmittances of 81–97% in the visible region of the spectrum, a high refractive index of up to 1.90 being achieved. A leakage current density as low as 5.8×10−6 A cm−2 at 1 MV cm−2 and breakdown field of larger than 5 cm−2 were obtained on these sol–gel layers with radiation for 20 min. [Copyright &y& Elsevier]

Ferroelectric thin films of (Pb 0.76 Ca 0.24 )TiO 3 nominal composition have been obtained, by multiple spin-on deposition on Si-based substrates and RTP crystallization, from precursor solutions processed by the diol-based sol-gel method. A mixed <001>/<100> or <111> preferential orientations were promoted by appropriate choice of the substrate, as determined by XRD measurements. The effect of substrate annealing and crystallized film annealing on the pyroelectric coefficient of the films was determined and discussed. Poling of the films at room temperature and at 150 °C was tested. The highest pyroelectric coefficient achieved was γ ∼ 40.0 × 10 -9 Ccm -2 K -1 . [ABSTRACT FROM AUTHOR]

Sol–gel processing has been used to prepare optically transparent thin films in the system TeO2–TiO2. The structure and morphology of the thin films were investigated by X-ray diffraction (XRD) and field emission microscopy (FEM). The calculated refractive index, band gap and Urbach energy values for the thin films are consistent with the values obtained in other studies of conventionally melted tellurite and multicomponent tellurite glasses. The results show that the thin films by sol–gel processing offers an attractive route for the fabrication of such materials into devices. [Copyright &y& Elsevier]

Thin film of a lithium ionic conductor, LiTi2(PO4)3 (LTP), was prepared by sol–gel method from an alkoxide solution. Heating temperature of the spin-coated film between 600 and 800 °C resulted in single-phase LTP films. The film heated at 800 °C showed a reticulation texture with a thickness of 300 nm. It showed a high lithium ionic conductivity 4.4×10−6 S/cm, although it has a large porosity due to the texture. High sintering capability of the sol–gel film was regarded to reduce a grain boundary resistance in LTP substance, resulting in the high conductivity. [Copyright &y& Elsevier]

Polycrystalline BaTiO3/SrTiO3 multilayered thin films have been prepared on Pt/Ti/SiO2/Si substrates by a sol–gel processing. The X-ray diffraction (XRD) patterns and Auger electron spectroscopy (AES) indicate that the multilayered thin films were formed. The dielectric constant of the multilayered films was significantly enhanced and the dielectric loss was almost the same as that of the uniform BaTiO3 and SrTiO3 thin films. A dielectric constant of 660 at 1 kHz was observed for a stacking periodicity of 66 nm at room temperature and the corresponding dielectric loss was maintained below 0.05. The study indicates that there are some differences between the multilayered films and the uniform films in the dielectric constant–frequency relation and capacitance–voltage characteristics. The report also analyzes the mechanism of dielectric enhancement of the multilayered thin films prepared by the sol–gel process. [Copyright &y& Elsevier]

In this work an UV assisted Sol–Gel process has been successfully developed for preparation of thin films of Ce1−xGdxO2−0.5x (CGO) on dense and porous substrates, is reported. Crystallisation behaviour, chemical composition and microstructure of the CGO films were investigated using X-ray diffraction, EDX and scanning electron microscopy. The effects of deposition parameters on the thin film growth have also been investigated using three dense substrates, Si (100), stainless steel and Quartz. However, it is required to modify the surface of the porous substrate (porous CGO) in order to prevent the sol–gel precursor from infiltrating into the pores due to capillary force. It is also important to prevent thin films from cracking and forming a particle structure due to surface roughness. The application of mutillayer by UV-radiation assisted sol–gel method has deposited uniform, non-porous CGO thin films on porous substrates and has effectively overcome the problems. [Copyright &y& Elsevier]

Ferroelectric Pb(Zr0.52 Ti0.48)O3 thin films were prepared by sol-gel processing on the Pt/Ti/SiO2/Si(100) substrates. Effects of the concentration (0.2–0.8 M) of the starting solution (Pb/Zr/Ti= 1.1/0.52/0.48) and the sintering temperature (500–700 ‡C) on crystallinity, microstructure and electrical properties of PZT thin films were investigated. For the thin film prepared at 0.4 M starting solution, the highest crystallinity appeared at a sintering temperature of 650 ‡C. The average grain size of the PZT thin films was about 0.17 Μm. The film thickness was about 0.2 Μm. The relative dielectric constant and the dissipation factor of the film measured at 1 kHz were about 750 and 4.3%, respectively. The remnant polarization (Pr) and coercive field (Ec) of the film measured at the applied voltage of 5 V were about 49 ΜC/cm2 and 134 kV/cm, respectively. [ABSTRACT FROM AUTHOR]