Aqueous Spray Solution Research Articles

Selective deposition of p-type Cu2O or conductive Cu thin film at 180∘C in air on a quartz glass substrate: Development of an aqueous spray solution using two-compartment electrolysis system

A conductive Cu thin film with a thickness of 170[Formula: see text]nm, electrical resistivity of 8.9(2) [Formula: see text][Formula: see text]cm and adhesion strength of 12(7) MPa was fabricated at 180∘C in air. The spray solutions were prepared by electrolyzing Cu electrodes in an aqueous solution of ammonium formate, and then by adding ethylenediamine-N, N, N[Formula: see text], N[Formula: see text]-tetraacetic acid (EDTA). The surface morphology image of resultant Cu thin film, observed by a field emission scanning electron microscope, revealed Cu grains with particle sizes of ca. [Formula: see text][Formula: see text]nm. It was indicated that the Cu complex containing EDTA ligand in the spray solution plays important roles to (1) provide enough amount of carbon atoms as a reducing agent for phase transition of its coordinated Cu[Formula: see text] to crystalline Cu0 and (2) prevent the product from oxidation under atmospheric O2 during spray coating.

Electrochemical properties of WO3-reduced graphene oxide composite powders prepared by one-pot spray pyrolysis process

In this work, we report the preparation of WO3-reduced graphene oxide (rGO) composite powders by spray pyrolysis process using a stable graphene oxide colloidal solution with ammonium tungstate. The ultrafine WO3 nanocrystals below 10 nm in size are dispersed within the rGO matrix. The bare WO3 powders prepared from the aqueous spray solution of ammonium tungstate are spherical and do not aggregate. The bare WO3 and WO3-rGO composite powders show monoclinic and cubic crystal structures, respectively. The initial discharge capacities of the bare WO3 and WO3-rGO composite powders at a current density of 100 mA g−1 are 771 and 941 mA h g−1, respectively, and their initial Coulombic efficiencies are 67 and 65%, respectively. The discharge capacities of the bare WO3 and WO3-rGO composite powders at the 300th cycle are 282 and 546 mA h g−1, respectively.

The effect of tartaric acid in the deposition of Sb2S3 films by chemical spray pyrolysis

Sb2S3 films grown by chemical bath deposition have been used as an absorber in extremely thin inorganic absorber solar cells. In the present work, Sb2S3 thin films were deposited by chemical spray pyrolysis. The aqueous spray solution consisted of SbCl3 (Sb=2mmol/L), thiourea (S) and tartaric acid (TA) in molar ratios of Sb:S:TA=1:3:10 or 1:3:1, and the solution was nebulized onto preheated soda-lime glass substrates. The deposition temperature ranged from 205°C to 230°C and 205°C to 355°C for Sb:S:TA=1:3:10 and 1:3:1, respectively. The effect of the tartaric acid concentration in spray solution, deposition temperature and the annealing temperature on the film properties was studied with X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy and Fourier transform infrared spectroscopy (FTIR), thermogravimetric and differential thermal analysis (TG/DTA) of tartaric acid was carried out.The films deposited from solutions with Sb:S:TA ratio of 1:3:10 at 205°C are ca. 1µm thick, contain orthorhombic stibnite (Sb2S3) phase and high amount of carbon and oxygen residues. The reduced TA concentration (1:3:1) in the spray solution leads to orthorhombic Sb2S3 films with decreased content of carbon and oxygen in the films compared to solutions with Sb:S:TA=1:3:10. An increase in the deposition temperature from 205°C to 355°C decreases the mean crystallite size from 25nm to 15nm and a decrease in sulfur and an increase in oxygen content was detected. SEM images indicate that the morphology and the thickness of the films grown with Sb:S:TA ratio of 1:3:1 are not homogeneous and an increase in deposition temperature results in thinner films. FTIR spectra of Sb2S3 film substance confirm that the TA has not completely decomposed at the used deposition temperatures. According to the thermal analysis study, TA decomposition takes place in three steps where 95% of mass is lost by 254°C and the TA is completely decomposed only at 495°C. Additionally, we report the first results on growing Sb2S3 films with band gap of 1.7eV by chemical spray pyrolysis using alcohol solutions.

Tin sulfide (SnS) nanostructured films deposited by continuous spray pyrolysis (CoSP) technique for dye-sensitized solar cells applications

Tin sulfide (SnS) nanostructured films have been deposited on transparent conducting glass substrate using continuous spray pyrolysis (CoSP) technique using aqueous spray solution of tin chloride and thiourea. Structural, morphological and optical properties of as-synthesized SnS nanostructured films showed the formation of (101) oriented orthorhombic SnS with nanoflakes having a direct band gap of 1.40eV. X-ray photoelectron spectroscopy (XPS) analysis confirms the formation of pure SnS with Sn in +2 oxidation state. The SnS nanostructured film has also been characterized using Brunauer–Emmett–Teller (BET) technique to determine the surface area and pore volume which are found to be 11.4m2/g and 0.02cm2/g, respectively. The film has been used as a counter electrode (CE) in a triiodide/iodide (I3−/I−) based dye-sensitized solar cells (DSSCs). The DSSCs of 0.25cm2 area with SnS nanostructured CE exhibits a lower power conversion efficiency (2.0±0.06%) than that for the cell with standard platinum (Pt) CE (4.5±0.13%). However, the usefulness of the CoSP technique for deposition of nanostructures SnS CE film has been established in the present study.

Electrochemical properties of yolk–shell and hollow CoMn2O4 powders directly prepared by continuous spray pyrolysis as negative electrode materials for lithium ion batteries

Yolk–shell and hollow CoMn2O4 powders are prepared directly by spray pyrolysis from aqueous spray solutions with different concentrations of sucrose. Phase pure tetragonal CoMn2O4 powders without impurity phases are prepared even without post-treatment. The powders prepared from a spray solution with a low sucrose concentration of 0.1 M have a hollow structure. The single and double-shelled yolk–shell powders prepared from spray solutions with 0.4 and 0.7 M sucrose, respectively, have high discharge capacities of 519 and 573 mAh g−1 in the voltage range of 0.01–3 V, respectively, after 40 cycles at a high discharge rate of 800 mA g−1. However, the thick- and thin-shelled hollow powders prepared from spray solutions without and with 0.1 M sucrose have low discharge capacities of 418 and 276 mAh g−1 after 40 cycles, respectively. The discharge capacities of the yolk–shell powders are as high as 579, 530, and 443 mAh g−1 at discharge rates of 1600, 2400, and 3200 mA g−1 after 40 cycles, respectively.

Nanosized LiMn2O4 powders prepared by flame spray pyrolysis from aqueous solution

LiMn2O4 powders have been directly prepared by flame spray pyrolysis from an aqueous spray solution of the metal salts. The powders prepared at a low fuel gas flow rate (3Lmin−1) comprise particles with a bimodal size distribution, i.e., submicron- and nanometer-sized particles, and have crystal structures of LiMn2O4 and Mn3O4 phases. However, the powders prepared at a high fuel gas flow rate (5Lmin−1) comprise nanometer-sized particles and have pure crystal structure of LiMn2O4 phase. The powders comprising nanosized particles are well crystallized, and the particles have a polyhedral structure. The mean particle size of these powders is 27nm. The powders prepared directly by flame spray pyrolysis comprise nanosized particles and have the pure crystal structure of LiMn2O4, irrespective of the amount of excess lithium in the precursor solution. The initial discharge capacities of these powders increase from 91 to 112mAhg−1 when the amount of excess lithium is increased from 0% to 30% of the stoichiometric amount. The optimum amount of excess lithium required to prepare LiMn2O4 powders with nanosized particles and the maximum possible initial discharge capacity is 10%.

The Role of Carbon Black in the Preparation of GdPO4:Tb Phosphor Powders by Spray Pyrolysis

Nano-sized carbon black was applied in the spray pyrolysis as the nucleation seeds. Green-emitting Gd0.81Tb0.19PO4 phosphor powders were prepared by spray pyrolysis from the colloidal spray solution with nano-sized carbon black. The Gd0.81Tb0.19PO4 phosphor powders prepared from the colloidal spray solution had regular morphology and filled structure. The mean size and geometric standard deviation of the phosphor powders prepared from the colloidal spray solution were 0.95 µm and 1.5. The Gd0.81Tb0.19PO4 phosphor powders prepared from the colloidal spray solutions had similar photoluminescence intensities to that of the phosphor powders prepared from the aqueous spray solution under vacuum ultraviolet. Carbon black did not act as impurity of the Gd0.81Tb0.19PO4 phosphor powders.

Design of porous microparticles with single-micron size by novel spray freeze-drying technique using four-fluid nozzle

Spray freeze-drying (SFD) process, which is a novel particle design technique previously developed by authors, has been improved by using four-fluid nozzle (4N) instead of conventional two-fluid nozzle (2N) to expand its application in pharmaceutical industry. Aqueous spray solutions of the drug and the polymeric carrier were separately supplied into 4N, and atomized while colliding with each other at the tip of nozzle. The droplets of mixed solutions were directly immersed into liquid nitrogen and immediately frozen to form a suspension. Then, the iced droplets were lyophilized by freeze-dryer to prepare the composite particles of the drug and carrier. This process has been used in the present study to modify and enhance the dissolution profiles of poorly water-soluble drug, phenytoin. Water-soluble and enteric polymeric carriers in pharmaceutical use were used as a dissolution modifier. The SFD composite particles prepared by using 4N were fully characterized compared to those using 2N from morphological and physicochemical perspectives. It was found that the particles have fine porous structure producing vast specific surface area. Further, phenytoin was completely dispersed as amorphous state in the polymeric matrix with higher carrier ratio than phenytoin:carrier = 1:3. The dissolution of phenytoin from the water-soluble carrier-based particles was greatly enhanced because of large effective surface area and disappearance of crystalline. On the other hand, the release profiles from enteric carrier-based particles showed the typical enteric patterns, that is, delayed in acidic medium and accelerated in neutral pH. The results demonstrated that SFD technique using 4N has potential to develop the novel solubilized formulation for poorly water-soluble APIs.

Nano-sized α and β-TCP powders prepared by high temperature flame spray pyrolysis

Nano-sized α-TCP powders with spherical shape and non-aggregation characteristics were directly prepared by high temperature flame spray pyrolysis from the mixed spray solution of water and ethyl alcohol. The α-TCP powders prepared from the aqueous spray solution without ethyl alcohol had a bimodal size distribution with nanometer and micron sizes. Nano-sized and monodisperse α-TCP powders were prepared when the volume ratio (ethyl alcohol/distilled water, V/V) in the mixed solvent was of 40/60. The mean size of the nano-sized α-TCP powders was 32 nm. The composition ratio of calcium and phosphorous components of the nano-sized α-TCP powders was 1.49. The mean size of the spherical-like powders post-treated at a temperature of 600 °C was 57 nm. The mean size of the powders increased with increasing the post-treatment temperatures. The phase of α-TCP powders prepared by flame spray pyrolysis did not change at post-treatment temperatures below 700 °C. On the other hand, the powders post-treated at temperatures of 800 and 900 °C had single β phase of TCP.

Gd 2O 3:Eu phosphor powders prepared using a size-controllable droplet generator

Gd 2O 3:Eu phosphor powders were prepared by a filter expansion aerosol generator (FEAG) process capable of changing the mean size of droplets. The change in the mean size of the Gd 2O 3:Eu phosphor powders according to the concentrations of polyethylene glycol added to spray solutions was caused by the difference in the mean size of the droplets produced via the FEAG process. The mean sizes of droplets produced by the FEAG process were affected by the surface tension and viscosity of the spray solutions. The mean sizes of the Gd 2O 3:Eu phosphor powders obtained from the spray solutions with the same concentration of metal salts changed from 1.5 to 4.2 μm according to the concentrations of polyethylene glycol and citric acid added to the spray solutions. The maximum photoluminescent intensity of the phosphor powders obtained from the spray solutions with polymeric precursors and boric acid flux was 144% of that of the phosphor powders obtained from the aqueous spray solutions without flux.

GdPO4:Tb phosphor particles prepared by spray pyrolysis from the polymeric spray solution

Fine-sized Gd0.81Tb0.19PO4 phosphor particles with spherical shape, dense inner structure and narrow size distribution were prepared by spray pyrolysis. The morphologies and size distribution of the particles prepared by spray pyrolysis were affected by the types of spray solution. The Gd0.81Tb0.19PO4 phosphor particles obtained from the aqueous spray solution had hollow inner structure and bimodal size distribution. However, the Gd0.81Tb0.19PO4 phosphor particles obtained from the polymeric spray solutions with citric acid and polyethylene glycol had dense inner structure and narrow size distribution. The mean size of the particles obtained from the aqueous spray solution was 1.3 μm. On the other hand, the mean size of the particles obtained from the polymeric spray solution with citric acid and polyethylene glycol was 0.8 μm. The Gd0.81Tb0.19PO4 phosphor particles obtained from the polymeric spray solution with citric acid and polyethylene glycol (PEG 400) had higher photoluminescence intensity under vacuum ultraviolet light than that of the phosphor particles obtained from the aqueous spray solution.

LiFePO 4/C cathode powders prepared by spray pyrolysis from the colloidal spray solution containing nano-sized carbon black

Carbon-mixed LiFePO 4 cathode powders were prepared by spray pyrolysis from a colloidal spray solution. The nano-sized carbon black added into the spray solution as its colloidal seed material affected the morphologies, mean sizes, and electrochemical properties of the LiFePO 4 cathode powders. The precursor powders obtained from the aqueous spray solution without carbon black were large and had broad size distributions. On the other hand, the precursor powders obtained from the colloidal spray solution with carbon black were fine and had narrow size distributions. The initial discharge capacity of the LiFePO 4 cathode powders obtained from the aqueous spray solution was 94 mAh g −1; it rose to 120 mAh g −1 when 5 wt.% carbon black was added into the spray solution, and then to 136 mAh g −1 when the amount of carbon black added into the solution was increased to 10 wt.% of the LiFePO 4 powders. The addition of carbon black into the spray solution improved the cycle performance of the LiFePO 4 powders.

ZnO thin films on aluminized steel by spray pyrolysis

AbstractSpray pyrolysis is a low‐cost technique and results in minimal waste production when using adequate precursors. The process allows the coating of large surfaces and is appropriate for adaptation into an industrial production line. The aim of this work has been to obtain, by spray pyrolysis, thin and compact ZnO films on 30 × 40 cm galvanized steel sheets heated by high frequency magnetic induction and using zinc acetate precursor in aqueous spray solution. The work includes a study of optimized deposition conditions (substrate temperature, precursor solution concentration, flow rate and spray time) controlled ex situ by SEM, XPS, XRD and UV‐Vis‐NIR and FTIR diffuse reflectance spectroscopy, in order to obtain an effective barrier coating with low thermal emittance when the steel is used as a base material for solar thermal devices. Our results show improved anti‐corrosion performance when the substrate coverage is guaranteed, substrate temperature and deposition time being the main factors to accomplish the optical requirements of the ZnO‐coated galvanized steel. Copyright © 2006 John Wiley & Sons, Ltd.

Compositional, structural and electrical characterization of barium titanate thin films prepared on fused silica and Si(111) by spray pyrolysis

Barium titanate thin films have been prepared by chemical spray pyrolysis. Aqueous spray solutions of titanium isopropoxide and barium acetate, equimolar with respect to titanium and barium, were used as precursors. Deposition was carried out at a substrate temperature of 250°C. As-deposited films are amorphous. Films of BaTiO 3 (perovskite) were obtained by calcination in air to 600°C for various hours. Perovskite films are compact and smooth, according to their morphological aspect studied by scanning electron microscopy (SEM). X-ray photoelectron spectroscopy (XPS) combined with 4 keV Ar + depth profiling has shown that the as-deposited film corresponds to BaTiO 3 and that its composition stays constant through the whole film thickness. Residual carbon (in the form of BaCO 3 ) coming from the organic precursor solutions is only detected at the surface of the film, limited to the first atomic monolayers as revealed by depth profiling. Calcination in air at 600°C decreases this amount but BaCO 3 is still present at a percentage of 25% with respect to the whole amount of Ba in the film surface. Electrical characterization of a calcined BaTiO 3 film deposited on conductive n-type Si(111) was carried out with impedance spectroscopy in a frequency range of 10 Hz to 1 MHz. Assuming a film thickness of 100 nm as deduced by XPS depth profiling, the relative dielectric permittivity of our films can be estimated to be 80 at a frequency of 1 kHz.

Suppression of agglomeration in fluidized bed coating I. Suppression of agglomeration by adding NaCl

Fluidized bed coating was carried out with aqueous spray solution at various additional amounts of NaCl, using water-soluble hydroxypropyl cellulose (HPC) or hydroxypropylmethyl cellulose (HPMC) as membrane material, and spherical granules made of crystalline cellulose (Celphere™) as core particle. The mean particle diameter, density and surface morphology of the coated particles were studied. The viscosity of the spray solution was studied with a corn-plate viscometer at various additional amounts of NaCl, temperatures and concentrations of the spray solution. Agglomeration of particles was clearly suppressed by adding NaCl to the aqueous spray solution in both cases of HPC and HPMC. The mean particle diameter of the coated particles decreased with the increasing additional amount of NaCl in the spray solution. The viscosity of HPC water solution began to decrease at over 6% (w/v) NaCl concentration at 30°C. The NaCl concentration required to reduce the viscosity of the HPC solution became lower as temperature became higher. When the viscosity of the solution decreased, turbidity and/or precipitate were observed. These results suggest that the suppression of agglomeration was caused by the reduction in the viscosity of the spray solution through salting-out of the polymeric membrane materials.

A Study of the Absorption of CH3I by Aqueous Spray Solutions

A Study of the Absorption of CH₃I by Aqueous Spray Solutions

The Response of Kidney-Bean and Soybean Plants to Aqueous-Spray Applications of 2,4-Dichlorophenoxyacetic Acid With and Without Carbowax

1. Soybean plants differ from kidney-bean plants in their response to aqueous-spray applications of 2,4-dichlorophenoxyacetic acid containing Carbowax. 2. The addition of any of three Carbowaxes to aqueous-spray solutions of 2,4-dichlorophenoxyacetic acid enhanced its activity in inhibiting growth of kidney-bean plants but did not aid in inducing inhibitory responses in soybean plants. 3. Because of its solubility properties, the ammonium salt of 2,4-dichlorophenoxyacetic acid is suggested instead of the acid form for use in general herbicidal sprays.