Pneumatic Spray Research Articles

Characterization of ZnO thin films obtained by ultrasonic spray pyrolysis for application in UV photoconductive detectors

This paper presents the structural, optical and electrical characterization of ZnO thin films obtained by ultrasonic spray pyrolysis (USP). Based on these characterizations, the deposition conditions that provide films with higher crystallinity and greater absorption were determined. The resistivity of the films was reduced by annealing in nitrogen environment and was measured with a 4-point probe. The annealed films were characterized by AFM, SEM and XPS. Two photoconductive detectors were fabricated, with high and low resistivity films, and the responsivity was obtained for both. The two detectors showed a high UV response, but the photodetector developed from the annealed film demonstrated a maximum responsivity of 3000 A W−1 at 369 nm with a 2 V bias voltage. This result is higher than results obtained with low-cost techniques such as sol-gel, pneumatic spray pyrolysis, and even some results reported by sputtering.

Ni-Doped ZnO Thin Films Deposited by Pneumatic Spray Pyrolysis

The objective of the present work is the study the Ni concentration effect on the optical, structural and electrical properties of ZnO:Ni thin films deposited by pneumatic spray pyrolysis method. Un-doped and Ni-doped ZnO thin films were prepared from zinc acetate dihydrate and nickel chloride hexahydrate dissolved in distilled water onto glass substrates by pneumatic spray pyrolysis method. Solution concentration, substrate temperature and nozzle-substrate distance were kept constant during all deposition processes. Effect of nickel content on the optical, structural and electrical properties of as-prepared films obtained was investigated by UV–Vis-NIR spectrophotometry, X-ray diffraction and four-point probe technique. The results indicate that the deposited films are well adherent to the substrates, present surface roughness and have a preferential growth in the (002) direction. The observed transmittance in the visible region was situated between 60% and 70%. For Ni-doped ZnO, there are two separate phases. The Urbach energy, grain size, and electrical conductivity increase with Ni content. The same behavior for both the optical energy gap and the ZnO:Ni lattice parameters.

The role of SnO2 high resistivity transparent layer deposited onto commercial conducting glass as front contact in superstrate configuration thin films solar cells technology: influence of the deposition technique

The deposition of a high resistivity transparent (HRT) oxide between a transparent conductive oxide (TCO) and the window CdS has demonstrated the improvement of performance of CdS/CdTe solar cells, fabricated in the superstrate-configuration. In this work the influence of the pneumatic spray pyrolysis (PSP) and magnetron sputtering techniques on the properties TCO/SnO2/CdS structure through the deposition of the intermediate SnO2 between the commercial conducting glass and CdS window is presented by means of X-ray photoelectron spectroscopy (XPS), secondary ion mass spectroscopy (SIMS), and contact resistance, calculated using transmission line method (TLM), in order to reduce the front contact resistance in devices with superstrate-configuration. The results of this work are applicable to other solar cells in the same configuration as the recent solar cells based on the compound Sb2Se3, where the use of this type of HRT has not been studied.

Quantum Efficiency Enhancement Depending on the Thickness of p-GaN Spacer Layer in Localized Surface Plasmon-Enhanced Near-Ultraviolet Light-Emitting Diodes by Using Colloidal Silver Nanoparticles

We demonstrated the dependence on thickness of p-GaN spacer layer in the localized surface plasmons (LSPs)-enhanced near-ultraviolet light-emitting diodes (NUV-LEDs) by pneumatic spray process using colloidal silver (Ag) nanoparticles (NPs). The LSPs-enhanced NUV-LEDs with 10- and 20-nm-thick p-GaN spacer layer showed enhanced internal quantum efficiency (IQE) and reduced effective exciton lifetime by introducing the colloidal Ag NPs. The IQE of LSPs-enhanced NUV-LEDs with 10- and 20-nm-thick p-GaN spacer layer was increased by 18.8% and 24.2%, respectively. These results indicate that the spontaneous emission rate is increased by LSPs-excitons resonant coupling. However, the NUV-LEDs with 40- and 100-nm-thick p-GaN spacer layer showed decreased IQE and extended exciton lifetime due to the evanescent wave property of LSPs field from colloidal Ag NPs.

Surface coverage by impact of droplets from a monodisperse spray

A novel pneumatic monodisperse spray was fabricated to validate the results of a probabilistic model and a stochastic model that were developed to predict surface area coverage of the monodisperse spray. Multiple droplets of a highly viscous 87 wt% aqueous glycerin solution were deposited on a flat, transparent, plexiglass substrate. The uniformly sized droplets (2.5 mm in diameter) impacted, spread, and coalesced on the substrate which led to the creation of a liquid sheet. Using a high-speed camera placed underneath the transparent substrate, droplet impact and resultant area coverage were recorded. When impinging droplets overlapped those already on the surface, surface tension forces pulled impacting droplets towards them, agglomerating the liquid, in a phenomenon known as drawback. The area covered by the liquid was measured from photographs using image analysis software. In the numerical models, droplets were set to impinge at random locations and drawback effects between droplets were accounted for by using a semiempirical correlation. While both models showed good agreement with the experimental results at lower area fractions, the stochastic model gave better estimates at larger area fraction due to its incorporation of drawback effects.

Исследование и разработка пневматического пистолета для распыления порошка в хирургии

The comparative analysis of modern devices for spraying of powder is carried out. The pneumatic spray of powder for use in the surgical sphere promoting healing of wounds with the increased regeneration of soft fabrics after surgical intervention with a possibility of regulation of feed rate of material is designed. The studied spray is considered as the system of pneumotransport of bulks, its main characteristics are calculated, the drawing is developed, the 3D model is constructed. The current of gas in the operating volume of the pneumatic spray is explored, the dependence of distribution of pressure is given in the operating volume of the considered device.

Influence of nitrogen doping on TiO2 nanoparticles synthesized by pneumatic spray pyrolysis method

Improving the photon harvesting efficiency of dye sensitized solar cells (DSSCs) employing TiO2 photo-anode has been the major issue since 1991. So it is very important to discover new techniques that will enhance the properties of TiO2 nanoparticles (NPs) which will then prevent recombination of the photo-generated electron hole pairs and as well as improving the visible absorption properties of the TiO2. This will in turn improve the performance of the DSSC photo-electrode. The optical, electronic and structural properties of TiO2 NPs rely on factors like morphology, surface area, particle size and the presence of beneficial defects caused by dopants. This study focuses on the fabrication and characterization of nitrogen doped TiO2 (NPs) prepared by pneumatic spray pyrolysis (PSP) technique. The un-doped and nitrogen doped TiO2 NPs were prepared using titanium butoxide as a precursor and urea as the dopant. The morphological and structural properties of PSP synthesized NPs were evaluated using SEM, EDX, Raman Spectroscopy (RS), XRD and FTIR. SEM analysis revealed that the presence of nitrogen dopant results in a significant change in the surface morphology of the PSP synthesized NPs. RS revealed the presence of Raman vibrational modes and symmetry at 158 (Eg(1)), 208 (Eg(2)), 258 (B1g), 255 (B1g) 396 (B1g), 514 (A1g + B1g(2)) and 640 (Eg(3)) belonging to a mixed Anatase-Rutile phase. XRD analysis revealed that the PSP synthesized NPs have particles sizes of 10.90 nm, 11.31 nm, 11.93 nm and 14.14 nm for un-doped TiO2, 0.005 M TiO2, 0.015 M TiO2 and 0.025 M TiO2 NPs respectively. FTIR spectra of the PSP fabricated samples exhibited a peak at 616.22 cm−1 that is assigned to Ti–O vibrational stretching of the anatase phase of TiO2. UV–vis spectroscopy revealed a decrease in energy band gap with increase in dopant level for the TiO2 samples prepared.

Porous polyimide particle-coated adsorptive microextraction bar combined with thermal desorption-gas chromatography for rapid determination of parabens in condiments

Bar adsorptive microextraction using polyimide (PI) particles as the extraction phase followed by thermal desorption and gas chromatography-mass spectrometry (BAμE/TD-GC-MS) was developed to detect parabens in condiments, such as soy sauce, vinegar, and cooking wine. The PI particles were prepared by pneumatic spray combined with the immersion-precipitation phase transformation method. The prepared particles have highly porous surfaces, on which the 10–60 nm open nanopores are closely packed. Particles between 250–500 μm were then sieved out and used as extraction phase for BAμE. In contrast to the smooth and dense surface of the conventional PI phase transformation bar, the macroscopic rough surface of the PI particle bar and its microscopic porous particle surfaces provided larger extraction interfaces and more surface adsorption sites, both of which enhanced the extraction mass flux. With an extraction time of 2 min, the absolute recoveries of parabens by the PI particle bar were 1.9˜2.7 times those obtained by the conventional PI phase transformation bar. The intrabatch and interbatch precisions of the PI particle bars were less than 4.6% and 7.5%, respectively, and the PI particle bar exhibited a long lifetime of more than 50 extraction/desorption cycles. To realize rapid determination of parabens, the extraction time was fixed at 2 min. The analytical performance for standard water samples showed wide linearity (0.14–50 μg/L) with good correlation coefficients (r > 0.9980), good precision (RSD < 5.6%), appropriate detection limits (0.005−0.008 μg/L), and high enrichment factors (305–626). For the analysis of parabens in diluted condiments, the relative recoveries were between 86.1% and 109.0% with RSDs ranging from 0.1%–8.7%.

Deposition of SnO2 buffer layer onto commercial conducting glass to be used in thin films solar cells technology

In this work the influence of the deposition of SnO2 buffer layer on the optical, electrical and morphological properties of commercial conducting glasses is presented. Previously the transparent conducting oxide (TCO) were studied in order to determine which is the most appropriate in solar cell applications. The SnO2 thin films were deposited onto glass and commercial conducting glass by pneumatic spray pyrolysis (PSP) and magnetron sputtering techniques and characterized optically and electrically. TCO/buffer bi-layers configuration were processed and characterized through a modified well-known Haccke figure of merit. The results are discussed in terms of considering the usefulness or otherwise of this configuration, depending on the morphological quality of commercial conductive glass in the processing of second-generation solar cells in thin film technology.

Analysis of motor oils using an «Ékspress» spectrometer and microwave plasma source

It is known that the working properties of motor oil are determined by the presence of some elements of the periodic table. The properties of oil can vary significantly over time due to exposure to both high and extremely low pressures and temperatures. To ensure uninterrupted long-term operation of equipment, it is necessary to monitor various indicators of oil, including the determination of wear metals on a regular basis. Two methods of determining wear metals are most widely used: an electric arc with a rotating graphite disk and inductively coupled plasma. The goal of the work was to determine wear metals in oil using a microwave nitrogen plasma source and an «Ékspress» spectrometer according to ASTM D5185-09 method. Microwave plasma was produced using an industrial magnetron with a frequency of 2.5 GHz and a microwave resonator which provided toroidal plasma shape. Nitrogen (purity of 99.6%) was used as a plasma-forming gas. In accordance with the mentioned procedure, a series of wear metal samples was prepared by adding metal oxides to the base oil for comparison with the control experiment. After that, the solutions were diluted 1:10 by weight with kerosene to eliminate the difference in viscosity of the samples and ensure their spraying using a pneumatic spray. The spectrometer allows simultaneous recording of spectra in the region of 190 – 360 and 390 – 540 nm with an integration time of 70 msec. The intensity of C2and CN molecular bands was reduced by introducing air into the intermediate flame of the burner. The constructed calibration graphs for determination of Al, Pb, Fe, Cu, Cr, Cn were used in analysis of the control sample. It is shown that wear metals in oil can be determined using microwave plasma as a source of spectrum excitation.

The substantiation of the technical solution for improving the application of chemical plant protection products using pneumohydraulic sprayers

Purpose. Improving the effectiveness of plant protection products when growing crops due to the pneumohydraulic device that ensures their uniform application to the sheet surface. Methods. Analytical and Experimental. Results. Laboratory studies of the process of spraying plants with nozzles with a pneumohydraulic system determined the quality indicators of the process with pressure in injection communication 0.4 MPa – droplet coating density of 19–46 pcs/cm2 for the weighted average droplet diameters in the different experimental variants was within 304–543 microns. These indicators were compared with those for the standard, anti-drift and injection nozzles in which the droplet coating density was 23–59 pcs/cm2 and the weighted average droplet diameters were in the range of 350–485 microns. The obtained analytical dependence of the influence of lateral air flow and air pressure in the pneumohydraulic system on the amount of deposited sprayed liquid. The annual economic effect from the introduction of this technical device with pneumohydraulic spraying system is 10434 UAH. Conclusions 1. The tendencies development technical means of chemical protection plants are determined: the use of sprayers with monodispersed cutting by drops adapted to weather conditions, which allow the operator to work in a wider range of speeds like wind (up to 9 m/s) and the speed of the unit (up to 30 km/h). To improve the quality of spraying, devices with air supply to the nozzles are used to control the dispersion of the spray depending on weather conditions. 2. It was established that with increasing pressure of air from 0.12 MPa there is a decrease in the diameter of the droplets. And at a pressure more than 0.25 MPa, the cutting is equivalent to a standard small-gap slot sprayer. During researches, it was discovered that the air pressure could be influenced by the dispersion of droplet cutting. Keywords: pneumatic hydraulic spray, model sketches, laboratory tests, performance indicators, analytical fluidity, fluid pressure, air pressure.

Structural, Morphological, Optical, and Electrical Characterization of Fluorine Doped Tin Oxide (FTO) Thin Films Synthesized by PSP

This paper reports a study of Fluorine-doped Tin Oxide (FTO) thin films deposited by the Pneumatic Spray Pyrolysis (PSP) technique. The films were deposited on glass substrates at 450 °C with a ~125 nm thickness, using an F/Sn ratio of 0, 0.2, 0.35, 0.5, 0.65 and 0.85, respectively. The samples were characterized by X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), UV-visible Spectroscopy and Hall Effect techniques, respectively. XRD results revealed that the FTO thin films were polycrystalline with a tetragonal rutile-type structure and had preferential orientations along (110) planes. SEM studies showed that FTO thin film morphology was totally affected by an increased F/Sn ratio. The calculated grain mean sizes were 10-35 nm. Optical transmittance spectra of the films showed a high transparency of approximately 80-90 % in the visible region. The optical gap of FTO thin films was in a 3.70-4.07 eV range. Electrical and optical properties of these films were studied as a function of the F/Sn ratio. Therefore, the optimal FTO (F/Sn = 0.5) films revealed a maximum value of the figure of merit approximately 8.05 × 10-3 (Ω-1) at λ = 400 nm. The high-conducting and transparent-elaborating FTO thin films may have several promising applications due to its multifunctional properties.

Deposition of SnO2 buffer layer onto commercial conducting glass to be used in thin films solar cells technology

In this work the influence of the deposition of SnO2 buffer layer on the optical, electrical and morphological properties of commercial conducting glasses is presented. Previously the transparent conducting oxide (TCO) were studied in order to determine which is the most appropriate in solar cell applications. The SnO2 thin films were deposited onto glass and commercial conducting glass by pneumatic spray pyrolysis (PSP) and magnetron sputtering techniques and characterized optically and electrically. TCO/buffer bi-layers configuration were processed and characterized through a modified well-known Haccke figure of merit. The results are discussed in terms of considering the usefulness or otherwise of this configuration, depending on the morphological quality of commercial conductive glass in the processing of second-generation solar cells in thin film technology.

Substrate temperature-dependent properties of sprayed cobalt oxide thin films

Cobalt oxide (Co3O4) thin films were deposited onto amorphous glass substrates using a home-made pneumatic spray pyrolysis system (SPT) from aqueous solution of cobalt chloride salt (CoCl2) as a source of cobalt. The films were deposited at different substrate temperatures ranging from 250 to 450 °C in steps of 50 °C. The effect of substrate temperature on structural, electrical and optical properties was studied. The characterization of samples was carried out by X-ray diffraction (XRD), UV–Vis spectroscopy, energy dispersive spectroscopy (EDS), scanning electron microscopy and four probe points measurements. The XRD study showed that all the films were polycrystalline consisting of Co3O4 spinel cubic phase. The preferred orientation of the crystallites changed from (311) to (111) when the substrate temperature increases. The average calculated grain size was about 40.38 nm. Morphological studies exposed that the films surface morphology is almost homogeneous and well-covered. Peaks associated with Co and O elements are present in EDS analysis witch confirm the composition of the films. The optical transmittance and the band gaps energy increase with the increase of substrate temperature. The measured electrical conductivity at room temperature was found in the order of 10−1 (Ω cm)−1.

Assessing the influence of air speed and liquid flow rate on the droplet size and homogeneity in pneumatic spraying.

The efficacy of treatments in vineyards largely depends on the necessary balance between leaf coverage and spray drift and, therefore, knowledge about droplet size is of major importance, but scarce scientific information is available on pneumatic spraying, often adopted in this crop. The objective of this work was to obtain the relationships between the droplet size spectra characterization parameters and the main affecting factors in pneumatic nozzles. Three liquid flow rates (LFR) and four air speeds (AS) were combined in laboratory conditions to assess their influence on the droplet size spectra (D10, D50 and D90), homogeneity (Relative Span Factor, RSF) and driftability (V100 ) in two different air shear nozzles (cannon-type and hand-type nozzles). The droplet size parameters were significantly affected by LFR and AS, and a model was fitted to predict droplet size in every spout type. The droplet V100 was also affected by both factors. The RSF was similar in both cases but did not follow regular trends. The findings obtained can help vineyard farmers and technicians to effectively increase the efficiency and, therefore, the efficacy of the pesticide treatments reducing at the same time the spray drift risk by selecting appropriately the optimal values of the main operational parameters: LFR and AS. © 2018 Society of Chemical Industry.

Accelerated tert-butyloxycarbonyl deprotection of amines in microdroplets produced by a pneumatic spray

Protection and deprotection of organic compounds in multistep reactions using functional groups such as tert-butoxycarbonyl (Boc), is widely performed in synthetic organic chemistry. Reaction rate acceleration studies in spray-based ionization methods (electrosonic spray, paper spray, nanospray) have become increasingly common. Here, we demonstrate reaction rate acceleration of Boc deprotection using easy ambient sonic-spray ionization (EASI), a pneumatic technique which does not involve an applied voltage, in a teaching laboratory setting. The goal of this laboratory exercise was to explore acceleration in a previously unexplored spray-based reaction, while emphasizing in a pedagogic setting the importance of protecting groups for multistep synthesis. Rate acceleration factors of more than an order of magnitude were observed in the uncharged micron-sized droplets generated by EASI. The effect of reaction conditions on reaction acceleration was examined including changes in the type of acid, reagent concentration ratios and syringe pump flow rates. Student knowledge was assessed by pre-laboratory assignments, post-laboratory reports and oral interviews.

Electrospraying assisted by pressurized gas as an innovative high-throughput process for the microencapsulation and stabilization of docosahexaenoic acid-enriched fish oil in zein prolamine

Zein, a prolamine obtained from maize, was employed to encapsulate a fish oil highly enriched with docosahexaenoic acid (DHA) by an innovative process termed electrospraying assisted by pressurized gas (EAPG). This technology combines high electric voltage with pneumatic spray to yield a high-throughput encapsulation process. Semi-spherical zein flowable capsules with mean sizes of 1.4 μm containing the DHA-enriched fish oil were produced by EAPG from inert ethanol solutions at room conditions, presenting a high encapsulation efficiency. The oxidative stability tests carried out in the zein microcapsules obtained by EAPG showed that the DHA-enriched fish oil was efficiently protected over storage time. Sensory tests were also performed on fortified reconstituted milk with the freshly prepared zein/DHA-enriched fish oil microcapsules, suggesting negligible oxidation effects after 45 days. The results described herein indicate that EAPG is a promising innovative high-throughput electrospraying-based methodology for the encapsulation of bioactives and, therefore, the resultant DHA-enriched fish oil containing microcapsules can be industrially applied for the formulation of fortified foods. An innovative process, termed electrospraying assisted by pressurized gas (EAPG), is herein originally presented as a novel encapsulation methodology. This technology is based on the combination of high voltage and pneumatic spray, allowing the formation of microcapsules at room temperature conditions. Thus, EAPG shows a great deal of potential to encapsulate nutraceuticals and other bioactives that are sensitive to thermal degradation and/or oxidation. The resultant bioactive-containing capsules can be, thereafter, applied to develop novel fortified food products.

Structural, electrical and optical properties of ZnO thin films produced by chemical spray using ethanol in different amounts of the sprayed solution

Transparent conductive and polycrystalline zinc oxide (ZnO) thin films were deposited on sodalime glass substrates using the pneumatic chemical spray technique with different amounts (30, 50 and 70 ml) of sprayed solution.During the synthesis, the surface of the substrates was kept at 400, 450 and 500 °C.The effects of the mentioned parameters on compositional, structural, morphological, electrical and optical properties were studied with Rutherford Backscattering Spectrometry, X-ray diffraction, Scanning Electron Microscopy, the Four Point methods and Ultraviolet and Visible Spectroscopy (UVS). The results show that the atomic Zn concentration in the films increases with the volume of sprayed solution and with the substrate temperature. The Band gap energy seems not to be sensitive to the amount of sprayed solution; meanwhile, the higher band gap energy values were obtained in the samples deposited at Ts = 450 and 500 °C. On the other hand, the lower resistivity values were observed in samples deposited with Ts = 450 °C.

Coatings Based on Nanodispersed Oxide Materials Produced by the Method of Pneumatic Spraying

New approaches are proposed, relying on which the coatings from nanodispersed oxide materials are formed on polypropylene fibers. It is shown that in the course of the viscous fluid – solid state transition of the polymer its nanoparticles are stabilized on the surface of the formed fibers.

Compositional dependence of optical and electrical properties of indium doped zinc oxide (IZO) thin films deposited by chemical spray pyrolysis

The structural and optoelectronic properties of undoped and indium doped zinc oxide (IZO) thin films grown on glass substrates through a simple reproducible custom-made pneumatic chemical spray pyrolysis technique are presented. X-ray diffraction (XRD) results showed a polycrystalline structure of hexagonal wurtzite phase growing preferentially along the (002) plane for the undoped sample. Increase in dopant content modified the orientation leading to more pronounced (100) and (101) reflections. Optical transmission spectra showed high transmittance of 80–90% in the visible range for all thin films. The optical band gap energy (Eg) was evaluated on the basis of the derivative of transmittance (dT/dλ) versus wavelength (λ) model and Tauc's extrapolation method in the region where the absorption coefficient, α ≥ 104 cm−1. The observed values of Eg were found to decrease generally with increasing In dopant concentration. From the figure of merit calculations a sample with 4 at.% In dopant concentration showed better optoelectronic properties.