Substrate Distance Research Articles

Zinc sulfide thin films produced by spray pyrolysis: optical and structural characteristics

Zinc sulfide thin films were prepared using the economical spray pyrolysis process. A thin film of exceptional quality with a temperature difference of 300 °C to 400 °C is produced by optimizing variables such as concentration, flow rate, and nozzle to substrate distance. These films' optical characteristics and structure were examined. The deposited thin films displayed a direct and allowed transition, as indicated by the optical transmittance spectra. XRD analysis confirmed that the deposited thin films were polycrystalline with a cubic phase. This film can be used in solar cell applications since the band gap energy fluctuation is high enough, ranging from 3.42 to 3.81 eV.

Unlocking the thermoelectric potential of nanocrystalline magnesium selenide thin films grown by single stage horizontal tube furnace (SSHTF)

In this manuscript, the thin films of Magnesium Selenide (MgSe) were synthesized on a glass substrate using a single-stage horizontal tube furnace (SSHTF) which is supposed to be the simplest and a cost-effective approach. Before the deposition of thin films, the substrate was cleaned using standard methods. A pellet was formed by taking an equal ratio (1:1) of magnesium (Mg) and selenium (Se) powders and then evaporating them at 700oC for 1 h. The flow rate of nitrogen gas (100 SCCM) was maintained during the deposition process to avoid unwanted oxygen. A number of samples were synthesized by varying the source to substrate distance, and some representative samples are chosen for this study. The post-growth samples were characterized using XRD, SEM, and Raman Spectroscopy. The thermoelectric potential of all samples was tested by a home-developed Seebeck system. We have observed some promising values of the Seebeck coefficient (7.175 × 10−5 V/°C) and power factor (6.35 × 10−8 Wm−1oC−2) at optimized source-to substrate distance. These encouraging results will open the door for MgSe-based thermoelectric research and further explore its power generation potential in the future.

Tidal Impoundment and Mangrove Dieback at Cabbage Tree Basin, NSW: Drivers of Change and Tailored Management for the Future

Major storms can cause significant changes to coastal and wetland environments. A series of storm events in 2020 resulted in closure of the historically open estuary at Cabbage Tree Basin, Port Hacking, New South Wales (NSW), Australia. Prolonged tidal impoundment (3 months) led to substantial changes in hydrological and sedimentological processes, resulting in widespread mangrove dieback. This study aimed to quantify the degree of impact and recovery for mangroves, identify factors contributing to dieback, and consider the implications for carbon sequestration. This was achieved using remotely piloted aircraft structure-from-motion approaches, aerial photography, and field-based assessments of vegetation health and above-ground biomass (AGB). Mangroves were classified as ‘dead’, ‘partially dead’, and ‘live’. In October 2019, there was 10.8 ha of live mangroves, with this reduced to 6.6 ha by August 2022. Digital surface models (DSMs) were intersected with classified mangroves to assess the vertical distribution of each zone. All mangroves classified as ‘dead’ were distributed at elevations < 0.4 m with respect to the Australian Height Datum (AHD), suggesting these regions were persistently inundated, which was confirmed by water level loggers (inundated during logger deployment). Field data confirmed substrate elevation related to dieback with the proportion of ‘live’ mangroves greatest at elevations > 0.6 m AHD. Substrate elevation and distance to the estuary mouth were significantly correlated with species, with Avicennia marina located at lower tidal positions and closer to the entrance compared to Aegiceras corniculatum. The dieback event equated to a loss of 81.5 ± 48 Mg of above-ground biomass, 38.1 ± 22.5 Mg C, or 140 ± 82 Mg CO2 equivalence (CO2e). This study provides an important baseline for monitoring dieback events. Continued monitoring is crucial to assess recovery and to tailor management strategies.

Growth and characterization of tin disulphide thin film by spray pyrolysis technique

An inexpensive spray pyrolysis process has been used to create thin layer of tin disulphide. The concentration, flow rate, and nozzle to substrate distance were tuned as deposition parameters to produce high-quality thin films. Temperature is varied in the range 200˚C to 350˚C. Through physical research, properties such as the structural, electrical and optical were examined. The films generated are SnS2 with a hexagonal structure, as revealed by X-ray diffraction. EDAX analysis confirms SnS2 thin films. Scanning electron microscopy indicated uniform stacking and material adherence to the glass substrate. A 2.22 eV straight band gap was found. Two peaks in the photoluminescence spectrum were indicative of the emission of green and yellow fluorescence, respectively. Electrical properties reveal that resistivity decreases from 3.18 x 10-2 Ω cm to 3.06 x 10-3 Ω cm, carrier concentration &amp; mobility increases to 1.4 x 1020/ cm3 to 1.8 x 1020/ cm3 , 1.92 cm2 /Vs to 5.3 cm2 /Vs respectively with increases in temperature.

Rational Comparison of Anode Material Properties for Anion Exchange Membrane Water Electrolysis

Due to the increasing need for sustainable energy, the hydrogen (H2) economy is a topic of interest where H2 is used for energy storage and as a fuel [1]. In this regard, the utilization of hydrogen as a promising energy source for achieving global decarbonization goals has led to the exploration of water electrolysis (WE) as a viable route for producing green hydrogen [2,3]. Although proton exchange membrane water electrolysis (PEMWE) is established, they suffer from the reliance on expensive noble metals as catalysts. In contrast, recently, anion exchange membrane water electrolysis (AEMWE) is emerging as a low-cost alternative solution that combines the strengths of both alkaline, WE (low capital cost and use of liquid electrolyte), and PEMWE (low ohmic resistance and high gas purity) where cost-effective transition metal oxides can be used [4-5].Among various materials that are being investigated as AEM anodes, Ni-based systems show high promises. However, a rational comparison between different Ni-based benchmarks as AEM anodes under different stages of electrode production is still lacking. Such a comparison would provide insight into the material properties that are relevant for optimization in each stage thereby producing highly performing catalysts. To achieve this, these materials have to be processed under comparable conditions during the electrode fabrication to draw meaningful correlations between the performance and influencing parameters.Herein, we developed a protocol for rationally comparing different commercial benchmark anode materials in AEMWE. The aim is to understand material properties that influence the final catalyst performance and further enhance their catalytic activity by fine-tuning pivotal material properties. We selected Ni-Co-O, Ni-Fe-O, and Ni-Co-O doped by Fe as potential anode materials for AEMWE and performed a systematic evaluation and comparison of the properties in powder, ink, and electrode layer stages.After the initial characterization of the powders by complimentary techniques such as X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM), we developed ink formulations from each material. The stability of dispersions in various solvents was assessed using Hanson Solubility Parameters extracted from Analytical Centrifugation (AC) data [6]. AC in conjunction with own developed algorithms were then used to represent long-term stability data as transmittograms. During the ink development, particular care was taken to use solvent matrices that lead to comparable particle size distributions within the materials library together with constant catalyst to binder ratio and ink processing (e.g., ultrasonication) to assure the properties of each material to be the only free parameter in both ink formulation and electrode development. In the subsequent step, electrode layers from each material were obtained by spray deposition with defined deposition parameters (substrate temperature, ink flow and nozzle to substrate distance) that enabled the achievement of comparable electrode layers. These layers were characterized by atomic force microscopy and N2 sorption for understanding the microstructure and specific surface area of each electrode which was used for normalizing the electrochemical data. Specifically, an own developed AFM-based multi-stage data quantification was applied for evaluating the microstructure on larger scales [7]. Finally, the electrochemical performance of these materials as anodes in AEMWE were tested and correlated with the inherent material properties as well as ink and electrode layer characteristics.This work sheds light on a systematic workflow for characterizing AEMWE anode materials at different stages which provides a comprehensive picture about the underlying property-performance relationship. The developed coherent workflow can be expanded to other materials in AEMWE. Staffell, Iain, et al. "The role of hydrogen and fuel cells in the global energy system." Energy & Environmental Science 12.2 (2019): 463-491.Kusoglu, A., Chalkboard 1-the many colors of hydrogen. The Electrochemical Society Interface, 2021. 30(4): p. 44.Harkema, D., G. Palasantzas, and J. Miocic, Hydorgen in the European energy transition: Where will it come from? 2022.Miller, H.A., et al., Green hydrogen from anion exchange membrane water electrolysis: a review of recent developments in critical materials and operating conditions. Sustainable Energy & Fuels, 2020. 4(5): p. 2114-2133.Santoro, C., et al., What is Next in Anion‐Exchange Membrane Water Electrolyzers? Bottlenecks, Benefits, and Future. ChemSusChem, 2022. 15(8): p. e202200027.Bapat, S., et al., Towards a framework for evaluating and reporting Hansen solubility parameters: applications to particle dispersions. Nanoscale Advances, 2021. 3(15): p.4400-4410.Jain, A., et al., "Small-Area Observations to Insight: Surface-Feature-Extrapolation of Anodes via Multistage Data Quantification. " Under review, ChemCatChem

Controlled Morphological Growth and Photonic Lasing in Cesium Lead Bromide Microcrystals.

Morphology plays a crucial role in defining the optical, electronic, and mechanical properties of halide perovskite microcrystals. Therefore, developing strategies that offer precise control over crystal morphology during the growth process is highly desirable. This work presents a simple scheme to simultaneously grow distinct geometries of cesium lead bromide (CsPbBr3) microcrystals, including microrods (MR), microplates (MP), and microspheres (MS), in a single chemical vapor deposition (CVD) experiment. By strategically adjusting precursor evaporation temperatures, flux density, and the substrate temperature, we surpass previous techniques by achieving simultaneous yet selective growth of multiple CsPbBr3 geometries at distinct positions on the same substrate. This fine growth control is attributed to the synergistic variation in fluid flow dynamics, precursor substrate distance, and temperature across the substrate, offering regions suitable for the growth of different morphologies. Pertinently, perovskite MR are grown at the top, while MP and MS are observed at the center and bottom regions of the substrate, respectively. Structural analysis reveals high crystallinity and an orthorhombic phase of the as-grown perovskite microcrystals, while persistent photonic lasing manifests their nonlinear optical characteristics, underpinning their potential application for next-generation photonic and optoelectronic devices.

Wear-Resistant Low-friction Atmospheric Pressure Plasma Spray Coatings for Sustainable (Bio-based Recyclable) Materials

Coatings from polyetheretherketone (PEEK), polyamide 12 (PA12), molybdenumdisulfide (MoS2), zinc (Zn), and graphite (C) powder mixtures were deposited on PA6, PA12, and PEEK substrates by an atmospheric pressure plasma (APP) spray jet system. Several tenth of µm thick coatings on PA6 and PA12 substrates result in an almost halved surface roughness Ra ~8 µm, Rq ~10 µm and Rz ~60 µm, whereas a significant increase of all surface roughness parameters is observed for PEEK substrates (Ra < 1 µm → 4 µm, Rq < 1 µm → 5 µm, Rz < 5 µm → 20 µm). The surface roughness, powder composition, and selected APP process parameter strongly influence the coefficient of friction (COF) and specific wear rate ki of the APP coatings in rotational ball-on-disc tribological testing. The COF of PA12/MoS2/C coatings on PA6 substrates manufactured by selective laser sintering (SLS) is ~0.2 after 628 m sliding distance, resulting in a very low calculated ki of 6.3 × 10−7 mm3/Nm. A similarly low COF and ki was observed for PEEK coatings deposited at a current of 75 A and 60 mm jet–substrate distance on SLS PA12 substrate. Although the COF of Zn/C/MoS2 coatings on PEEK drops down below 0.1 after 1884 m sliding distance under nitrogen atmosphere the corresponding ki of 5.6 × 10−5 mm3/Nm is higher. Still all calculated specific wear rates are significantly lower than the reported values of polyamide-polytetrafluorethylene (PTFE)-polyethylene composites (1.9–8.0 × 10−2 mm3/Nm) and partly even outperform PEEK-PTFE composites (1.0 × 10−7–2.5 × 10−6), currently applied in demanding wear regimes.

Realizing the giant seebeck coefficient and electrical conductivity in SnTe thin films by grain engineering

In this work, we have modulated the film growth parameter (post growth annealing) of SnTe-based thin films to enhance the charge carrier transport by controlling the morphology and microstructure. The samples under investigation were prepared by a vacuum tube furnace on a glass substrate using following growth conditions; growth temperature 700 °C, pressure in the tube 180 mTorr, source to substrate distance 7 cm. Grain engineering was performed by annealing the samples at different temperatures (200–500 °C) which was used as a powerful tool to enhance the mobility of charge carriers (7–13 cm2/V-Sec). SEM images demonstrated that a representative sample annealed at 300 °C has a layered structure, therefore the carriers in this sample possessed the highest value of mobility. This encouraging value of carrier mobility resulted in the enhancement of the Seebeck coefficient (7600 μV/K) and electrical conductivity (5S/cm) simultaneously. XRD and Raman spectroscopy measurements were also performed to crystal structure and vibrational modes of annealed SnTe thin films. In conclusion, it is reported that the annealing temperature of 300 °C is supposed to be the optimal value for required grain engineering in order to realize the highest value of the Seebeck coefficient and electrical conductivity.

Deuterium retention in co-deposition with lithium in Magnum-PSI: experimental analysis and comparison with SOLPS-ITER

The vapor-box, a liquid metal design for the divertor, utilizes lithium recirculation through evaporation and condensation. Safety concerns arise from Li-D/T formation and co-deposition on vapor-box walls and the first wall, affecting tritium retention. Additively manufactured tungsten capillary porous structure (CPS) samples with Li were exposed to high heat flux D plasmas in the linear plasma device Magnum-PSI, to study D retention in Li–D co-deposition dependence on substrate temperature (200 ∘ C–428 ∘ C) and distance from the plasma beam center (25–85 mm). The D:Li ratio was determined via in-situ ion beam diagnostics with simultaneously analyzed Nuclear Reaction Analysis and Elastic Backscattering Spectroscopy spectra to maximize the precision. Experimental results approach close to the theoretical maximum at 40:60 D:Li ratio and deposited film thickness ranging from 0.02 to 3.2 µm. Witness plate temperatures above 400 ∘ C yielded Li films under 150 nm in thickness with lower D:Li ratios (5:95 D:Li ratio). At this temperature LiD decomposition pressure is comparable with vessel pressure during plasma. SOLPS-ITER simulations narrowed CPS surface temperature to 650 ∘ C–700 ∘ C, indicating Li+ plasma dominance near the target surface. Redeposition ratio of lithium on the CPS surface was determined to be around 80 % , matching quartz crystal microbalance results. However, SOLPS-ITER simulations lacked accuracy in recreating observed Li and D deposition layers on WPs, improvements are needed to model plasmas with significant Li quantities. Extension of SOLPS-ITER simulations to include LiD molecules and enhance heat flux accuracy is crucial for better alignment with experimental data.

Potensi Pewarna Alami untuk Pengembangan Kemajuan Teknologi Sel Surya Organik

Electrospinning is a modified technology to produce nano-sized fibers which can be used in making thin layers of semiconductor dye sensitized solar cells. Flourate – doped tin oxide (FTO) substrate was placed as a target for deposition of TiO2 nanofiber synthesized from TiO2 solution. The deposition process of a thin layer of TiO2 nanofiber was carried out for 15 minutes. The TiO2 solution synthesized is a mixture of acetic acid, ethanol, polyvinylpyrrolidone (PVP), and titanium tetra – isopropoxide (TTIP). Mixing the synthesis solution was carried out for 24 hours, to obtain a homogeneous TiO2 synthesis solution. The TiO2 nanofiber thin layer deposition process was applied under an electrospinning voltage of 25 kV, the distance of the FTO substrate as the collector layer to the solution syringe was 25 cm to avoid too large solution droplets. Before the deposition stage, the surface of the FTO substrate is first formed using the etching method by coating Zn and removing the conductive layer using HCl, so that a customized conductive layer is obtained. The annealing process of the deposited TiO2 nanofiber layer was carried out for 3 hours at a temperature of 450°C. The spin coating method was carried out to deposit a layer of Poly [2- methoxy- 5- (2- ethyl hexyloxy)- 1,4- phenylene venylene] (MEH-PPV). Coating variations are carried out with 4 different layer thicknesses. MEH – PPV was prepared by mixing chlorobenzene and stirring for 18 hours. Testing and characterization was carried out using current and voltage characterization (I – V meter), as well as image characterization using Scanning Electron Microscopy (SEM) as an analysis of the influence of layers on organic solar cells.

Giant Seebeck coefficient in SnTe thin films grown by thermal evaporation using layered structure engineering

In this work, we have reported a giant Seebeck coefficient (8033 µV/K) in SnTe thin films by controlling the layered structure using post growth annealing technique. The samples used in the current study were synthesized using a vacuum tube furnace having an evaporation temperature 700 °C, base pressure 180 m Torr and source to substrate distance 7 cm. Sn and Te metal powders with an equal weight ratio were evaporated on the glass substrate to form SnTe composite. Post-growth annealing in vacuum environment was performed for different time’s duration of 1–4 h with a step of one hour. XRD analysis reveals six diffraction peaks for all samples, which correspond to different crystal planes of SnTe structure. Raman spectra exhibit the presence of specific vibrational modes associated with SnTe. Using the giant value of Seebeck coefficient and moderate electrical conductivity, a strong power factor value of 8.1 × 10−3 W m−1 K−2 was observed for optimized sample (annealed for 3 h). The strongest values of Seebeck coefficient and power factor are supposed to be the layered structure of SnTe thin films which was verified by the SEM images.

Angular distribution of species in pulsed electron beam deposition of BaxSr1-xTiO3

The angular thickness and composition profiles of thin films obtained by irradiating a BaxSr1-xTiO3 (x = 0.2) target with a pulsed electron beam were investigated by Rutherford backscattering spectrometry for argon and oxygen background gases at a pressure of about 10-2 mbar. A “semi-sphere” holder was used, resulting in a fixed target to substrate distance of about 40 mm. The film thickness profiles have forward shaped peaks, with measurable thickness up to 80-90° for major axis and 25° for minor axis, and presents similar trend for both argon and oxygen background gas. The analysis of the congruent transfer of the elements from the target as a function of the angle showed that the film composition is not uniform over this wide angular range and differs with respect of the ablated target depending on the element used and on background gas.

Fitting Kinetics of Arbitrarily-Shaped Finite Reactive Features Using Their Scanning Electrochemical Microscopy Images

Computer modelling of scanning electrochemical microscopy (SECM) images allows for the kinetics of chemical reactions at surfaces to be fit. Until recently, methods for fitting kinetics from SECM images of reactive features required models with custom geometries that approximated the feature shape.[1,2] The kinetics of arbitrarily-shaped features can be fit by discretizing the surface into pixels and modelling the surface rate constant of a reaction as a discrete function. The shapes of the underlying reactive feature responsible for hot spots in an SECM image were determined by deconvolution,[3] edge detection,[4] or microscopy and were used to control the surface reaction boundary condition in finite element method simulations. The use of deconvolution or edge detection to obtain an estimate for the shape of the underlying features seen in SECM images was of particular interest since they did not require any characterization of the surface beyond SECM.Simulated SECM images of reactive features on flat surfaces were controlled using three parameters: the tip to substrate distance of the scanning electrode, the rate constant for the reaction at the surface feature and the erosion and dilation of the initial estimate of the shape of the reactive feature. The parameters of these SECM images were optimized such that the simulated images fit experimental SECM images to obtain shape and kinetic information of reactive sites.The ability to accurately fit arbitrarily shaped features dramatically broadens the scope of reactive features that can be treated to include features of interest such as grain boundaries, scratches and irregularly shaped inclusions.[1] Filice, F. P.; Li, M. S. M.; Ding, Z. Simulation Assisted Nanoscale Imaging of Single Live Cells with Scanning Electrochemical Microscopy. Adv. Theory Simul. 2018, 2, 1800124[2] Leslie, N.; Mena-Morcillo, E.; Morel, A.; Mauzeroll, J. Fitting Kinetics from Scanning Electrochemical Microscopy Images of Finite Circular Features. Anal. Chem. 2022, 94, 44, 15315–15323[3] Stephens, L. I.; Payne, N. A.; Mauzeroll, J. Super-resolution Scanning Electrochemical Microscopy. Anal. Chem. 2020, 92, 3958– 3963[4] Stephens, L. I.; Payne, N. A.; Skaanvik, S. A.; Polcari, D.; Geissler, M.; Mauzeroll, J. Evaluating the Use of Edge Detection in Extracting Feature Size from Scanning Electrochemical Microscopy Images. Anal. Chem. 2019, 91, 3944– 3950

Evolution Mechanism of Sputtered Film Uniformity with the Erosion Groove Size: Integrated Simulation and Experiment.

In this work, Cu thin films were experimentally fabricated at different target-substrate distances by 2-inch and 4-inch circular planar magnetron targets. Meanwhile, the sputtering deposition of Cu thin films was investigated via an integrated multiscale simulation, where the magnetron sputtering discharge was modeled using the Monte Carlo (MC) method, and the sputtered particle transport was simulated using a coupled Monte Carlo (MC) and molecular dynamics (MD) method. Experimental results indicated that, as the target-substrate distance increased from 30 to 120 mm, the film thickness distribution of the 2-inch target sputtering changed from a bell-shaped curve to a line-shaped curve, while that of the 4-inch target sputtering varied from a saddle-shaped curve to a line-shaped curve. The simulation results were accordant with the experimental results. The simulation results revealed that, at a target-substrate distance of 30 mm, the sputtering particle flow from the 2-inch target overlapped strongly near the substrate center, leading to a bell-shaped film thickness distribution, while the increased diameter of the erosion groove on the 4-inch target reduced the superposition effect of the sputtering particle flow near the substrate center, resulting in a saddle-shaped film thickness distribution. In addition, when the target-substrate distance ranged from 30 to 120 mm, the film thickness uniformity of 4-inch target sputtering was superior to that of 2-inch target sputtering, and the underlying mechanism was discussed in detail.

Preparation and Innovative Design Applications of Paper-Based Aluminized Film

The growing demand for sustainable and innovative materials in product design has spurred interest in unconventional resources. Despite this, a gap persists in the effective utilization of paper-based materials, particularly with metallic coatings, for creative applications. This study aims to address this by exploring the technical methods for applying Aluminum (Al) coatings to paper substrates. We developed paper-based aluminum coatings and combined them with corrugated cardboard to create a novel material for product development. Utilizing high-strength specialty paper as the substrate, an orthogonal experiment was conducted to identify key process parameters. Factors such as target–substrate distance, working pressure, current intensity, and coating duration were evaluated for their impact on the properties of the Al film. Our research culminated in the production of high-quality Al-plated corrugated cardboard. Capitalizing on its unique attributes, we employed a design approach that led to the creation of innovative furniture featuring structural forms like folding and insertion. This study not only introduces a new range of Al-plated corrugated cardboard products but also expands the potential applications of paper-based aluminized film in material-based product design.

The evolution of preferred orientation and morphology of AlN films under various sputtering parameters

Wurtzite aluminum nitride (AlN) films with (100) and (002) preferred orientations are obtained on Si (100) wafers by radio frequency magnetron sputtering. The effects of target to substrate distance (TSD), RF power, deposition pressure and substrate temperature on crystal orientation and morphology of AlN films are analyzed. It is demonstrated that the TSD is the key factor affecting the preferred orientation of AlN films. The preferred orientation transforms from (002) to (100) with the increase of TSD. Further increase of substrate temperature and RF power causes the coexistence of (002) and (100) orientation. The evolution of orientation is explained by the change in kinetic energy of sputtered particles. The correlation between the crystal orientation and the surface morphology is investigated.

Synthesis of binder-free nanostructured MoS2 films for optoelectronic applications

The binder-free polycrystalline nanostructured molybdenum disulfide (MoS2) films are synthesized on glass substrates placed at 15, 16 and 17 cm with respect to source material by powder vapor transport technique. The X-rays diffraction analysis confirms the development of different diffraction planes related to MoS2 and Mo2S3 phases. The formation of surface morphologies (nano-boxes and nano-fibers) of MoS2 films is associated with increasing substrate distances. The changes in reflectance (0.18–0.09), refractive index (2.52–1.91), energy band gap (1.62–2 eV), Urbach energy (0.61–1.11 eV), dielectric constant (7-5.6), dissipation factor (0.04–0.06), surface/volume energy loss functions (0.0017–0.005/0.002–0.005), optical & electrical conductivities (1.23–2.04 × 1014 s−1 and 9.86–6.70 × 1019 S m−1), single oscillator energy (5.70–3.36 eV), dispersion energy (26.45–5.80 eV), nonlinear and static refractive index (0.041–1.58 × 10−5, 5.64–2.72), linear & nonlinear optical susceptibilities (0.37–0.14 and 0.011–6.16 × 10−6) are strongly associated with increasing substrate distances. Results indicate that the synthesized MoS2 films can be used in optoelectronic and solar cell devices.

Combination of different nozzle concepts for simultaneous optimization of heat transfer and its uniform distribution in convection drying applications

Precise coating processes demand sensitive drying processes. The present work investigates the operation of hybrid convective drying nozzles for combining impingement nozzles with impingement-free nozzles. Impingement-free nozzles show good uniformity, whereas impingement nozzles are characterized by higher heat transfer but greater non-uniformity across the pitch. Volumetric flow ratio between the nozzle types, lateral distance, substrate distance and angle of impingement are the parameters of this study. Compared with purely impingement-free nozzles, the combination can achieve increased heat transfer with moderate losses in distribution uniformity. A divergent impingement jet with a small lateral distance and a small substrate distance proves to be advantageous. In addition, a consideration of energy requirements shows that impingement-free nozzles, due to their lower resistance, can deliver the same volume flow rates with lower blower power. As a result, the reduction of the impingement component in the hybrid nozzle is advantageous in terms of energy.

Preparation of ZnO Piezoelectric Thin-Film Material for Ultrasonic Transducers Applied in Bolt Stress Measurement

The measurement of bolt preload by using ultrasound can be accurate, convenient, and can realize the real-time monitoring of the change in the residual axial stress of a bolt during use. In order to realize the ultrasonic measurement of bolt preload, the use of zinc oxide (ZnO) piezoelectric thin-film material as an ultrasonic transducer material to stimulate an ultrasonic signal on the bolt is a feasible solution. In this paper, we choose to use RF magnetron sputtering technology to prepare ZnO piezoelectric thin-film materials and study the effects of sputtering power and target substrate distance on the structure and ultrasonic properties of ZnO piezoelectric thin films during the preparation process, in order to lay the foundation for realizing the application of ZnO piezoelectric thin films in the field of bolt preload measurement. The experimental results show that too-large sputtering power or too-small target substrate distance will result in the particles having too much kinetic energy during sputtering and exhibiting a structure of multiorientation growth, which excites ultrasonic longitudinal–transverse waves. A sputtering power of 600 W, sputtering time of 4 h, and target substrate distance of 100 mm are ideal experimental parameters for a ZnO piezoelectric thin-film material to be excited by an ultrasonic longitudinal wave signal, and its ideal operating frequency is 41 MHZ. These research results of bolt stress detection demonstrate good application prospects.

Fabrication of Low-Temperature Solid Oxide Fuel Cells via Development of Magnetron Sputtering Process

We herein report the development of the sputtering process for the fabrication of thin film low-temperature solid oxide fuell cells (LT-SOFCs) supported by anodized aluminum oxide (AAO). The process development has been conducted for each component, anode, electrolyte, electrolyte/cathode interlayer, and cathode to achieve not only high performance but also durability. In order to fabricate catalyst-ion conducting anode cermet, Ni and GdCe co-sputtering is utilized. Since the AAO is an electrical insulator, the electrons produced from the anode requires to pass through the thin anode layer to be collected which can lead to high current collecting resistance. Therefore, sputtering conditions such as power, pressure, and time are adjusted to produce the anode with minimal ohmic loss stemming from current collection. For the electrolyte (YSZ) and interlayer (GDC), a ceramic sputtering recipe has been developed to achieve high density and uniformity, which are the most critical requirement for these components. Through optimization of the gun angle, power, pressure, and the target to substrate distance (TSD), a highly dense and uniform ceramic electrolyte can be deposited on various AAO substrate sizes. For the cathode, a mixed ionic electronic conducting cathode sputtering recipe has been developed to enhance oxygen reduction reaction (ORR) at low operating temperatures. We have been developing the sputtering process to fabricate a nanocrystalline and highly porous LSC-GDC cathode with desired microstructure to enhance the ORR activity. Through the integration of the aforementioned sputtering process development, durable and high performance LT-SOFCs have been successfully fabricated on AAO substrates up to 15cm x 15cm size. Suppered thin film cells have shown superior performance at low operating temperatures, e.g., peak power density of 1.5W/cm2 at 550oC with hydrogen fuel.