Optimization Of Deposition Parameters Research Articles

Plasma-Polymerized Thiophene-Reduced Graphene Oxide Composite Film Sensor for Ammonia/Amine Detection at Room Temperature

Industrialization has led to an increasing need for specific and selective gas sensors in the past few decades. Environmental monitoring of certain volatile compounds such as ammonia is necessary. Advancements in the food storage sector have created the need for cheap and effective amine chemosensors. Classical chemosensors still face several issues, such as a lack of selectivity and low sensitivity toward ammonia and amines. Sensitivity is defined as the relative change in response expressed in percentage. In this work, we have resolved a few issues associated with the ammonia and amine sensors, such as low selectivity, long-term instability, and unreliability under higher temperatures using plasma-polymerized thiophene (PPTh) reduced graphene oxide (rGO) composite films. PPTh films were prepared using RF plasma polymerization with optimized deposition parameters. Several samples were evaluated for their sensing response to understand the optimal PPTh and rGO ratio in the PPTh-rGO composite. These composite PPTh-rGO films have shown 4 times higher sensitivity for ammonia/amines than individual PPTh and rGO films. Ammonia, methylamine (MA), dimethylamine (DMA), and trimethylamine (TMA) were primary analytes and tested for sensing response of the PPTh-rGO composite. The sensitivity measured ranges from 1328 for trimethylamine to 2354 for methylamine at 1000 ppm. The order of sensitivity was found to be MA > Ammonia > DMA > TMA. Polymer swelling, reduced charge carriers, and disruption of conductive pathways can explain possible sensing mechanisms. PPTh-rGO composite films have shown selectivity as high as 110 for ammonia/amine over other commonly used volatile organic compounds. The sensing response of these films is stable for any temperature fluctuations from 30 °C to 150 °C. Additionally, films showed stable sensitivity for over 4 months. Thus, composite films of PPTh-rGO can be effectively used to develop highly selective and stable gas sensors for the environmental monitoring of ammonia/amines.

Regression analysis and optimization of direct energy deposition parameters for functionally graded 316L stainless steel-tungsten carbide coatings

In this study, the manufacturing of a two-layered functionally graded 316L stainless steel-tungsten carbide coating using directed energy deposition was investigated. The aim was to determine the optimal deposition parameters to achieve minimum porosity using a thickness of 1mm per layer. The input factors considered were laser scanning power and scanning speed, which were varied at different levels according to a full factorial design of an experimental matrix. To determine the optimum parameters regression analysis using analysis of variance was carried out. The optimum parameters were found at a laser scanning power of 607.4 W and a scanning speed of 8.5 mm/s for the first coated layer, and at a laser scanning power of 700 W and a scanning speed of 11 mm/s for the second coated layer. Minimum porosities of 0.0065 % and 0.0554 % were achieved for each coated layer respectively.

Influence of Wire Arc Additive Manufacturing Beads’ Geometry and Building Strategy: Mechanical and Structural Behavior of ER70S-6 Prismatic Blocks

Wire arc additive manufacturing (WAAM) with high deposition rates has attracted industry interest for the demonstrated economic production of medium-to-large-scale metallic components. The structural integrity and mechanical properties of the built parts depend on the selection of the optimum deposition parameters and the tool path strategy. In this study, an alternate orthogonal deposition strategy was employed. The influence of the beads’ geometry and the associated heat input on the mechanical and structural behavior of mild steel (ER70S-6) were investigated. The influence of the bead width (BW) and the overlapping percentage (OP) between the adjacent beads on the average and layer-by-layer hardness of the blocks along the building direction were evaluated. Tensile strength was also characterized. The alternate orthogonal building strategy enhanced the geometrical uniformity of the built blocks and the microstructural isotropy along the building direction. Increasing the BW increased the total heat input per bead per layer, which significantly reduced the hardness and tensile strength of the built blocks by 19% and 17% compared to 8% and 7% when increasing the OP, respectively. Total heat input, number of heating cycles, and cooling rates triggered the phases formed, and their morphologies along the building direction were also characterized.

Enhanced electrochemical and mechanical performance of BN reinforced Ni-P based nanocomposite coatings

Adequate corrosion protection and improved mechanical properties are necessary requirements to overcome operational costs in the industries. Ni-P based coatings are known to possess better superior corrosion resistance than its counterparts. Boron Nitride nanoparticles (BNNPs) are well known refractory material with higher hardness and chemically inert nature suitable for reinforcement. In the current investigation, the effect of incorporation and increasing concentration of BNNPs in Ni-P matrix in thoroughly investigated in terms of mechanical and electrochemical performances. Successful incorporation of BNNPs within the Ni-P matrix was achieved by employing tailored Watts bath and optimized deposition parameters. The addition and increment of BNNPs reveal a significant impact on the characteristics of pure Ni-P coatings. Improvement in the structural, morphological, mechanical and corrosion behavior of BNNPs reinforced nanocomposite coatings can be ascribed to uniform incorporation of BNNPs in the deposit leading to the dispersion hardening effect that enhances strength to the coating improving surface hardness up to 58 % in comparison to pure Ni-P coating. Moreover, reduction in the active area caused by inert BNNPs leads to the improvement in corrosion resistance properties with protection efficiency ( PE %) reaching up to 95 % for Ni-P-1.5 g/L BN nanocomposite coating in comparison to the bare mild steel substrate. BNNPs reinforced Ni-P based nanocomposite coatings provide a possible choice for their application in many industries like in the aerospace, automotive, marine, oil and gas industry. • Ni-P-BN based nanocomposite coatings are produced through electrodeposition. • Effect of incorporation and increment of BN nanoparticles are investigated. • Mechanical properties are observed to improve due to dispersion hardening effect. • Corrosion resistance is enhanced by inert BN nanoparticles by reducing the active area.

Influence of WAAM-CMT deposition parameters on wall geometry

The Wire and Arc Additive Manufacturing has called attention due to its potential in allowing the buildup of high integrity metallic parts using the commonly available welding robots in the industry. However, such a technology still presents some challenges, mainly related to obtaining optimal deposition parameters, which result in consistent layer geometry which leads to the robot and the welding power source programming. In this sense, the objective of this work is to analyze the influence of the parameters in bead and multi-layer wall geometries fabricated by the Cold Metal Transfer process to select the configurations that result in the best deposition control. The study was carried out in four steps: (i) deposition of single beads on plate, varying wire feed speed and travel speed that would result in stable and sound beads; (ii) deposition of five layer walls, considering both unidirectional and bidirectional path strategies, with and without stops between layers; (iii) deposition of ten and twenty layer walls, refining deposition parameters; and (iv) deposition of a one hundred layer wall, with the best parameter configuration among the previously tested, with bidirectional continuous strategy. The results showed that the geometry produced with a mean current of 62 A and torch travel speed of 8 mm/s along each layer and 24 mm/s on the transition between layers generated the best results, considering the natural cooling conditions. Also, the bidirectional path deposition presented the most regular geometries, when compared to the unidirectional strategy.

Reactive Spray Deposition Technology As an Alternative Method for Precious Metals Deposition on Sintered Titanium Porous Transport Layers for Application in Advanced Proton Exchange Membrane Water Electrolyzers

The metal layer deposition technologies have been revolutionized throughout the years. One of the most common forms of thin metal film deposition techniques is Physical Vapor Deposition (PVD). Within the category of PVD, there are many modifications based on the source of deposition. Among all PVD variations, the Electron Beam Physical Vapor Deposition (EB-PVD) has the advantages of higher deposition rates, the ability to deposit a wide range of high purity metals for high purity films, and the creation of continuous film layers. [1,3]. EB-PVD is better known as a thermal vaporization technique. Thermal Vaporization focuses on a source, in this case an Electron Beam (EB), which bombards the desired source material with electrons. The electron beam increases the temperature of the porous metal source until it reaches its vapor phase. The metal vapor is then condensed onto the surface of the substrate holder perpendicular to the source material. While EB-PVD is known for its advantages of higher material utilization efficiency, higher deposition rates, and better step coverage [1], it lacks in its ability to penetrate into the volume of Porous Transport Layer (PTL) or coat surfaces that are not perpendicular to the source. This is important as the PTL is in contact with a corrosive environment, which causes metal corrosion and degradation of the PTL at the surfaces that are not protected by the coating.A key aspect plaguing the thin film deposition techniques is the ability to penetrate deep into the volume of a PTL and provide full coating of the porous material, including surfaces not perpendicular to the source. In an attempt to find a solution to this challenging task, we explored the capability of the Reactive Spray Deposition Technology (RSDT) to deposit precious metal nanoclusters directly onto all surfaces in the volume of the sintered titanium material [2]. The studied metal coating of interest is Gold (Au). In this work, we have deposited Au coatings of various thicknesses onto the Ti-PTLs by using both EB-PVD and RSDT techniques. The Au thin film deposits are characterized by scanning electron microscopy (SEM), digital optical microscopy, inductively coupled plasma (ICP), and focused ion beam scanning electron microscopy (FIB-SEM) [2]. The optimal deposition parameters for thin and continuous Au films with precisely controlled thicknesses have been identified. In addition, the depth of penetration of the deposits in the volume of the PTL as a function of the deposition parameters have been studied in detail, and the results will be reported at the ECS 242 meeting.

Investigations on RuO2–In2O3 nanostructured porous composite thin films for benzene detection

Oxygen vacancies, oxidation and chemisorbed oxygen quantities will play a significant role in gas sensing properties of metal oxide semiconductors. Therefore, a suitable and effective method to improve the chemisorbed oxygen on the material surface is well needed to enhance the gas sensing performance. In the present investigations, mesoporous In2O3 and RuO2–In2O3 nanocomposite porous structured thin films with different RuO2 concentrations are prepared using the spray pyrolysis technique with optimized deposition parameters. Addition of RuO2 into In2O3 increases the chemisorbed oxygen on the surface of thin films. The prepared nanocomposite thin films' structural information, micromorphology, specific surface area and porosity are characterized by XRD, FESEM, AFM, TEM, UV–vis spectrophotometry, photoluminescence, XPS and BET. The enhancement of high specific surface area and porosity of RuO2–In2O3 nanocomposite thin films is favourable to gas sensing properties. The In2O3, RuO2–In2O3 nanocomposite thin films possessed highly selective, excellent response and recovery characteristics, and low detection limit towards benzene at room temperature. Among all the samples, RuO2–In2O3 nanocomposite thin film with a concentration of 20 wt% of RuO2 has shown remarkable sensing properties towards 50 ppm of benzene at room temperature.

Pulsed Lased Deposition of Single-Crystalline (001) Oriented Pb(Zr0.5T0.5)O3 Thin Film on PrScO3 Substrate

High quality thin films are important for domain engineering applications such as on-volatile memory applications. Single crystalline (001) oriented Pb (Zr0.5T0.5)O3 thin films have been grown by pulsed laser deposition on PrScO3 with strontium ruthenate (SRO) electrodes. Thin films were prepared from PZT ceramic targets with 15% excess PbO to compensate for lead loss at high deposition temperature. Layer by layer/step flow growth mode observed on AFM images has been realised by using a single terminated PrScO3 substrate as well as optimized deposition parameters. XRD measurements have confirmed the highly (001) oriented tetragonal symmetry. Furthermore, analysis conducted using piezoresponse force microscopy has shown that the thin films are monodomain with spontaneous ferroelectric polarization preferentially pointing upwards, i.e., away from the substrate. The absence of ferroelastic domains and the observed single ferroelectric domain structure are the results of both relatively small compressive misfit strain as well as favourable electrical boundary conditions.
 Keywords: PZT; Pulsed Laser Deposition; Epitax; Thin film

Review and preliminary design of 3-D printed ABS polymer torsion element with parametric internal structures

Various components utilized in the automobile dashboard controls are manufactured from plastic by a conventional molding process. With the recent trend and continuously changing designs of the components due to frequently upgraded models, the conventional process of manufacture of these components proves costly owing to the high investment in molds. The technology which has taken attention for these demanding conditions is the Fused Deposition or 3-D printing technology in development and manufacture of plastic components for ready use direct assembly which bypasses the process of mold manufacture and then subsequent plastic molding which is many times involves a considerable amount of production time and high production cost. The strength of the components produced by the 3-D printing method is seen to be greatly influenced by the infill density, print quality, and layer thickness.The depositing parameters have been studied in various studies but they failed to characterize the geometrical arrangement permutations through the addition of internal support structures to enhance the torsion strength of the components. The paper discusses a review of research work over the years proposes the first stage design and analysis of the plain component using Ansys workbench and also the manufacturing of these plain elements with various permutations of infill density, layer thickness, and print quality. The components thus produced will be tested and compared for optimal deposition parameters. By considering the gathered data, an optimization model that realizes the material usage, build time, strength characteristics, and their related variables will be presented and used to assist the components with optimal deposition parameters which will be further considered for design with internal support structures with the incorporation of varied parametric internal structure matrix.

One-step electrodeposition and fractal analysis of a novel Ni-graphene superhydrophobic coating

A novel superhydrophobic Ni-graphene coating was synthesized by one-step electrodeposition without low surface energy modification. The two-dimensional and three-dimensional morphology were investigated by scanning electron microscope, atomic force microscope, and confocal profilometry. Combining fractal theory and power spectral density analysis, the structural characteristics of the coating surface were quantified by key surface parameters. By building the numerical relationship between surface structure and wetting property, the coating-water contact mode was identified according to the measured contact angle and fractal contact angles calculated from Cassie and Wenzel theories. Additionally, the optimized deposition parameters and the role of graphene on the coating structure were also pinpointed. The results show that the Ni-graphene coating deposited at graphene oxide concentration of 0.20 g·L−1 and deposition current density of 40 mA·cm−2 exhibited dual-level fractal structure in micro- and nano-scales. The Ni-graphene superhydrophobic coating possessed a water contact angle of 156.1° ± 0.6°, a sliding angle of 6.2° ± 0.8°, as well as self-cleaning characteristics, and the wetting system was confirmed to follow the Cassie contact mode.

Medium-Entropy Nitride ZrNbMo-W-N Nanofilm-Based Substrate-Independent Selective Solar Absorber by a Cosputtering Method

Harvesting solar energy across the broad spectrum yet suppressing radiative heat loss in the infrared region has essential implications for solar-thermal applications. Multicomponent alloy nitride nanofilms are a promising class of materials that boost the solar-thermal conversion efficiency. Here, we build up a medium-entropy nitride ZrNbMo-W-N nanofilm-based selective solar absorber (SSA) by a cosputtering method. By fully studying the optical properties of single-layer ZrNbMo-W-N films, the optimized absorber with a trilayer structure achieves a significant boost in the optical performance, that is, an exceptional solar absorptance of 95.2% and a low emittance of 18.7% (400 °C), as well as angle-insensitive absorption. Moreover, the medium-entropy nitride-based absorber also enables remarkable structural and optical robustness, which retains a sound absorptance of 93.8% and a suppressed thermal emittance of 10.3% after annealing at 400 °C for 168 h, promising great potential for medium- and low-temperature applications. More significantly, our designed SSA can be easily fabricated on various substrates using optimized deposition parameters. In particular, the absorber is well deposited on a flexible cotton substrate, showing excellent solar absorption. It is believed that the combination of a multicomponent strategy and a cosputtering method, which can further modulate optical properties by suitably tailoring the elemental content and species, paves an effective way to investigate this kind of state-of-the-art solar-thermal materials.

A Path to Significant Reduction of the Interfacial Contact Resistance of Sintered Titanium Porous Transport Layers in Advanced Proton Exchange Membrane Water Electrolyzers

Proton exchange membrane water electrolyzers (PEMWEs) are a leading industry solution to large scale production of green hydrogen, and as a form of energy storage [5]. The PEMWEs have the advantages of having greater energy efficiency, higher product purity, and are environmentally friendly. Within the construction of a PEMWE stack, there are many catalysts coated membranes (CCMs) sandwiched between anode porous transport layers (PTLs) and cathode Gas Diffusion Layers. The PTL is constructed of sintered titanium powder or fibers. The Ti-PTL is on the anode side of a PEMWE cell where the water diffuses towards the CCM. The anode half-cell reaction or oxygen evolution reaction (OER) occurs on this side of the cell. This is important as the PTL is in contact with the bipolar plate (BPP) and the anode catalyst layer [9].A key aspect plaguing the PEMWEs is the highly oxidative and corrosive environment that is typically observed on the anode side. This significantly affects the interfacial contact resistance (ICR) of the components as the corrosion can cause the ohmic resistance of the PTL to increase. In order to combat the corrosion in the PTLs, in this work we use two thin film deposition methods, Physical Vapor Deposition (PVD) and Vacuum Sputtering, to deposit protective metal layers on top of the state-of-the-art Ti PTLs [2]. The explored metal coatings of interest are Platinum (Pt) and Gold (Au) [9]. For the purposes of these experiments, Au and Pt coatings with various thicknesses are deposited on Ti-PTLs by using either PVD or vacuum spattering method. As deposited thin films are characterized by scanning electron microscopy (SEM), digital optical microscopy, and inductively coupled plasma (ICP) analysis. Also, the in-plane conductivity and the ICR of all samples of interest are measured before and after the electrochemical tests by using the 4-probe method and in-house build setup for ICR measurements. The optimal deposition parameters for fabrication of thin, continuous and smooth Pt and Au protective coatings that result in minimum ICR and improved in-plane conductivity of the PTLs of interest are identified, and the results will be reported at the ECS 241 meeting.

Characterization of microstructure and mechanical properties of titanium -based bioactive ceramics laser-deposited on titanium alloy

Titanium-Based Bioactive Ceramics (TBBC), obtained by laser deposition of Ti and hydroxyapatite (HAp) powders, are the preferred materials for the clinical application of mandibular implants which are beneficial for bone tissue regeneration. So far, the bonding strength of TBBC fabricated by traditional additive manufacturing techniques reported in literature is no more than 35 MPa. Therefore, the main problem that restricts the application of this material on the mandible is the low bonding strength with the matrix. Unfortunately, the effective method to improve the bonding strength of TBBC is rarely mentioned. Under this circumstance, TBBC fabricated on artificial mandible are prone to peeling off during the bite and chew. In order to improve the mechanical properties of materials without losing the biological activity, this paper firstly studied the interaction mechanism between laser beam and Ti-HAp mixed powders. Afterward, two major crack avoidance factors, dilution rate and overlap rate, were analyzed to determine the optimal laser deposition parameters for TBBC. Finally, the mechanical performances were comprehensively studied. Of course, the biological activity of the TBBC was also preliminarily evaluated in Simulated Body Fluid (SBF). The results show that the fabricated TBBC have a bonding strength of 177.3–338.6 MPa, at least 5 times higher than the traditional process of 35 MPa. Furthermore, the increase of the maximum mass ratio of HAp powders to 15% will generate the bio-phase of Ca3(PO4)2, which provides a better Ca/P environment with PO43− needed for bone tissue regeneration.

Intensification of catalytic reaction of nitrous oxide decomposition into a replaceable wall-coated microreactor using electrophoretic deposition method

The novel replaceable wall-coated micro-reactor has been introduced to eliminate the hazardous nitrous oxide by utilizing the direct catalytic decomposition method. The commercial Pd/ γ-Al2O3 catalyst (containing 0.5 wt.% Pd) is coated on SUS304 stainless steel microchannels walls by using electrophoretic deposition (EPD) and then investigated at the temperature range of 300-400 °C. The main scope of this study is to define the optimum parameters affecting EPD such as deposition time, electrophoretic voltage, and solvent as the suspension media to reach the complete decomposition of nitrous oxide. The catalytic activity of the coated microchannels is verified at various gas hourly space velocities (GHSV). The nitrous oxide decomposition is enhanced 300% by raising the deposition time from 1 minute to 3 minutes and then remarkably is declined 80% at times higher than 3 minutes. The optimum electrophoretic deposition parameters including deposition time of 3 minutes at the voltage of 120 V in the range of 30-160 V and isopropanol as the solvent, resulting in 100% decomposition of nitrous oxide at 400 °C and GHSV of 1000 mL h−1 g−1cat . Moreover, the performance of the wall-coated micro-reactor at optimum EPD conditions compared to the equivalent packed-bed reactor caused 40% improvement in nitrous oxide decomposition and its energy consumption is 33.3% lower than packed-bed reactor for equal N2O decomposition.

Fabrication of enriched 170Yb2O3 thin targets for studying asymmetric fission in sub-lead mass region

Owing to the highly oxidizing and chemically active nature of rare-earth elements, preparation of isotopically enriched thin targets of rare-earth metals has been a challenging task. The successful fabrication of thin films of enriched 170Yb2O3 on carbon backing with areal density in the range 160–200 μg/cm2 and approximately 22μg/cm2, respectively is described here along with the various challenges encountered during the fabrication and new optimized operational parameters. On account of limited availability and high cost of the enriched 170Yb due to its extremely low natural abundance, many iterations were attempted with natural ytterbium to optimize the evaporation setup and its associated parameters. The electron beam physical vapour deposition technique in ultra-high vacuum facility was found suitable for the evaporation and a specially designed cylindrical tantalum crucible was used to further improve the collection efficiency. Optimization trials were carried out with the deposition parameters reported in the literature but a considerably high concentration of tantalum was noticed in the films. This impurity could drastically contaminate the experimental data and needed to be minimized. The present work reports a new set of deposition parameters optimized for the fabrication of thin ytterbium oxide films with the tantalum contamination reduced to indiscernible amounts. The final evaporation of enriched 170Yb2O3 was carried out with a 30 mg of the material that was found to be fully consumed. Various characterization techniques were carried out to ascertain thinness, purity and the elemental composition of the films viz. Rutherford Backscattering Spectroscopy (RBS) and Energy Dispersive X-ray Spectroscopy (EDS). These measurements corroborated the achieved optimization of deposition parameters with negligible contribution of impurities in the films. The purity and stability of the films were further established with a good quality of data obtained after irradiation with 28Si beam.

Insights into Cu2O thin film absorber via pulsed laser deposition

Cuprous oxide materials are of growing interest for optoelectronic devices and were produced by several chemical and physical methods. Here, we report on the structural, optical, and electrical properties of CuxO thin films prepared by the pulsed laser deposition technique. The substrate temperature, as well as the oxygen partial pressure in the deposition chamber, were varied to monitor the copper to oxygen ratio within the deposited films. The growth conditions were carefully optimized to provide the highest conductivity and mobility. Thus, 100 nm thick cuprous oxide films (Cu2O) deposited at 750 °C exhibited a resistivity of 16 Ω∙cm, high mobility of 30 cm2/(V∙s), and a bandgap of around 2 eV. The film deposited at the optimized deposition parameters on Nb:STO (001) substrate with Au top electrode showed a photovoltaic response with an open circuit voltage of 0.56 V. These results path the way to efficient solar cells made with Cu2O films via the pulsed laser deposition technique.

Kaolinite Thin Films Grown by Pulsed Laser Deposition and Matrix Assisted Pulsed Laser Evaporation.

In this work, thin films of lamellar clays were deposited by laser techniques (matrix assisted pulsed laser evaporation (MAPLE) and pulsed laser deposition (PLD)). The focus of this paper is the optimization of deposition parameters for the production of highly oriented crystalline films. The films were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and scanning electron microscopy (SEM). Contact angle measurements were employed to identify the wetting properties of the deposited thin films. Hydrophobic to superhydrophilic films can be prepared by using different deposition techniques and deposition parameters. MAPLE led to superhydrophilic films with contact angles in the range 4°–8°, depending on the microstructure and surface roughness at micro and nano scale. The 1064 nm PLD had a high deposition rate and produced a textured film while at λ = 193 nm an extremely thin and amorphous layer was depicted. Oriented kaolinite films were obtained by MAPLE even at 5 wt.% kaolinite in the target.

Preparation and infrared properties of Ni3Al–Cr3C2 composite films deposited by electrohydrodynamic atomization technology

The purpose of this work is to provide a clean and efficient preparation process for Ni3Al–Cr3C2 composite films. In this work, two kinds of slurries were prepared to deposit Ni3Al–Cr3C2 composite films on a 316L stainless steel substrate by electrohydrodynamic atomization (EHDA) technology. The slurry used for deposition was prepared with magnetic stirring and ball milling, respectively. The influence of the atomization parameters (atomization distance, operating voltage, and flow rates) on the characteristics of deposited films was investigated. Homogenous and compact films, with a structure of ∼10 layers, were fabricated under the optimized deposition parameters. The composition and micro-morphology of the composite films were examined. The spectral reflectivity of the Ni3Al–Cr3C2 composite films was characterized by the Fourier transforms infrared spectroscopy (FTIR) to study the infrared properties of the composite films. The results showed that because the slurries used to deposit the composite films were prepared by various methods, the infrared reflectivity and emissivity of the two composite films were different in the middle and far-infrared region. However, in the whole middle and far-infrared spectrum, the emissivity of the two films was significantly low. Therefore, the Ni3Al–Cr3C2 composite films deposited by EHDA are expected to be used in mid-high temperature solar films.

Influence of substrate temperature and oxygen pressure on the structural and optical properties of polycrystalline BaTiO3 thin films grown by PLD

The effect of substrate temperature and oxygen pressure on linear and nonlinear optical properties of pulsed laser deposited barium titanate BaTiO3 (BTO) thin films is reported in the present manuscript. BTO thin films have been deposited on n-type Si (100) and quartz substrates in the range of substrate temperatures from 400 to 700 °C and oxygen pressures from 0.005 to 1 mbar. The root means square (RMS) surface roughness is observed to decrease with the rise in substrate temperature and increased with an increase in oxygen pressure. The optimum background pressure and the substrate temperature are observed to be around ∼0.1 mbar and 700 °C, respectively. All the BTO thin films are found to be in the preferential (110) plane, from X-ray Diffraction (XRD), indicating the pseudocubic phase. Raman analysis also confirms the pseudocubic phase of BTO for all the thin films. The crystallite size, measured from XRD analysis is found to be increased with the increase in substrate temperature and is also affected by the background oxygen pressure. The thickness, linear absorption coefficient, and refractive index of the thin films are determined from UV–Visible–NIR spectroscopy. Transmission is observed to be 75–85% for all the thin films in the spectral range of 400–2000 nm. Nonlinear optical properties (NLO) are studied by an in-house assembled modified Z-scan set-up using continuous-wave (cw) Ar-Ion laser (λ = 488 nm) and found to be (57.54 ± 0.05) cm/W at the optimum deposition parameters.

Fabrication of AlGaN High Frequency Bulk Acoustic Resonator by Reactive RF Magnetron Co-sputtering System.

In this study, aluminum gallium nitride (AlGaN) thin films are used as the piezoelectric layers to fabricate solidly mounted resonators (SMR) for high frequency acoustic wave devices. AlGaN film is deposited on a Bragg reflector, composed of three pairs of Mo and SiO2 films, through a reactive radio frequency (RF) magnetron co-sputtering system at room temperature. The optimized deposition parameters of AlGaN film have a sputtering power of 175 W for Al target, sputtering power of 25 W for GaN target, N2 flow ratio (N2/Ar + N2) of 60%, and sputtering pressure of 10 mTorr. The obtained AlGaN film has a smooth surface, uniform crystal grains, and strong c-axis orientation. The contents of Al and Ga in the AlGaN film, analyzed by energy dispersive X-ray spectroscopy (EDS) are 81% and 19%, respectively. Finally, the frequency response s11 of the obtained SMR device shows that the center frequency is 3.60 GHz, the return loss is about −8.62 dB, the electromechanical coupling coefficient (kt2) is 2.33%, the quality factor (Q) value is 96.93 and the figure of merit (FoM) value is 2.26.