Substrate Distance Research Articles

Influence of organic promoter gradient on the MoS2 growth dynamics.

Chemical vapor deposition has been demonstrated to be the most efficient, versatile and reliable technique for the synthesis of monolayers of transition metal dichalcogenides. The use of organic promoters during the growth process was a turning point in order to increase the monolayer lateral size or to obtain complete coverage of the growth substrate. In this work we clarify the influence of the promoter gradient on the growth dynamics of MoS2. In particular, we place a sacrificial substrate covered with a promoter (a low sublimation-temperature perylene-based compound) downstream with respect to the growth substrate in order to maximize its gradient on the growth substrate through upstream diffusion. We demonstrate that the morphology and the number of layers of MoS2 are drastically affected by the distance of the growth substrate from the promoter sacrificial substrate. The farthermost area from the promoter substrate presents micrometric MoS2 triangular monolayers and large low hierarchy dendritic multi-layer structures. On the contrary the closest area reveals an almost continuous polycrystalline MoS2 monolayer, with bilayer terraces, with a lateral dimension up to hundreds of micrometers.

High Deposition Rate of Dual-cathode DC Unbalanced Magnetron Sputtering

Dual-cathode dc unbalanced magnetron sputtering for the deposition of ternary compound films with a high deposition rate was designed and constructed. It consists of two magnetrons of opposite magnetic polarities. Each magnetron consists of central and outer ring magnets with the residual inductions of 500 and 600 mT, respectively. The testing results of the system showed that high plasma volume could be created at a long substrate distance of about 15 cm from the targets. In addition, by using this sputtering system for coating TiAlN film, the result showed that at a target to substrate distance of 13 cm the film growth rate was 7.3 nm/min. It indicates that the sputtering system developed in this study is suitable for large substrate area coating due to the long distance of target to substrate.

Preparation and characterization of copper zinc tin sulfide-selenide thin films using a single target RF sputtering method

Copper zinc tin sulfide-selenide (CZTSSe) thin films have been prepared from a single alloyed CZTSSe target using one-step RF plasma magnetron sputtering technique. The films morphology, stoichiometry and crystalline properties have been examined as a function of the target to substrate distance, the deposition power and the substrate type. It was found that; within the range of the investigated target to substrate distance; better film crystallization was achieved when this distance equals to the target diameter, namely 5 cm in this work. An appropriate film thickness of 1.1 μm along with a more adequate compositional ratio equals to 14% Cu, 14% Zn, 16% Sn and 56% (S+Se) were obtained at low deposition power of 30 W with gradually decreasing the power during the deposition process. In this case, the low deposition rate resulted in proper compositional ratio, but the film crystallinity was found to be affected by the substrate type. As such, it was found that the use of a crystalline silicon substrate instead of the amorphous Soda Lime Glass substrate enhanced the film crystallinity.

Investigation on metallurgical, tribological, hardness properties of spray deposited and warm rolled Al-18Pb, Al-22Pb alloys

Al-18Pb and Al-22Pb alloys were processed by a rapid solidification process known as the spray deposition technique. Gaussian or bell-shaped deposits were obtained at a pressure of 10 bar, nozzle to substrate distance of 423 mm and substrate inclination angle of 0°. Deposits obtained from both alloys were warm rolled at a recrystallization temperature of 395 °C. Microstructural analysis of deposits showed that Pb is equally distributed in the Al matrix with 60% thickness reduction. For both alloys, the decrease in thickness percentage resulted in the decrease of hardness values. Porosity was lower in spray deposits of Al-18Pb alloy than the corresponding one from Al-22Pb alloy due to the casting and rolling defects. When the Pb percentage is increased from 18 to 22 in Al-22Pb compared with Al-18Pb, the wear rate increases abnormally. The frequency of wear and coefficient of friction values of Al-22Pb alloy were also higher when compared with those of Al-18Pb alloy.

Fabrication of the gold (Au) backed [formula omitted] targets for in-beam gamma-ray spectroscopy

The isotopically enriched T130e targets of ~ 1.2 mg/cm2 thickness were fabricated on 4–6 mg/cm2 gold (Au) backing. The vapor deposition method was employed using the resistive heating technique. To minimize the material consumption and increase the deposition efficiency, an indigenously developed graphite crucible with 1 mm opening was used to deposit T130e metal powder at a minimum source to substrate distance of 2 cm. A heat shield was placed at 1 cm above the graphite crucible to dissipate the heat. The fabrication of these targets were successfully achieved by using 10 mg of metal powder in each evaporation. The fabricated targets were characterized by using X-ray Fluorescence (XRF) measurements, Energy Dispersive X-ray Spectroscopy (EDS) and Scanning Electron Microscope (SEM). An experiment to study the nuclear structure via in-beam γ-ray spectroscopy was preformed using one of the fabricated T130e targets. The T130e(B9e,xn) reaction was used to populate the intermediate and high-spin states of Ba isotopes with B9e beam at 36- and 48 MeV lab energy. The relative percentage (%) cross-sections were measured for the B134−136a nuclei and found to be in agreement with the PACE4 calculations.

Landing maneuvers of houseflies on vertical and inverted surfaces.

Landing maneuvers of flies are complex behaviors which can be conceptually decomposed into sequences of modular actions, including body-deceleration, leg-extension, and body rotations. These behavioral ‘modules’ must be coordinated to ensure well-controlled landing. The composite nature of these behaviors induces kinematic variability, making it difficult to identify the central rules that govern landing. Many previous studies have relied on tethered preparations to study landing behaviors, but tethering induces experimental artefacts by forcing some behaviors to operate in open-feedback control loop while others remain closed-loop. On the other hand, it is harder for the experimenter to control the stimuli experienced by freely-flying insects. One approach towards understanding general mechanisms of landing is to determine the common elements of their kinematics on surfaces of different orientations. We conducted a series of experiments in which the houseflies, Musca domestica, were lured to land on vertical (wall landings) or inverted (ceiling landings) substrates, while their flight was recorded with multiple high-speed cameras. We observed that, in both cases, well-controlled landings occurred when the distance at which flies initiated deceleration was proportional to flight velocity component in the direction of substrate. The ratio of substrate distance and velocity at onset of deceleration (tau) was conserved, despite substantial differences in mechanics of vertical vs. ceiling landings. When these conditions were not satisfied, their landing performance was compromised, causing their heads to collide into the substrate. Unlike body-deceleration, leg-extension in flies was independent of substrate distance or approach velocity. Thus, the robust reflexive visual initiation of deceleration is independent of substrate orientation, and combines with a more variable initiation of leg-extension which depends on surface orientation. Together, these combinations of behaviors enable flies to land in a versatile manner on substrates of various orientations.

Distribution, habitat profile and genetic variability of Namibian succulent Lithops ruschiorum

Background: The species-rich flora of southern Africa comprises a high number of endemics, including succulents such as the flowering stones in the genus Lithops, but conservation status for these species is not well underpinned because detailed field data and assessments of genetic diversity are lacking.Objectives: We wanted to assess plant abundance and identify factors that may affect survival in Lithops ruschiorum through carefully conducted field surveys, and to determine amount and partitioning of genetic variation by amplified fragment length polymorphism (AFLP) analysis.Method: Field surveys were carried out in nine populations in Namibia. The most meticulously studied population was divided into 51 sites, while another 43 sites were recognised in the remaining eight populations. At each site, occupied area and number of plants were recorded as well as altitude, aspect, slope, soil texture and substrate. Amplified fragment length polymorphism markers were employed to study 52 individuals from seven populations.Results: In total, 8465 individuals were recorded. Plant density and/or plant number was associated with aspect, slope, soil texture, substrate and geographic distance from the coast. Analysis of molecular variation showed that 95% of the variability occurs within populations. Genetic and geographic distances among populations were correlated suggesting an isolation-by-distance pattern.Conclusion: Results are concordant with a strong impact of fog-based precipitation on plant density in the coastal populations, whereas rain probably is more important at one population which is situated further inland. Within-population genetic variation was medium high as usually reported for perennial, outcrossing species, but the low population differentiation implies considerable gene flow and/or population fragmentation.

Substrate temperature effect on the structural and photoluminescence properties of (Y-Gd)3Al5O12:Ce3+ thin films prepared by pulsed laser deposition

Thin films of (Y-Gd)3Al5O12:Ce3+ phosphor was laser ablated on Si (100) substrates by pulsed laser deposition (PLD) method. The deposition was done under 2.7 × 10−2 mbar oxygen atmosphere and 4.5 cm target to substrate distance using 266 nm Nd:YAG laser. The effect of growth temperature on the structural, photoluminescence and optical properties is explored by x-ray diffraction (XRD), scanning electron microscopy (SEM) and UV–visible spectroscopy, respectively. X-ray diffraction results show that the films crystallized in the cubic crystal structure with the crystallites’ size varying non-uniformly with the growth temperature. SEM images show non-compacted surface morphology comprising of spherical micro size particles for Ts = 100 °C and on increasing the substrate temperature, smooth surface morphologies were observed with the appearance of grain growth at 700 °C. Chemical composition analysis by the EDX method confirms the presence of Y, Gd, Al, O and Ce elements in the films, with estimated percentage atomic weight observed to depend on the growth temperature. Photoluminescence (PL) spectra show, broad band emission in the greenish yellow region attributed to the 5d to 4f electronic transitions of Ce3+. With increasing substrate temperature, a shift in PL emission to longer wavelength accompanied by changes in PL intensity was observed. Film deposited at 500 °C gave the highest PL intensity, in close agreement with the improved crystallinity from the XRD results at this temperature. UV-Vis analysis shows the films depicting high reflectance and low absorption above the visible and near infrared regions, with diffuse reflectance which depends on the growth temperature.

Effect of Microstructure Control of Thin Film Yttria Stabilized Zirconia Electrolyte for Solid Oxide Fuel Cells by Adjusting Oblique Angle and Target Substrate Distance of Sputtering Process

In the present study, thin film yttria stabilized zirconia (YSZ) electrolyte was fabricated for solid oxide fuel cells via radio frequency (RF) magnetron sputtering with variation in oblique angle and target substrate distance (TSD). Growth tendencies were differentiated through adjusted oblique angle and TSD during sputtering, thereby microstructure of YSZ was changed. Electrochemical behavior of microstructure-controlled thin film YSZ was investigated by means of applying YSZ to anodic alumina oxide (AAO) based solid oxide fuel cells (SOFC). On nanoporous AAO substrates, Pt anode, YSZ electrolyte, and Pt cathode were deposited serially all through sputtering. For depositing thin film YSZ electrolyte, oblique angle and TSD were differentiated into four cases each, while thickness was set to be equal. YSZ thin films were evaluated using FESEM, AFM, FIB-SEM, XRD, and XPS. Electrochemical performance was investigated through i-V plot and EIS.

Microstructural and optical properties of Ni-doped ZnO thin films prepared by chemical spray pyrolysis technique

In this study, multifunctional ZnO and Ni-doped ZnO thin films were prepared by chemical spray pyrolysis technique (SPT) on soda lime glass substrates at 300 °C. The liquid precursors for the films were synthesized from high purity zinc acetate (Zn (CH3COO)2.2H2O) and nickel acetate (Ni (CH3COO)2.3H2O). In order to vary the concentrations of the metallic constituents in the films, the precursors were prepared at 0.1 M, 0.15 M, 0.2 M and 0.25 M in distilled water. For the Ni-doped ZnO thin films, the mixing ratio of the precursor was in proportion of nickel acetate 0% to 10% by volume of the zinc acetate. Meanwhile, deposition parameters i.e. temperature, substrate distance and deposition time were optimized to achieve good quality thin films. Rutherford Backscattering spectroscopy (RBS) result shows an increase in oxygen content in ZnO film with 84% compared to Ni–ZnO thin films. The thickness of ZnO was observed to be lower than Ni–ZnO thin films, however a marginal increase in the thickness of Ni–ZnO thin film was observed with increase in Ni2+ content. Visual observation and spectrophotometer results indicated that the films are highly transparent in the UV-visible region. Ni–ZnO films were observed to have a higher transmittance than ZnO thin films, with increase in transmittance with Ni2+concentrations. The absorption edge of ZnO was observed to be lower than Ni–ZnO, and the optical band gap of undoped ZnO thin film decreased slightly from 3.28 eV to 3.20 eV of 10% Ni-doped ZnO thin film.

Energy flux measurements on an atmospheric pressure surface barrier discharge

Energy flux measurements by a passive thermal probe were performed for a diffuse coplanar surface barrier discharge to determine the transfered energy to a substrate in dependence on the substrate distance to the electrode and working gas of the discharge. The largest energy flux was found at ∼300–400 m above the electrode surface to be about 900 mW cm−2. Furthermore, an active substrate cooling mechanism could be identified within the plasma caused by gas convection flows for very small distances. Variation of the working gas (argon, molecular gas) indicates the importance of the gas and surface reactivity for the transferred energy to the substrate. Molecular gases result in a remarkably higher energy flux compared to rare gas.

An investigation on titanium doping in reduced graphene oxide by RF magnetron sputtering for dye-sensitized solar cells

A study investigating the effects of titanium (Ti) atoms sputtered from different sources on substrate distance was attempted in order to effectively dope a reduced graphene oxide (rGO) thin film surface. Factors such as crystallinity, morphology, phase formation, light absorption, and surface chemical state of rGO-TiO2 were investigated. As a result, functional groups or chemical states revealed the presence of Ti-O-C in rGO-TiO2 nanocomposite after the sputtering process. The titanium source from the target was of Ti3+ species as determined using X-ray photoelectron spectroscopy (XPS). It was found that average sized Ti3+ ions of around 59.4 nm were incorporated into the rGO nanosheet. A customized Dye-Sensitized Solar Cells (DSSCs) device was fabricated with the photo-anode consisting of sputtered rGO-TiO2 nanocomposite. After optimization, the Ti target allocated with 10 cm-apart FTO glass-coated rGO nanosheet and 0.67 cm2 active area exhibited an ideal PCE of 6.60%, which is remarkably higher than the usual 5 cm sputtering distance the sample (1.90%) had achieved.

Structural and physical properties of NbO2 and Nb2O5 thin films prepared by magnetron sputtering

NbOx thin films have been deposited on silicon (100) and quartz substrates by magnetron sputtering using a metallic Nb target in an optimized argon–oxygen atmosphere. This work investigates the dependence of structure–property relations on the key deposition parameters towards establishing optimum deposition conditions for the growth of NbOx polycrystalline films. It is found that a sputtering condition corresponding to DC power density 9.87 W cm−2, a substrate temperature of 720 °C, low gas pressures of 8 mtorr, a target to substrate distance of 45 mm gives thin films with good homogeneity and a high degree of crystallinity in the case of both NbO2 and Nb2O5. X-ray diffraction (XRD) and Raman spectroscopy confirmed the tetragonal phase of NbO2 and orthorhombic phase of Nb2O5 for similar deposition temperatures. Scanning electron microscopy (SEM) observations indicate that NbO2 has a unique nanoslice structure while Nb2O5 has a flake-like structure. The optical transmittance of the films has been investigated and found to be dependent on the oxygen gas content during deposition; the optical transmittance decreases with increasing O2 gas content. Optical constants of the films were calculated by fitting a suitable thin film transmittance model to experimental transmittance spectra using a modified Swanepoel technique. The nanohardness and stress in the films were measured by nanoindentation and an optical profilometer respectively. Nanohardness and stress in the film show no large dependence on the oxygen gas content except at high oxygen gas content. The nanohardness value of NbO2 films is approximately 6 GPa, and the Young’s modulus is 150 GPa. The Nb2O5 films exhibit a nanohardness of 5.8–13 GPa and a Young’s modulus of 137–161 GPa.

TRIBOLOGICAL PROPERTIES OF Al2O3 + TiO2 COATINGS MANUFACTURED BY PLASMA SPRAYING

In the paper the results of tribological, microscopic, and mechanical research of Al2O3 + TiO2 coatings manufactured by plasma spraying are presented. The feeding material was a powder Al2O3 + 13 wt.% TiO2 (Metco 6221, OerlikonMetco) with grain size – 45 ± 15 μm. The cylinder substrates made from stainless steel (X5CrNi18-10) had a diameter equal to 25 mm and 2 mm of thickness. The variable spray parameters were plasma torch velocity in terms of substrate and spray distance. The morphology of obtained coatings was tested by scanning electron microscope (SEM), and the microstructure was investigated by light optical microscopy (LOM) and SEM. The results of mechanical properties examinations revealed the dependence of the microhardness and fracture toughness on the spray parameters. Tribological examinations were made in the ball-on-disc mode in technical dry friction conditions. Two loads were used, 5 N and 10 N. Based on the carried out tests, it could be concluded that a shorter spray distance and a reduction of the torch velocity allows one to achieve a more compact structure, which is characterized by good adhesion at the coating-substrate interface (in range from 11 to 14 MPa) and good wear resistance.

RETRACTED ARTICLE: Effect of target to substrate distance on the material properties of the Y2SiO5:Ce3+ thin film by pulsed laser deposition

The effect of the target–substrate distance on the structural, morphological and photoluminescence (PL) properties of the thin film of the Y2SiO5:Ce3+ commercial phosphor studied by the pulsed laser deposition method. The distance between the target and the substrate was in the order of 4.0–6.0 cm with a variation of 0.5. X-ray powder diffraction analysis (XRD) shows that the average crystal size is about 37 nm. As the substrate distance is increased, a substantial reduction in film thickness observed from the measurement of mass before and after deposition. This attributes to the semicircular diffusion of the plasma plume due to the reduction of particle species flow over the deposition area of the substrate. The main PL emission peak was observed at 438 nm, which is attributed to the 5d → 4f transition in Ce3+ orbitals. The 5d orbital is the first excited state in Ce3+ ion energy levels with two close states of 2D3/2 and 2D5/2. The splitting of 5d into suborbital 2D3/2 and 2D5/2 is due to the electron transition between orbitals of the trivalent cerium ion and the host material. This is studied using three excitation wavelengths (276, 303 and 356 nm) in which all their corresponding emission is in the same region peaked at 438 nm. The highest emission occurs with an excitation wavelength of 356 nm for all substrate distances. The CIE gives the blue emission band for the emission wavelength of 438 nm. The maximum ultraviolet–visible spectrum absorbance was observed at around 356 nm. The scanning electron microscope images show that the sizes and the morphology change as the substrate distance changes. The energy-dispersive X-ray spectrometer shows the presence of all the elements of the compound matrix (Y, Si, O and Ce).

Formation of carbon nanowalls by pulsed filtered cathodic vacuum arc deposition

In the present study, Carbon Nanowalls (CNWs) were produced by Pulsed Filtered Cathodic Vacuum Arc Deposition (PFCVAD) on glass substrates. A high purity graphite rod was used as a cathode target. Growth was performed by varying the distance between the target and substrate, namely 1 cm (1A250), 2 cm (2A250) and 3 cm (3A250). No CNW formation has been observed on the substrate, when the target and substrate distance is 3 cm. Amorphous nature of carbon structures has been shown with the Raman measurements. Raman mapping has been also performed to show the vertical wall structures of the CNWs. Surface morphology of the CNWs was investigated by Atomic Force Microscopy (AFM) and Scanning Electron Microscopy (SEM) measurements. It has been found that the wall widths are roughly 1.8 μm and 1.0 μm for the samples 1A250 and 2A250, respectively. It has also shown that curvier vertical wall structures have formed for samples 2A250 compared to that of 1A250. X-ray Photoelectron Spectroscopy measurements have shown that 40% sp3 CC bonding and CO bonding which indicates the amorphous nature of the structure. Optical studies have shown that CNWs have low reflectance in visible region when the substrate to target distance is 1 cm which makes this thin coating very suitable for dark coating applications.

Microstructure and Oxidation Behavior of Metal V Films Deposited by Magnetron Sputtering.

Direct-current magnetron sputtering (DCMS) was applied to prepare vanadium (V) films on Si substrate. The influence of substrate temperature (Ts) and target–substrate distance (Dt–s) on phase structure and surface morphology of V films were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscope (AFM) and transmission electron microscopy (TEM). The results show that the crystallinity of the V films increases with increasing Ts and decreasing Dt–s. The film deposited at Ts = 400 °C and Dt–s = 60 mm exhibits the best crystallinity and <111> preferred orientation with a regular tetrahedral surface morphology. Oxidation behavior of the V thin films has also been studied by X-ray photoelectron spectroscopy (XPS).

Spatial and social conditions for the location of agricultural biogas plants in Poland (case study)

Biogas production in Poland is controversial. There is a lot of interest in the construction of installations of various scale, and protests of local communities take place at the same time. Residents do not agree to the construction of biogas plants due to the fear of nuisance related to its functioning. This work is a case study of the area of Kamionka – the rural commune in Poland, in terms of the possibility of locating an agricultural biogas plant. The main sources of substrates for biogas production in the commune were determined. When selecting the appropriate location for an agricultural biogas plant, the focus was on the areas designated in the “Study of conditions and directions for spatial development” as areas with the approval of locating devices generating energy from renewable sources. These properties were analyzed in terms of substrate availability (which are waste from animal production, fruit pomace, waste from processing, biomass of plants grown intentionally), plot size, infrastructure status and distance from protected areas. On this basis, one location was chosen that meets all those criteria. Surveys have shown that residents are afraid of unpleasant smell, noise, emerging waste and explosion risk. Nevertheless, the majority of respondents declared willingness to cooperate with the biogas plant.

Scratch Resistance of Flexible Carbon Fiber‐Reinforced Polymer Composites Improved by Atmospheric Pressure Plasma Polymerized‐Organosilicon Oxide Films

An improvement on the scratch resistance of flexible carbon fiber‐reinforced polymer composites (FCFRPCs) has been undertaken by deposition of organosilicon oxide (SiOxCy) films. The SiOxCy films are synthesized using a low temperature‐atmospheric pressure‐plasma polymerization method with an atmospheric pressure plasma jet (APPJ) at various substrate distances. SiOxCy thin films are rapidly deposited onto FCFRPCs at a short exposed‐duration of 150 s with an APPJ. The precursor tetramethyldisiloxan (TMDSO) vapors are mixed with air gases, injected into the air plasma jet of APPJ, and sprayed onto FCFRPCs at room temperature (~23°C) at atmospheric pressure. The scratch resistance of FCFRPCs is meaningfully improved from an overpowering occurrence of scratching (100%) on as‐received FCFRPC to an overall absence of scratching (0%) on SiOxCy film deposited FCFRPC against the steel wool for up to 62 cycles at a 100 g loading. The enhanced scratch resistance of FCFRPCs by APPJ‐synthesized SiOxCy films is strongly dependent on the increased nanoindentation hardness (of up to 1.60 GPa), the increased surface hardness (of up to 7H), and the decreased surface roughness (of up to 6.5 nm for the roughness of the standard deviation from the height mean Rms and 2.5 nm for the roughness of the mean deviation from the height mean Ra), respectively. How the critical films characteristics affect the increased surface hardness and the decreased surface roughness for APPJ‐synthesized SiOxCy films are discussed. POLYM. COMPOS., 40:E1893–E1902, 2019. © 2018 Society of Plastics Engineers

Deposition Pressure Dependent Electric Properties of (Hf, Zr)O2 Thin Films Made by RF Sputtering Deposition Method

To study the applications for ferroelectric non-volatile memory and ferroelectric memristor, etc., deposition pressure dependent electric the properties of (Hf, Zr)O2 thin films by RF sputtering deposition method were investigated. The bottom electrode was TiN thin film to produce stress effect on the formation of orthorhombic phase and top electrode was Pt thin film by DC sputtering deposition. Deposition pressure was varied along with the same other deposition conditions, for example, sputtering power, target to substrate distance, post-annealing temperature, annealing gas, annealing time, etc. The structural and electric properties of the above thin films were investigated. As a result, it is confirmed that the electric properties of the (Hf, Zr)O2 thin films depend on the deposition pressure which affects structural properties of the thin films, such as, structural phase, ratio of the constituents, etc.