Focus Shots Research Articles

Self-Lubricating Pulsed Ion Beam-Assisted PTFE Coating of Titanium in Argon Discharge to Tailor Wear Resistance and Friction

Polytetrafluoroethylene (PTFE) ions were deposited on titanium substrate by using a 1.5 kJ Mather plasma focus device in argon, equipped with a PTFE source. The PTFE and argon ions generated during different number of shots of dense plasma focus (DPF) resulted in deposition of PTFE on the Ti surface. Prepared samples were characterized for structural properties, elemental composition, surface morphology, wear resistance and frictional behavior by X-ray diffraction, energy dispersive X-ray, scanning electron microscope and pin on disc test, respectively. The area of the coherent X-ray scattering region of PTFE coated on Ti estimated by XRD is 9 nm. Both XRD and SEM show that the area of the coherent X-ray scattering region increases with the increase in the number of focus shots. The EDX results confirmed that the concentration of carbon and fluorine on the Ti substrate increases with the increase in energy of ion flux. Finally, the pin on disc test confirms that PTFE ion plasma coating on the Ti surface reduces the friction up to 35% and enhances wear resistance of the Ti surface up to 89%. The above analysis reflects that PTFE coating shows remarkable tribological behavior with low value of friction coefficient and enhanced value of wear resistance. Moreover, this study provides an intuition for organizing the design of self-lubricating and effective wear-resistant coatings.

Deposition of molybdenum carbide thin films by dense plasma focus device

This work was motivated by the promising physiochemical properties and catalytic activity of molybdenum carbide. Thin films of molybdenum carbide were deposited on the mono-crystalline cubic Si (400) substrate by utilizing a 3.6 kJ dense plasma focus device (Mather-type) with multiple shots. The structure of the films was examined by X-ray diffraction (XRD). XRD results indicated the absence of crystalline film for 5 focus shots, while for increased numbers of focus shots, the emergence of Mo-C peaks in the orientations (120), (014) and (232) confirmed the formation of orthorhombic β-Mo2C polycrystalline films. Moreover, a small variation in the crystallite size was observed by increasing the number of focus shots. The presence of molybdenum and carbon was confirmed by energy-dispersive X-ray (EDX) analysis. Surface morphology was studied under scanning electron microscope (SEM). SEM micrographs revealed non-uniform films with some surface defects such as cracks and craters of micron size, and rough surface. Revealed by the ellipsometry technique, the film thickness increased by increasing the number of focus shots. The electric conductivity, measured by the four-point probe technique, was the highest for 10 focus shots. However, the films have some structural defects, low conductivity and impurities like silicon and silicon carbide, but it was the first ever successful attempt to deposit molybdenum-carbide (Mo2C) thin films using the dense plasma focus device.

Microstructure, fractal geometry and corrosion properties of CrN thin films: The effect of shot number and angular position

The effect of different plasma focus shots and angular positions (0° and 30°) on the properties of chromium nitride (CrN) coatings, deposited by a plasma focus (PF) device on stainless steel substrates, have been systematically investigated in this paper. The structural and morphological properties of CrN thin films were characterized by X-ray diffraction (XRD) and atomic force microscopy (AFM). Moreover, the corrosion behavior of the CrN thin films was investigated using the ‘c’ method. The XRD patterns demonstrated the growth of the polycrystalline structure composed of CrN/Cr2N nanograins and the enhanced crystallinity of the CrN coatings upon increasing the shot numbers. In addition, AFM results showed enhanced multifractal properties of the sample prepared at 0° angular position and a reducing trend in these properties for the layers prepared at 30° angular position. Moreover, they exhibited sharp hillock-like features on the surface, corresponding to the columnar growth of the CrN coatings, which further protruded as the number of shots increased. The results of the corrosion test showed that the resistance of stainless-steel substrate was improved by depositing the CrN coatings due to the formation of a passive and protective layer on its surface. Notably, ceramic CrN film, prepared through 10 shots at 30° angular position, showed the best corrosion resistance. Our strategy is advantageous for designing and manufacturing novel devices and instruments based on CrN corrosion resistant coating.

Corrosion resistance and surface microstructure of Mg3 N2 /SS thin films by plasma focus instrument.

Utilizing a plasma focus (PF) instrument, magnesium nitride (Mg3 N2 ) thin films were synthesized on stainless steel substrates. Twenty five optimum focus shots at 8 cm distance from the anode tip were used to deposit the films at different angular positions regarded to the anode axis. Scanning electron microscopy (SEM), atomic force microscopy (AFM), and X-ray diffraction (XRD) analyses were performed to assess the surface morphology and structural characteristics of Mg3 N2 films. Based on AFM images, these films were studied to understand the effect of angular position variation on their surfaces through morphological and fractal parameters. By increasing the angle, we verify that the grain size decreased from 130(0) nm to 75(5) nm and also the mean quadratic surface roughness of the films reduced in its average values from (28.97 ± 3.24) nm to (23.10 ± 1.34) nm. Power spectrum density analysis indicated that films become more self-affine at larger angles. Furthermore, the corrosion behavior of the films was investigated through a potentiodynamic polarization test in H2 SO4 solution. It was found that the ion energy and flux, varying with the angular positions from the anode tip, directly affected the nanostructured roughness and surface morphology of the samples. The electrochemical studies of films show that the uncoated sample presented the lowest corrosion resistance. The highest corrosion resistance was obtained for the sample deposited with 25 optimum shots and at 0° angular position reaching a reduction in the corrosion current density of almost 800 times compared to the pure stainless steel-304 substrate. HIGHLIGHTS: Mg3 N2 /SS films have been deposited at different angles by plasma focus (PF) instruments. The effect of angular position on the surface microtexture, morphological parameters, and corrosion features of the films was studied. The RBS measurement and X-ray diffraction are utilized to identify the crystalline phases and thickness of films.

The effect of neon ion irradiation on tungsten for next generation fusion reactor

Tungsten exhibits robust thermo-physical and mechanical properties in ion material interaction. It is considered as an important material of the plasma facing component for next generation fusion reactor. This material could be one of the candidates to use in the divertor region of the tokamak. With this motivation a series of experiments have been performed with a plasma focus device to study the effect of neon irradiation on tungsten in various experimental conditions like with angular variation and with number of plasma focus shots. Exposed and unirrdiated tungsten samples were analyzed subjecting to surface morphological and structural studies namely using optical microscope, scanning electron microscope, atomic force microscope, grazing incidence X-ray diffraction, Vickers hardness measurement. OM photographs are analyzed quantitatively in terms of holes and pores with angular variation and number of PF shots. Surface analyses verifies the formation of micro-cracks, bubbles, blisters, holes. X-ray diffraction pattern shows the development of compressive stress on the sample due to thermal load and formation of other phases or expanded phases.

Effects of Plasma Focus on Seed Germination and Seedling Growth of 14 Thai Rice Varieties

Thailand Plasma Focus 2 (TPF-2) is operated at 2.16 kJ of storage energy with argon as a filled gas and can emit sharp x-ray pulses to plant cells in nanosecond (10-9 s) duration. The effects of plasma focus x-ray on seed germination and seedling growth of 14 Thai rice varieties treated under 10 conditions; 0 (control), 2, 4, 6, 8, 10, 12, 14, 16, and 18 plasma focus shots, were investigated. The results show that the germination rates and growth reduction rates were significantly different among the rice varieties. The germination rate of 10 varieties (Jek Chuey, KDML105, LPT123, PTT1, RD41, RD47, RD49, RD67, RD79, and SPR2) decreased when treated with a high number of plasma focus shots. LD50 and GR50 values were calculated, except for KTH17, RD1, RD7, and RD31 whose germination only slightly decreased, or remained constant, even after they were treated by 18 plasma focus shots. HIGHLIGHTS Effects of plasma focus irradiation on germination and growth were assessed on 14 Thai rice varieties Shoot and root lengths of rice seedlings were measured 10 days after of plasma treatment Plasma focus was operated at 12 kV and the number of plasma focus shots was varied from 0 (control) to 18 shots Sensitivity to plasma irradiation was found to differ among rice seeds tested GRAPHICAL ABSTRACT

Characteristics of tungsten layer deposited on graphite substrate by a low energy plasma focus device at different angular position

Layers of tungsten were deposited on two types of graphite substrates at three different angular position by a low energy plasma focus device. First series of substrates included only raw graphite while carbon interlayers were used for the second type. Tungsten deposition process was carried out at 0°, 15°, and 30° angular location with respect to the device anode axis during 40 focus shots at optimum argon gas pressure. The characterization of the deposited tungsten coatings was verified by X-ray diffraction (XRD), scanning electron microscopy, energy-dispersive X-ray spectroscopy, Raman spectroscopy and Nanoindentation analyses. Tungsten-carbon structures such as WC1-X, W2C, WC, and W2(C, O) were detected by XRD analysis. Compounds such as WC1-X, W2C and W2(C, O) were identified on raw graphite substrate while WC1-X, WC, W2C were formed on the graphite substrates with carbon interlayer. For both types of samples positioned at 30 degrees with respect to device axis, the WC1-X phase, which is a high temperature structure with high melting point, was detected more than other tungsten-carbon structures. The coating of carbon interlayer on substrates changes surface morphologies and leads to homogenous deposition of tungsten layer on the surface. The increase in angular position of substrates led to creation of flat and smooth surfaces. Raman spectroscopy shows the presence of WO3 and amorphous carbon structures in both types of prepared samples. Nanoindentation analysis indicates that the hardness of samples increases after tungsten deposition process. The substrate angular position with respect to anode axis is an effective parameter in deposition process of tungsten layers.

Role of ion energy flux on the structural and morphological properties of silicon oxy-nitride composite films deposited by plasma focus device

ABSTRACTCrystalline silicon oxy-nitride (SiON) composite films are deposited on Si substrate for multiple (5, 15, 25 and 50) focus shots (FS) by plasma focus device. The X-rays diffraction patterns reveal the development of various diffraction peaks related to Si, Si3N4, and SiO2 phases which confirms the formation of SiON composite film. The intensity of Si3N4 (1 0 2) plane is linearly increased with the increase of FS. The Si3N4 (1 0 2) phase does not nucleate for 5 FS. Raman analysis confirms the formation of β–Si–N phase. Raman and Fourier transform infrared spectroscopy analysis reveals that the strength of chemical bonds like Si–N, Si–O formed during the deposition process of SiON composite films is associated with the bonds intensity which in turn depends on the number of FS. The field emission scanning electron microscopic analysis reveals that the surface morphology like size, shape and distribution of micro/nano-dimensional particles, film compactness and the formation of micro-rods, micro-teethes and micro-tubes of SiON composite films is entirely associated with the rise in substrate surface transient temperature which in turn depends on the increasing number of FS. The EDX spectrum confirms the presence of Si (22.5 ± 4.7 at. %), N (13.4 ± 4.5 at. %) and O (54.7 ± 11.3 at. %) in the SiON composite film. The thickness of SiON composite film deposited for 50 FS is found to ∼15.47 µm.

Effects of deposition angle on synthesis of amorphous carbon nitride thin films prepared by plasma focus device

Amorphous carbon nitride (a-CNx) thin films were deposited on graphite substrate at different angular positions using a low energy (up to 4.9 kJ) Mather-type plasma focus device. The deposition processes were carried out during 20 focus shots at optimum nitrogen gas pressure of 0.4 mbar. The formation of amorphous carbon nitride was confirmed by Raman Spectroscopy, SEM, EDX, FTIR, and XRD analyses. The intensity ratio of D and G peaks (ID/IG) recorded by Raman Spectroscopy showed two distinct trends at various angular positions. The sample deposited at 30° had the highest ID/IG ratio and correspondingly the highest sp3 CHx content in FTIR spectrum. Samples with lower ID/IG ratio appeared with smaller grain size and more smooth surfaces in SEM images. The highest CN intensities in FTIR spectrum belonged to those samples deposited at 30 and 75° angular positions.

DEMOCRATIC FILM AND THE AESTHETICS OF CHOICE

ABSTRACTBoth the Germans and their American occupiers understood that films were supposed to support a democratic culture and worldview during the occupation following the Second World War. This essay explores how democratic culture comes to be defined at mid‐century through choice, and how two films that played in the Western Zones, Der Apfel ist ab (1948) and The Best Years of Our Lives (1946), take up choice as a formal aesthetic closely tied to a fraught democratic experience. Best Years, praised by German critics as a realistic portrait of American life, also adopts what the film critic André Bazin calls a democratic and liberal film style of deep focus compositions and shots of long duration that allow the spectator to choose what to look at in the frame. Yet, as even Bazin notes, this choice is slyly coercive. Der Apfel was a critical failure and thematises indecision within the narrative. In contrast to Best Years, it turns the optics of choice into vertiginous confusion in which there are no good choices. This essay argues that the democratic refusal in Der Apfel ist ab is an apt critique of ‘democracy as choice’, and that the film opens up new horizons of political invention.

Effects of fusion relevant transient energetic radiation, plasma and thermal load on PLANSEE double forged tungsten samples in a low-energy plasma focus device

Tungsten is the leading candidate for plasma facing component (PFC) material for thermonuclear fusion reactors and various efforts are ongoing to evaluate its performance or response to intense fusion relevant radiation, plasma and thermal loads. This paper investigates the effects of hot dense decaying pinch plasma, highly energetic deuterium ions and fusion neutrons generated in a low-energy (3.0 kJ) plasma focus device on the structure, morphology and hardness of the PLANSEE double forged tungsten (W) samples surfaces. The tungsten samples were provided by Forschungszentrum Juelich (FZJ), Germany via International Atomic Energy Agency, Vienna, Austria. Tungsten samples were irradiated using different number of plasma focus (PF) shots (1, 5 and 10) at a fixed axial distance of 5 cm from the anode top and also at various distances from the top of the anode (5, 7, 9 and 11 cm) using fixed number (5) of plasma focus shots. The virgin tungsten sample had bcc structure (α-W phase). After PF irradiation, the XRD analysis showed (i) the presence of low intensity new diffraction peak corresponding to β-W phase at (211) crystalline plane indicating the partial structural phase transition in some of the samples, (ii) partial amorphization, and (iii) vacancy defects formation and compressive stress in irradiated tungsten samples. Field emission scanning electron microscopy showed the distinctive changes to non-uniform surface with nanometer sized particles and particle agglomerates along with large surface cracks at higher number of irradiation shots. X-ray photoelectron spectroscopy analysis demonstrated the reduction in relative tungsten oxide content and the increase in metallic tungsten after irradiation. Hardness of irradiated samples initially increased for one shot exposure due to reduction in tungsten oxide phase, but then decreased with increasing number of shots due to increasing concentration of defects. It is demonstrated that the plasma focus device provides appropriate intense fusion relevant pulses for testing the structural, morphological and mechanical changes on irradiated tungsten samples.

Influence of Nitrogen on Hydrogenated Amorphous Carbon Thin Films Deposited by Plasma Focus Device

To carry out our research, a plasma focus device is used to deposit thin films of nitrogen doped hydrogenated amorphous carbon (a-C:H:N) onto the stainless steel-AISI-304 substrates at room temperature. Thin films are deposited with the same numbers of focus shots, at the same distance from the anode tip and with different partial pressures of nitrogen in the mixtures of acetylene/nitrogen as working gas. The nitrogen contents of deposited films are studied using nuclear reaction analysis (NRA) techniques. The results prove that nitrogen contents of the samples do not increase significantly by increasing partial pressure of nitrogen of the working gas for both sets of the samples. Moreover, NRA results exhibit the limitation of nitrogen incorporated into the samples, when this experimental setup is used. G-peak position and peak intensity ratio of the D-band to G-band (ID/IG) are used to investigate the diamond characters. Also, they show that sp2 clustering is highly dependent on the nitrogen atomic contents and angular position of the samples. Scanning electron microscopy (SEM) shows the granular surface morphology of the films. Furthermore, it shows that angular position of the samples with respect to the anode axis plays an important role in the grain size of the surface of the samples. The thickness of the films decreases significantly by increasing angular position of the samples, while it decreases slightly by increasing partial pressure of nitrogen of the working gas. The Vickers surface hardness of the thin films exhibits significant dependency on the sp2 clustering.

Synthesis and characterization of magnesium aluminate (MgAl2O4) spinel (MAS) thin films

In a quest to identify more economic routes for synthesis of magnesium aluminate (MgAl2O4) spinel (MAS) thin films, dense plasma focus device was used with multiple plasma focus shots. Structural, bonding between composite films, surface morphological, compositional and hardness properties of MAS thin films were investigated by using x-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy dispersive x-rays (EDX) analysis and Vickers micro hardness test respectively. In XRD graph, the presence of MgAl2O4 diffraction peaks in crystallographic orientations (222), (400) and (622) pointed out the successful formation of polycrystalline thin films of MgAl2O4 with face centered cubic structure. The FTIR spectrums showed a major common transmittance band at 697.95 cm−1 which belongs to MgAl2O4. SEM micrographs illustrated a mesh type, granular and multi layers microstructures with significant melting effects. EDX spectrum confirmed the existence of magnesium, oxygen and aluminum in MAS films. A common increasing behavior in micro-hardness of composite MgAl2O4 films by increasing number of plasma focus shots was found.

Effect of annealing temperature on the structural, morphological, and mechanical properties of polycrystalline zirconium oxynitride composite films deposited by plasma focus device

In this article, we reveal the post deposition annealing effect on the structural, morphological, and mechanical properties of polycrystalline zirconium oxynitride (P-ZrON) composite films deposited for 40 focus shots using a plasma focus device. The development of Zr(101), ZrN(111), ZrN(200), Zr3N4(320), ZrN0.28(002), and m-ZrO2(200) diffraction peaks confirms the deposition of P-ZrON composite films. The peak intensity, crystallite size, dislocation density, compressive stress, and texture coefficient of the Zr3N4(320) plane and the microstructural features such as the shape, size and distribution of nanoparticles as well as the film compactness are influenced by the annealing temperature. Elemental analysis confirms the presence of Zr, N, and O in the deposited films. The microhardness of the P-ZrON composite film annealed at 500 °C is found to be 11.87 GPa which is 7.8 times that of virgin zirconium.

New perspective on nano-porous gallium nitride formation on p-type silicon with plasma focus device

ABSTRACTFor the first time, the formation of nano-porous (NP) gallium nitride (GaN) on p-type silicon (Si) (100) substrate with the plasma focus device was observed. Four and six main plasma focus shots with GaN as the target on the Si substrate were applied. Subsequently, two shots of nitrogen plasma without the GaN target were applied to both of the Si surfaces. Then the substrates were gone through a 1050°C nitrogen treatment by a thermal chemical vapor deposition (TCVD) device. Field emission scanning electron microscopy and atomic force microscopy indicated NP structures on the surface of the substrates. With the increase in the amount of shots, thicker and rougher NP structures were formed. Additionally, X-ray diffraction shows GaN polycrystalline formation on the surface with the energy-dispersive X-ray spectroscopy, indicating that there was nitrogen deficiency on the Si substrates.

Dense-plasma-driven ultrafast formation of FePt organization on silicon substrate

This article demonstrates the removal of organic capping and promotion of long-range 2D organization of chemically synthesized FePt nanoparticles dispersed on Si 〈100 〉 substrate by means of pulsed H+ energetic ion irradiation using a dense plasma focus (DPF) device. The irradiation of energetic H+ ions on FePt nanoparticles clearly resulted in enhanced structural and magnetic behaviour of the FePt nanoparticles as a function of plasma focused irradiation shots. Transmission electron microscopy (TEM)/scanning electron microscopy (SEM) images of the FePt nanoparticles clearly show a marked enhancement in average particle size from 2.5 nm for non-irradiated sample to about 28 nm for four plasma focus shots irradiation. The gradual removal of organic capping over chemically synthesized FePt nanoparticles with increasing plasma focus shots exposure is confirmed using Raman spectroscopy. A uniform 2D organization of bimetallic FePt nanoparticles over 1 cm × 1 cm silicon substrate is obtained with three plasma focus shots with better magnetic properties as compared with plasma-untreated FePt nanoparticles. Plasma focused irradiation shots

Topographical, structural and hardness changes in surface layer of stainless steel-AISI 304 irradiated by fusion-relevant high energy deuterium ions and neutrons in a low energy plasma focus device

This paper aims to investigate the effects of fusion relevant intense pulse of energetic and high fluence deuterium ions and neutrons generated in a low energy (3.0kJ) plasma focus device (UNU/ICTP PFF) on stainless steel-AISI 304 samples. The irradiation was performed using different number of deuterium plasma focus shots (1, 3, 5 and 10) at a fixed axial distance of 8cm from the anode tip. X-ray diffraction spectra of irradiated samples indicated the structural phase transition from mixed ferittic-austenitic form in virgin AISI 304 SS sample to only austenitic form indicated by the presence of only γ-Fe diffraction peaks and increase in corresponding peak intensities. A small shift in all austenitic diffraction peaks towards the higher diffraction angles was observed indicating the decrease in lattice spacing by vacancy defects most probably due to energetic fusion neutrons. Field emission scanning electron microscopy and atomic force microscopy images showed the formation of nanometer sized particles on irradiated samples' surfaces. The size of nanoparticles initially decreased as the number of focus shots was increased from 1 to 3 and to 5, and later as the number of focus shots was increased to 10, the aggregations of the particles occurred to form bigger clusters. The sample surface hardness was found to decrease with increasing number of irradiation shots which can be attributed to the induction of vacancy defects by 2.45MeV fusion neutron irradiations and the increasing deposition of the copper ablated from the anode-top on the irradiated samples. The study clearly established that the plasma focus device provides intense fusion relevant pulses suitable for causing the topographical, structural and hardness changes on the surface of the irradiated SS AISI 304 which is one of the candidate materials for plasma facing components in fusion reactors.

RETRACTED: Growth and characterization of GaN nanoparticles on P-type Si (100) substrate by plasma focus device with nitrogen plasma

A Mather type plasma focus device (PFD) was used to grow semiconductor material gallium nitride nanoparticles on P-type silicon (100) with nitrogen as working gas. Two, four and six amount of plasma focus shots were applied to 3 Silicon substrates, field emission scanning electron microscopy and atomic force microscopy indicated spherical gallium nitride nanoparticles nearly similar to gallium nitride quantum dots on the substrate that was deposited with two shots. Photoluminescence spectrometry shows emission peaks in violet 420 nm (2.95 eV) wavelength in all three samples, additionally as the shots increased small peaks at near ultraviolet 360 nm (3.44 eV) were observed. UV–Vis–NIR shows most reflectance at near ultraviolet for the second sample with four shots, as X-ray diffraction shows only some peaks for the third sample with six shots which indicates the low quality of gallium nitride crystalline formation.

Microstructure, Surface Morphology and Photoluminescence Properties of Al-Doped ZnO Thin Films Prepared by Plasma Focus Method

Al-doped ZnO (AZO), as one of the most promising transparent conducting oxide (TCO) materials, has now been widely utilized in thin film solar cells. In this research the optimization process of AZO thin films deposited by plasma focus device was carried out by investigation of its physical properties under different deposition conditions for its utilize as a front contact for the Cadmium Telluride (CdTe) based thin film solar cell applications. The effects of number of focus shots and angular position of substrate on the microstructure, surface morphology and photoluminescence properties of the thin films have been systematically studied. X-ray diffraction (XRD) study confirmed the polycrystalline nature of the all deposited AZO thin films. XRD analysis also revealed that crystal structure characteristics of obtained samples strongly depend on deposition conditions (number of shots and angular position). Scanning electron microscopy (SEM) and atomic force microscopy (AFM) analyses revealed the structure growth and enhancement of surface roughness, with increasing of focus shots or decreasing of angular position. From Photoluminescence (PL) emission spectra, the variations of structural defects and band gap energy for all the AZO thin films prepared under different deposition conditions were also discussed.

Characterization and hydrogen gas sensing performance of Al-doped ZnO thin films synthesized by low energy plasma focus device

Nanocrystalline Al-doped ZnO (AZO) thin films were deposited on glass substrates at room temperature by Mather-type plasma focus device using a ZnO target with an Al content of 3 wt%. The effect of number of focus shots on the microstructure, elemental composition, surface morphology and H2 gas sensor performance of AZO deposited thin films were investigated. X-ray diffraction (XRD) analysis confirmed the polycrystalline nature of the all deposited AZO thin films. XRD results also indicated strong dependence of crystallinity and crystallite size of deposited thin films on number of focus shots. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) analyses led to the conclusion that the size of grains/clusters on the surface of thin films and the surface roughness of deposited samples enhance with increasing of focus shots. The experiments and measurements involving the AZO deposited thin films towards hydrogen were carried out at different operating temperatures within 150–400 °C for various concentrations of hydrogen in air. The H2 sensing response enhanced with concentration and operating temperature, and reached its maximum at 300 °C–1000 ppm concentration of hydrogen gas. The results also indicated shorter response times for samples deposited with less focus shots.