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Owing to the energy-efficient attributes of electrochromic technology, there has been a growing emphasis on the fabrication of electrochromic devices with high-contrast and stable performance. As an electron donor, the deliberate incorporation of oxygen vacancies into an electrochromic material is poised to significantly elevate the film's electrochromic characteristics. In this study, we successfully synthesized one-dimensional W 18 O 49 nanowires thin films with enhanced oxygen vacancies using a straightforward combination of solvothermal reactions and annealing in Ar. In comparison to films annealed in air, those treated in argon (Ar) exhibited a higher concentration of oxygen vacancies, resulting in improved light absorption characteristics. The optimal annealing conditions were determined to be 400 °C for 40 min. Under these conditions, the thin film demonstrates enhanced electrochromic performance, exhibiting a notable 71.6% modulation in transmittance, a 27.2% increase compared to the air condition. It displays a rapid response time (T b = 3.3 s, T c = 3 s), high coloration efficiency (CE = 55.9 cm2 C−1), and excellent cycling stability (with a ΔT retention rate of 93.9% after 750 cycles). [ABSTRACT FROM AUTHOR]

Within the framework of the model of the nonlocal thermoelastic peak of low-energy ion, the formation of intrinsic stress in a carbon coating deposited from the vacuum arc plasma in the argon atmosphere is theoretically studied. It is shown that the flow of particles bombarding the deposited coating contains, along with C+ ions, also Ar+ ions involved in the formation of intrinsic stress in the coating. The flux density of Ar+ ions resulting from ionization losses of C+ ions passing through the argon atmosphere is proportional to both the flux density of C+ ions and the density (pressure) of argon. Expressions are obtained for the intrinsic stress in the deposited carbon coating depending on the bias potential on the substrate and the argon pressure for the cases of both constant and pulsed potentials. The analysis of the obtained expressions shows that the intrinsic stress in the carbon coating decrease with increasing argon pressure.

(Zn1-x-yAlxBy)O (x = 0, y = 0, x = 0.02 and y = 0.005, 0.01, 0.02) ceramics have been synthesised via conventional solid-state reaction (SSR) method. Each ceramic formed as a single phase with a dense microstructure. The Seebeck coefficient, power factor, and electrical resistivities were determined for all these ceramics. Very interesting changes have been observed in the thermoelectric properties of ZnO ceramics sintered in the atmosphere of argon gas at 1450 °C via Al and B codoping. The power factor ~6.332 × 10 −4 W K − 2 m−1 and Seebeck's coefficient ~ −89.85 µ V K −1 along with lowest electrical resistivity ~ 1.224 m Ω cm at 700.0 °C was obtained for the composition with y = 0.01, i.e., (Zn0.097Al0.02B0.01)O. [ABSTRACT FROM AUTHOR]

Abstract Alumina ceramics with different sintering temperatures in argon atmosphere were obtained using stereolithography-based 3D printing. The effects of sintering temperature on microstructure and physical and mechanical properties were investigated. The results show that the average particle size, shrinkage, bulk density, crystallite size, flexural strength, Vickers hardness, and nanoindentation hardness increased with the increase in sintering temperature, whereas the open porosity decreased with increasing sintering temperature. No change was observed in phase composition, chemical bond, atomic ratio, and surface roughness. For the sintered samples, the shrinkage in Z direction is much greater than that in X or Y direction. The optimum sintering temperature in argon atmosphere is 1350 °C with a shrinkage of 3.0%, 3.2%, and 5.5% in X, Y, and Z directions, respectively, flexural strength of 26.7 MPa, Vickers hardness of 198.5 HV, nanoindentation hardness of 33.1 GPa, bulk density of 2.5 g/cm3, and open porosity of 33.8%. The optimum sintering temperature was 70 °C higher than that sintering in air atmosphere when achieved the similar properties.

This paper presents an experimental and numerical research on super lean premixed H 2 – O 2 flames under argon atmosphere in a combustion bomb with constant volume, and applied CHEMKIN to perform simulation for the flames. The high-speed schlieren photography is employed to record the development process of expanding spherical flame, and laminar burning velocities of super lean premixed H 2 – O 2 – Ar flames with different back pressures under argon atmosphere are calculated, and the influence of equivalence ratio and initial pressure on flame instability is analyzed, and the mass burning fluxes are calculated by simulation and flame structure and rate of elementary reactions is analyzed. The results show that, with equivalence ratio decrease, laminar flame velocity and mass burning flux will decline; with initial pressure increase, laminar flame speed will decline and mass burning flux will increase. For flame stability, when initial pressure rises, the hydrodynamic instability on hydrogen flame surface is enhanced, more easily resulting in cellular instability. As pressure rises, Lewis number and density ratio under each pressure will approximate to constant values, therefore, flame thickness is the main factor influencing flame instability when initial pressure rises. When equivalence ratio decreases, unequal diffusion instability often occurs easily under leaner conditions during flame development. According to simulation results, the laminar flame velocity is the result of interaction between the chain branching reaction and the chain termination reaction and the changes of equivalence ratio will affect above two reactions. For flame structure, the results show that when equivalence ratio is small, chemical reaction velocity of hydrogen gas burning will decline and reaction zone will enlarge, besides, H and OH concentration will also decline. As equivalence ratio decreases, the maximum H mole fraction constantly declines, which is consistent with the changing trend of laminar flame velocity with equivalence ratio. • Laminar burning velocities of H 2 – O 2 - Ar at super lean conditions were studied. • Flame stability was affected by initial pressure and ϕ in Ar. • The trend of the H mole fraction with ϕ is consistent with the trend of U u in Ar. • When the H 2 / O 2 mixture gets lean, the reaction rates of R1 - R4 will decrease in Ar. [ABSTRACT FROM AUTHOR]

Zn 0. 9 Se:Co 0. 1 thin films were deposited on sapphire (Al2O3) substrates in argon atmosphere at various gas pressures by pulsed laser deposition. Influence of argon pressure on the thickness, surface morphology, crystal structure and optical properties of the thin films were investigated by various diagnosis tools. It was found that these physical properties were correlated to the argon pressure and appeared like a mutation between the pressure of 2 Pa and 4 Pa. As the deposition pressure changed from 2 Pa to 4 Pa, the collision probability between ablated species and argon molecule was increased, which resulted in the transformation of the deposition type from sputter effect to adsorption effect and the mutation of film thickness and structure. These in turn influence the transmission range and band gap of the films. All of the results suggest that the ambient pressure is a very important factor to the deposition of Zn 0. 9 Se:Co 0. 1 films by PLD. [ABSTRACT FROM AUTHOR]

Abstract Composition in (Zn 0.98-y In y) (y = 0.05, 0.02, 0.01, 0.005) were fabricated via conventional solid-state sintering route under an argon atmosphere at 1400 °C for 10 h (h) their phases, microstructures and thermoelectrical properties were investigated. Single phase ceramics were formed for the composition with y ≤ 0.05. The highest power factor (PF) of 481.8 µW K−2 m−1 ± 0.2, Seebeck coefficient −98.08 µV K−1 ± 0.2 and electrical resistivity (ρ) of 1.997 mΩ cm ± 0.2 was obtained for x = 0.02, y = 0.005 i.e., (Zn 0.975 Al 0.02 In 0.005)O. It is studied that PF is a function of lattice parameter c/a ratio. The resistivities of all the compositions were tuned. These tuned resistivities will be helpful for future thermoelectric devices. [ABSTRACT FROM AUTHOR]

High-speed imaging and schlieren imaging were used to investigate the interaction of the laser beam with the powder bed at pressures up to 5 bar, in argon and helium atmospheres. The entrainment of powder particles in the flow of shielding gas generated by the laser plume, and hence denudation, was reduced at high pressure for both gases. However, for argon, high pressure increased the temperature of both the melt pool and the laser plume, which significantly increased the generation of spatter and ionisation of the metal vapour with degraded surface smoothness and continuity. For helium, the formation of spatter and plasma did not increase with the increase in pressure above that observed at atmospheric pressure: its higher thermal conductivity and thermal diffusivity limited the laser plume temperature. Layers built at 5 bar in helium had a surface smoothness and continuity comparable to those built in argon at atmospheric pressure, but achieved at a higher laser scan speed, suggesting that a high-pressure helium atmosphere may be used to enhance the build rate. [ABSTRACT FROM AUTHOR]

In this paper, Ca 6 BaP 4 O 17 :Sm 3+ and Li + co-doped Ca 6 BaP 4 O 17 :Sm 3+ phosphors were synthesized in air and argon atmospheres using a solid-state reaction method. The phosphor morphologies and crystal structure were studied using scanning electron microscopy and X-ray diffraction, respectively. The emission and absorption characteristics were investigated using photoluminescence emission spectroscopy and diffuse reflectance spectroscopy. The surface states and composition of phosphor were investigated using X-ray photoelectron spectroscopy. The emission integrated intensities of the phosphors sintered in an argon atmosphere increased 3.5 fold than the ones sintered in air atmosphere, with Li + ions becoming embedded in the lattice of the Ca 6 BaP 4 O 17 :Sm 3+ phosphor. This occurs because there are fewer defect/oxygen vacancies and less of the secondary phase forms, leading to better Sm 3+ emission. The results suggest that sintering a mixture of the raw materials of a phosphor in an argon atmosphere is a good approach for synthesizing Ca 6 BaP 4 O 17 :Sm 3+ phosphor powders. The color purity and CIE values of an optimized phosphor sample sintered in an argon atmosphere with an Li + ion compensator were calculated to be ~ 99.6% and (0.612,0.386) in the orange–red region under 405-nm excitation, respectively. Moreover, the solid solubility of Sm 3+ ions in the Ca 6 BaP 4 O 17 host can be enhanced by using an argon atmosphere in the synthesis process. [ABSTRACT FROM AUTHOR]

In this study, the surface chemistry, skeleton structure and thermal safety of three different methylsilyl modified silica aerogels (SAs) have been explored under heat treatment in an argon atmosphere. With the heat treatment temperature increasing to 700 °C, the secondary particles aggregate, the silica skeletons get denser and the pore volumes diminish. Meanwhile, the excellent thermal insulation performance is still maintained, with the thermal conductivity not exceeding 30 mW⋅ m −1⋅ k −1. It finds the Si-(CH 3) 3 groups are converted to Si-(CH 3) 2 groups, and further transformed to Si-CH 3 groups. The generated and original Si-CH 3 groups can be maintained until 700 °C, which constitutes the chemical basis for the high-temperature hydrophobicity. The improved thermal stability and reduced gross calorific values both verify that the thermal safety of the heat-treated SAs has been obviously enhanced. This study provides an engineering reference for the high-temperature thermal insulation application for hydrophobic SAs. [ABSTRACT FROM AUTHOR]

The volatile organic compounds (VOCs) in the packing of chicken meat in a modified atmosphere was qualitatively and quantitatively evaluated. The total number of 72 samples of chicken hindquarters were stored under two different modified atmospheres (70% O2, 30% CO2, and 70% argon, 30% CO2) for 20 days. Analyses were performed on Days 0, 4, 8, 12, 16, and 20. VOCs in the headspace samples were detected and quantified by gas chromatography/mass spectrometry (GC/MS) every fourth day of storage. Pentamethylheptane, dimethylsulphide, dimethyl disulphide, dimethyl trisulphide, dimethyl tetrasulphide, hydrogen sulphide and ammonia were detected. Pentamethylheptane and ammonia had similar values for both modified atmospheres (MA). The other compounds were found only in argon MA from the Day 16 of storage with a subsequent increase of values. The measured values for dimethylsulphide were 10.7 and 13.8 mg/l, for dimethyl disulphide they were 1.9 and 10.7 mg/l, dimethyl trisulphide levels were 15.7 and 19.3 mg/l and dimethyl tetrasulphide levels were 93.2 and 418.3 mg/l for Day 16 and 20. The hydrogen sulphide level was detected from 80 to 370 mg/l after the 8th day of storage. We showed that the argon MA is less suitable for packaging raw chicken parts than the oxygen MA in view of the increased amount of microflora and unpleasant odour as assessed by sensory analysis. Oxygen prolonged the shelf life by about four days in comparison with argon. Sensory evaluation was similar for both atmospheres after air exhaustion. The argon MA did not extend the shelf life as compared to the oxygen MA.

The present study aims to understand non-isothermal reduction behavior of nanocrystalline NiO powder in undiluted CH 4 and Ar atmospheres by thermal analysis, mass measurement and XRD techniques. Low Ni content observed in the oxide powder was attributed to the moisture and OH groups which were removed upon heating to 625 K above which reduction of NiO to Ni took place in both atmospheres. Under Ar flow, the oxide powder was slightly reduced to Ni as temperature increased to 1300 K. In CH 4 atmosphere, the oxide reduction was followed by C deposition with increasing temperature. Complete reduction of NiO to Ni was attained at ~ 1000 K owing to H 2 formed by CH 4 pyrolysis. It was observed that nickel particles were sintered into pellets with a size of ~ 2 μm at 1100 K under CH 4 flow. At 1200 and 1300 K, Ni had finer particles with sizes < 200 nm and gained mass in consequence of C deposition. [ABSTRACT FROM AUTHOR]

In previous works under open atmosphere at various temperatures KBr host crystal never accepted paramagnetic Mn 2+ ion in its lattice, but KH 2 PO 4 host crystal accepted VO 2+ ion in its lattice where K + ion substituted with VO 2+ . In a series of works using high-pressure reactor at various pressures and temperatures under different gas atmospheres, Mn 2+ ion was inserted in KBr host, and VO 2+ ion was inserted in KH 2 PO 4 host in sites different from those observed in previous works. The best results were obtained for Mn 2+ doped KBr at pressure of 100 bars and 50 °C under Argon atmosphere, and for VO 2+ doped KH 2 PO 4 at pressure of 100 bars and temperature of 50 °C under oxygen atmosphere. The structural parameters of paramagnetic species formed were determined by EPR spectroscopy and optical transitions were determined by UV–Vis spectroscopy. [ABSTRACT FROM AUTHOR]

Novel heterocyclic phosphoramidates were synthesized by a nucleophilic substitution reaction of 2-substitutedbenzimidazoles and diphenyl chlorophosphate (ClPO3Ph2) in the presence of potassium hydroxide (KOH) under an argon atmosphere. The structures of the phosphoramidates were characterized by NMR, IR, melting point, and elemental analysis. [ABSTRACT FROM PUBLISHER]

The present work focuses on the influence of SiC content on the morphology and microstructure of in-situ synthesized ZrB 2 –SiC composite using ZrO 2 , B 4 C and Si via a single-step reduction process under argon atmosphere. The ZrB 2 –SiC composite was synthesized with variation in mole content of starting reactant and calcination temperature. The molar ratio of ZrO 2 :B 4 C:Si was increased from 2:1.5:0.5 to 2:1.67:1.34 at 1300–1500 °C, resulting SiC content increased and average grain size reduced. Major phase of ZrB 2 and SiC were detected in the composite using XRD and XPS techniques. Morphology and microstructure of synthesized ZrB 2 and SiC were determined by SEM and TEM analysis. The results revealed that a homogenous layer of uniformly dispersed SiC particles was exhibited over the surface of rod and spherical granulation of ZrB 2 , which restricted the grain growth of ZrB 2 particles during synthesis. With increasing the SiC content, the pinning effect on the grain boundary enhanced the dense structure of ZrB 2 –SiC composite. The feasibility of reaction for the synthesis of ZrB 2 –SiC composite was confirmed by thermodynamic calculation and experimental results. It can be concluded from experimental results that the composite was synthesized below the thermodynamically calculated synthesis temperature due to maintaining moderate vacuum backfilled by argon. • Present work is aimed to study the influence of SiC content on the morphology and microstructure of in-situ synthesized ZrB 2 –SiC composite using ZrO 2 , B 4 C and Si via a single-step reduction process under argon atmosphere. • The impurity-free dense ZrB2–SiC composite is synthesized using a different molar ratio of starting reactant at a lower calcination temperature. • The tiny SiC particle was homogeneously distributed on the ZrB2 particles, which restricted its grain growth and provided a dense ZrB2–SiC composite. • With increasing the SiC content up to an optimum limit, oxide-free ZrB 2 –SiC composite was obtained along with the pinning effect on the grain boundary enhancing the dense structure of the ZrB 2 –SiC composite. [ABSTRACT FROM AUTHOR]

Eu3+-doped zirconia has been considered an efficient phosphor material due to its multi-colour emissive photoluminescence properties. Tuning of emission colour is possible by changing the Eu3+-ions concentration and excitation wavelength. The influence of Eu3+-ions and excitation wavelength on the emission intensity, asymmetric ratio, CIE coordinates, and Judd-Ofelt parameters of the Eu3+-doped zirconia nanophosphors have been explored in this work. Ultra-fine nano-sized particles of pure tetragonal zirconia were observed when the samples were calcined under an argon atmosphere at 800 °C. The expansion and distortion of tetragonal zirconia has been confirmed from XRD and Raman Spectra of Eu3+-doped zirconia samples, respectively. The XPS analysis suggested elemental composition and incorporation of trivalent state of Eu-ions in Eu3+-doped zirconia sample calcined under argon calcination condition. Further, emission spectra of Eu3+-doped zirconia samples have been investigated at the excitation wavelength of 240 nm, 393 nm, and 463 nm. The emission spectra of 3 mol % and 6 mol % Eu3+-doped zirconia samples revealed several emission peaks in the range of 580–710 nm corresponding to the Eu3+-ions transition of 5D 0 → 7F j (=0 to 4). However, due to lower emission intensity, these transitions were not clearly visible up to 1 mol % Eu3+-ions. The CIE coordinates confirmed the tuning of emission colour in Eu3+-doped zirconia nanophosphor at different excitation wavelengths. The Judd-Ofelt parameters also suggested that the Eu3+-doped zirconia may be utilized for better optical gain. So, nano-sized Eu3+-doped zirconia phosphor materials may consider as a potential candidate for different luminescence applications. [Display omitted] • Eu3+-doped t-ZrO 2 nanoparticles have been prepared under Ar calcination atmosphere. • XRD and Raman suggest lattice expansion and distortion of t-ZrO 2 , respectively. • Emission of 3 and 6 mol% Eu3+-doped ZrO 2 varied with excitation wavelengths. • Asymmetric ratio and CIE coordinates suggest tuning of emission via different λ ex. [ABSTRACT FROM AUTHOR]

The volatile organic compounds (VOCs) in the packing of chicken meat in a modified atmosphere was qualitatively and quantitatively evaluated. The total number of 72 samples of chicken hindquarters were stored under two different modified atmospheres (70% O2, 30% CO2, and 70% argon, 30% CO2) for 20 days. Analyses were performed on Days 0, 4, 8, 12, 16, and 20. VOCs in the headspace samples were detected and quantified by gas chromatography/mass spectrometry (GC/MS) every fourth day of storage. Pentamethylheptane, dimethylsulphide, dimethyl disulphide, dimethyl trisulphide, dimethyl tetrasulphide, hydrogen sulphide and ammonia were detected. Pentamethylheptane and ammonia had similar values for both modified atmospheres (MA). The other compounds were found only in argon MA from the Day 16 of storage with a subsequent increase of values. The measured values for dimethylsulphide were 10.7 and 13.8 mg/l, for dimethyl disulphide they were 1.9 and 10.7 mg/l, dimethyl trisulphide levels were 15.7 and 19.3 mg/l and dimethyl tetrasulphide levels were 93.2 and 418.3 mg/l for Day 16 and 20. The hydrogen sulphide level was detected from 80 to 370 mg/l after the 8th day of storage. We showed that the argon MA is less suitable for packaging raw chicken parts than the oxygen MA in view of the increased amount of microflora and unpleasant odour as assessed by sensory analysis. Oxygen prolonged the shelf life by about four days in comparison with argon. Sensory evaluation was similar for both atmospheres after air exhaustion. The argon MA did not extend the shelf life as compared to the oxygen MA. [ABSTRACT FROM AUTHOR]

Abstract: The effect of argon atmosphere on the formation of MoSi2 by self-propagating combustion method has been detailedly investigated in present work by comparing SHS reaction between Mo and Si in argon atmosphere with that in vacuum. The SHS procedure in argon atmosphere could produce higher heating rate and maximum temperature than that in vacuum. The particle size distribution of synthesized products has been studied by light transmission sedimentation method. More homogeneous particle size distribution of the molybdenum disilicide by SHS method in argon atmosphere was achieved than it in vacuum. And it also can be observed in SEM photographs of synthesized products. Compared with SHS method in vacuum, a purer product was indicated by XRD and X-fluorescence analysis results while reaction in argon atmosphere. [Copyright &y& Elsevier]

Abstract: Wear rates and coefficients of friction (COF) of an Al–18.5wt.% Si alloy (A390) were measured in dry air and argon environments at different test loads using a block-on-ring (SAE 52100 type steel) configuration. The wear rates of the A390/52100 steel pair tested in argon were always lower compared to those measured in dry air with 5% RH. The difference was especially significant at low loads: a 10-fold reduction in the magnitude of the wear rates occurred at 10N. Similarly, the tests performed in argon resulted in lower steady-state COF values of 0.29±0.02 compared to 0.57±0.08 measured in air. Progression of the sliding wear process in A390 tested in an argon atmosphere was studied as a function of the sliding distance: the process initiated with the formation of iron-rich transfer films on the surfaces of the exposed Si particles. During sliding the composition of the layers changed. Aluminum-rich tribolayers were formed during the steady-state wear at long sliding distances. These layers were compacted and provided continuous coverage of contact surfaces. In contrast, the surfaces of the samples tested in air were covered by iron-rich tribolayers that were oxidized and showed evidence for easy spallation. The depth of the damaged zone in the material underneath the tribolayers was smaller in the samples tested in argon compared to those tested in air, in which higher subsurface plastic strains were generated during sliding wear. Wear tests were also performed in air (5% RH) on A390 samples put in sliding contact against graphitic diamond-like carbon (DLC) coatings. The DLC coating prevented direct contact between the steel counterface and the A390 that resulted formation of worn surface morphologies that were free of iron-rich oxidized tribolayers. The corresponding wear rates and COF values were lower than those obtained for the A390/52100 steel pair tested in argon, e.g., a wear rate of 9.26×10−6 mm3/m and a steady-state COF value of 0.24±0.02 were attained against the DLC coatings at 10N. [Copyright &y& Elsevier]

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When spraying is conducted at ambient atmosphere, the entrainment of air cools the plasma jet and affects its expansion. It can also cause oxidation or chemical decomposition of the sprayed materials. Inert plasma spraying (IPS), generally conducted in an argon atmosphere, prevents these phenomena. However, the main drawbacks of IPS in comparison with air plasma spraying are the capital and operating costs. This paper presents a study in which nitrogen is used as a substitute for conventional argon atmosphere, thus reducing costs by 25 to 30%. Titanium carbide and niobium powders were sprayed in both argon and nitrogen atmospheres. Cryogenic cooling of the substrate was used during the spray process. This helps to maintain a low temperature in the chamber, produce thick coatings, and allows the use of substrate materials that are sensitive to heat. The velocity, temperature, and composition fields of the argon-hydrogen plasma jet flowing in argon or nitrogen at atmospheric pressure are compared from numerical simulation. The adhesion, roughness, and microstructure of the niobium and TiC coatings produced in both atmospheres are discussed as well as their nitrogen content. [ABSTRACT FROM AUTHOR]

Debinding at different temperatures under an argon atmosphere, combined with sintering, was used to obtain alumina ceramics fabricated from stereolithography-based 3D printing. The effect of debinding temperature under an argon atmosphere on the microstructure, physical, and mechanical properties were investigated. The results showed that the alumina ceramics had a layered structure, and the interlayer spacing first increased and then decreased with the debinding temperature. Some carbon residue was observed when debinding was performed between 350 and 450 °C, and no residual carbon was observed when the debinding temperature was higher than 500 °C. The shrinkage in the Z direction was much greater than that of the X or Y directions due to layer-by-layer forming mode. There was a slight fluctuation in mechanical properties such as flexural strength (18.9–22.3 MPa), Vickers hardness (110.6–173.7 HV), and nano-indentation hardness (16.9–22.6 GPa). The optimal debinding temperature was 500 °C under an argon atmosphere, which displayed a shrinkage of 2.3% in the X direction, 1.9% in the Y direction, and 3.4% in the Z direction. At this temperature, the flexural strength of the ceramics was 22.3 MPa and the open porosity of the ceramics was 35.6%. • Fabrication of alumina ceramics via 3D printing technology. • Debinding in argon atmosphere to avoid deforming or cracking. • Control properties of ceramics to satisfy the application requirement of ceramic cores. [ABSTRACT FROM AUTHOR]