Ar Environment Research Articles

Cr Doped MoS2 Films: Tribological Properties, Microstructure, and Electronic Structure

Abstract Cr doped MoS2 films were deposited by magnetron sputtering. The tribological properties of Cr doped MoS2 films under vacuum (VC) and air (AR) environments were investigated. The results show that Cr doped MoS2 film with Cr target power of 0.2 A (0.2 A Cr:MoS2 film) exhibits low friction coefficient and long wear life under both VC and AR environments. The chemical compositions of the films were analyzed by energy-dispersive X-ray spectroscopy (EDX) and X-ray photoelectron spectroscopy (XPS). With the increases of Cr target power, the content of Cr increases. The cross-sectional field emission scanning electron microscopy (FESEM) morphologies show that the structure of the films changed from granular particles to column when the Cr target power increases from 0.2 A to 0.4 A. The wear mechanism has also been discussed based on the characteristics of worn surface. The 0.4 A Cr:MoS2 film has the lowest wear volume among these films, which can be attributed to the compact microstructure. The bandgap of Cr doped MoS2 films were measured by XPS and the tribological performance of the film is found to be best when there is a modest bandgap. It can be speculated that the tribological performance of Cr doped MoS2 films are closely related to the width of bandgap.

Evolution of structural and magnetic properties of Ar2+ ion irradiated TiO2 thin films annealed under argon atmosphere

In this report, the evolution of structural as well as magnetic state of 900 °C annealed TiO2 films under argon (Ar) environment have been examined before and after irradiating with the Ar2+ ions of energy 500 keV. The pristine film stabilized with Magneli phase (Ti4O7), the film retains its crystallinity but phase get transformed to anatase TiO2, irradiating with the lowest fluence, 1 × 1014 ions/cm2. After rising up to 5 × 1016 ions/cm2 ion fluence, film again stabilize with the Magneli phase (Ti4O7). In the previous report, we have demonstrated an unusual phase change from anatase TiO2 to brookite, where films are annealed in O2 atmosphere. In contrast to that here we have obtained TiO2 from Ti4O7 at lowest fluence but at highest fluence again Ti4O7 is obtained. The energy deposited by the ion beam passed to the lattice and collision cascades are formed which brings atomic displacement in the lattice, results the structural transformation. Surface topography is not affected much after the irradiation as observed from atomic force microscopy (AFM). Interesting, ferromagnetic behavior at room temperature stems in all the films as a consequence of the controlled introduction of anionic defects (oxygen vacancies).

Who Owns What? Psychological Ownership in Shared Augmented Reality

Psychological ownership defines how we behave in and interact with the social world and the objects around us. Shared Augmented Reality (shared AR) may challenge conventional understanding of psychological ownership because virtual objects created by one user in a social place are available for other participants to see, interact with, and edit. Moreover, confusion may arise when one user attaches a virtual object in a shared AR environment onto the physical object that is owned by a different user. The goal of this study is to investigate tensions around psychological ownership in shared AR. Drawing on prior work, we developed a conceptualization of psychological ownership in shared AR in terms of five underlying dimensions: possession, control, identity, responsibility, and territoriality. We studied several shared AR scenarios through a laboratory experiment that was intended to highlight normative tensions. We divided participants into pairs, whereby one participant in each pair created the virtual object (object-creator) and placed it over the other person's (space proprietor) physical object or space. We recorded participants’ perceptions of psychological ownership along the 5 dimensions through surveys and interviews. Our results reveal that the paired participants failed to form a mutual understanding of ownership over the virtual objects. In addition, the introduction of virtual objects called into question participants’ sense of psychological ownership over the physical articles to which the virtual objects were attached. Building on our results, we offer a set of design principles for shared AR environments, intended specifically to alleviate psychological ownership-related concerns. Herein, we also discuss the implications of our findings for research and practice in this field.

An AR based Digital Twin for Laser based manufacturing process monitoring

In the modern manufacturing era, monitoring systems evolve towards sophistication and complexity, introducing numerous challenges in the feasibility, the assembly, the efficiency, and the integration of process monitoring devices on the relative equipment. The current work introduces a novel digital AR based digital twin framework, enabling real-time information analysis and advanced data visualization of monitoring performance on process monitoring systems. The main goal of the current research is to provide a dynamic AR environment, capable of simulating the main system’s functionalities, minimizing the configuration time, cost, and inaccuracies. The case study introduced regards the configuration of optics for thermal emissions capturing from laser based processes, while the coexistence with other aspects of monitoring, such as in the case of Remote Laser Welding is considered. The usability of the tool is shown and visualization issues encountered are presented.

Synthesis and properties of NiSi2-LiNbO3 heterostructures fabricated by radio-frequency magnetron sputtering

Thin LiNbO3 films were synthesized by radio-frequency the magnetron sputtering method on nickel silicide (NiSi2) substrates in a pure Ar atmosphere and an Ar+O2 gas mixture. The as-grown LN-NiSi2 heterostructures fabricated in an Ar environment exhibited high-quality rectifying current-voltage (I-V) characteristics due to the presence of an oxide charge, making the band diagram nonsymmetrical. The charge transport is determined by space-charge-limited currents via electronic traps distributed in the bandgap of LiNbO3 with a concentration of Nt=2.0•1015 cm-3. By contrast, I-V characteristics of LN-NiSi2 heterostructures fabricated in an Ar+O2 gas mixture were symmetrical due to decreasing in the oxide charge amount. The trap concentration rises to Nt=3.0•1018 cm-3 when the oxygen content in a reactive chamber increases to 60%. As-grown LiNbO3 films manifested good isolating properties with the resistivity of 8•109 Ohm•cm. The pulsed photon treatment increases the resistivity of LN films by six orders of magnitude, turning their I-V characteristics into Ohmic-like which makes this post-growth technique not suitable for the studied heterostructures.

Atomic layer deposition of ZnO thin film on ZrO2 dental implant surface for enhanced antibacterial and bioactive performance

ZnO thin film was deposited on ZrO2 plates by Atomic Layer Deposition, and the ZrO2/ZnO plates were annealed at 200 °C, 225 °C, 250 °C and 275 °C in Ar environment for 2 h. The characterization results showed that a higher annealing temperature resulted in increased grain size, surface roughness and hydrophilicity. The antibacterial and bioactive properties of ZrO2/ZnO thin-film composite were studied with Streptococcus Sanguinis (SS), Bifidobacterium (BB), and Porphyromonas Gingivalis (PG) bacteria. The ZnO thin film annealed at 250 °C exhibited the best biocompatibility and antibacterial performance.

Effect of Mo-doping in SnO2 thin film photoanodes for water oxidation

New semiconducting metal oxides of various compositions are of great interest for efficient solar water oxidation. In this report, Mo-doped SnO2 (Mo:SnO2) thin films deposited by reactive magnetron co-sputtering in the Ar and O2 gas environment are studied. The Sn to Mo ratio in the films can be controlled by changing the O2 partial pressure and the deposition power of the Sn and Mo targets. Increasing the Mo concentration in the film leads to the increase in the oxygen vacancy density, which limits the maximum achievable photocurrent density. The thin films exhibit a direct band gap of 2.7 eV, the maximum achievable photocurrent density of 0.6 mA cm−2 at 0 VRHE and the onset potential of 0.14 VRHE. The incident photon to current transfer (IPCE) efficiency of 22% is shown at a 450 nm wavelength. The initial performance of the Mo:SnO2 thin films is evaluated for solar water oxidation.

Effect of CNT on microstructural properties of Zn2SiO4/CNT composite via dry powder processing

This work focused on the influence of carbon nanotubes (CNT) to the microstructural properties of Zn2SiO4/CNT (ZSO/CNT) composite. CNT was synthesized via alcohol catalytic chemical vapor deposition (ACCVD) using cobalt oxide as catalyst and ethanol as carbon source. Zinc silicate (ZSO) glass was prepared from quenching the melted commercial waste glass bottle with zinc oxide powder. ZSO/CNT-x composites with various CNT concentration (0, 1, 2 and 3 wt%) was prepared through introducing CNT into ZSO glass via dry processing technique followed by sintering process in Argon gas (Ar) environment and atmospheric (atm) environment, respectively. FESEM, XRD and EDS were employed to determine the surface morphology, phase composition and elemental distribution of sintered sample. Crystallite trigonal willemite (Zn2SiO4) phase was observed from argon sintered sample and the crystallite size of willemite phase in ZSO/CNT-3/Ar showed the most reduced lattice strain of 22.85% compared to ZSO/CNT-0/Ar. In contrast, semi-crystalline phase exhibited in atmospheric sintered sample resulted in high lattice strain. It is concluded that dry powder processing and inert gas thermal treatment can be an effective technique in fabricating strain-reduced ceramics/CNT composite without alternating the domain phase. Least internal strain in crystal lattice have potential on enhancing the luminescence properties of phosphor material and lattice thermal conductivity of thermoelectric material.

SnS nanocrystalline thin films for n-CdS/p-SnS solar cell devices

Tin sulfide (SnS) thin films were galvanostatically electrodeposited on glass/Indium-Tin Oxide (ITO)/Cadmium Sulfide (CdS) substrates from a non-aqueous solution. The effect of different DL-tartaric acid concentrations and various annealing environments (vacuum, air and argon) on the electrical and physical properties, secondary phase formation and performance of the solar cells were investigated in this study. From X-ray diffraction (XRD) and Raman spectra, nanocrystalline SnS thin films with orthorhombic structure were produced with some secondary phases of SnS2 and Sn2S3 which decreased by annealing in air and Ar atmospheres. Cyclic voltammetry studies showed that the films have good electrochemical properties and photoluminescence analysis indicates that the samples have a direct band gab energy about 1.55 eV. Chemical composition and morphological structure of the nanoparticles were identified using energy dispersive X-ray analysis and scanning electron microscopy, respectively. The current–voltage (I–V) characteristics (under dark) and capacitance–voltage (C–V) relations for the fabricated devices (glass/ITO/n-CdS/p-SnS/Mo), for the SnS thin film annealed under Ar environment, exhibited a rectifying behavior with a saturation current and carrier concentration of ~ 10−6 A and 1016 cm−3, respectively. The illuminated cell have an efficiency of 4.35%, which was investigated with an illumination intensity of 100 mW/cm2 and the output parameters; short circuit current density (Jsc), open circuit voltage (Voc) and fill factor (FF) are 13.6 mA/cm2, 1000 mV and 0.32, respectively.

VISUALIZATION OF POINT CLOUD MODELS IN MOBILE AUGMENTED REALITY USING CONTINUOUS LEVEL OF DETAIL METHOD

Abstract. Point clouds have become one of the most popular sources of data in geospatial fields due to their availability and flexibility. However, because of the large amount of data and the limited resources of mobile devices, the use of point clouds in mobile Augmented Reality applications is still quite limited. Many current mobile AR applications of point clouds lack fluent interactions with users. In our paper, a cLoD (continuous level-of-detail) method is introduced to filter the number of points to be rendered considerably, together with an adaptive point size rendering strategy, thus improve the rendering performance and remove visual artifacts of mobile AR point cloud applications. Our method uses a cLoD model that has an ideal distribution over LoDs, with which can remove unnecessary points without sudden changes in density as present in the commonly used discrete level-of-detail approaches. Besides, camera position, orientation and distance from the camera to point cloud model is taken into consideration as well. With our method, good interactive visualization of point clouds can be realized in the mobile AR environment, with both nice visual quality and proper resource consumption.

Effect of reactive gas composition on properties of Si/LiNbO3 heterojunctions grown by radio-frequency magnetron sputtering

Amorphous lithium niobate (LiNbO 3 ) films were deposited onto silicon substrates by the radio-frequency magnetron sputtering method in a pure Ar environment and an Ar + O 2 gas mixture with various oxygen contents. The oxide charge existing in as-grown films has two components: the positive +Q ox distributed in the bulk of a film and the negative −Q ox located at the film/substrate interface with a maximum magnitude corresponding to an Ar (80%) + O 2 (20%) gas mixture. The potential barrier height, φ , at the LiNbO 3 /Si interface correlates with Q ox . The lowest φ value is attributed to the LiNbO 3 /Si heterostructures fabricated under an Ar/O 2 = 60/40 gas ratio. The electron traps, affecting the charge transport are distributed exponentially in the bandgap of as-grown amorphous LN films with the “smoothest” distribution, corresponding to the films deposited in an Ar (60%) + O 2 (40%) gas mixture. Thermal annealing (TA) leads to the crystallization of as-grown films, decreasing the −Q ox value greatly in heterostructures fabricated in an Ar + O 2 environment, and declining the φ value. The φ value is insensitive to the crystallization of LN films deposited in a pure Ar environment. The recrystallization process occurring under TA turns the trap distribution into uniform one. The dielectric constant of polycrystalline LiNbO 3 films, fabricated in both (Ar (80%) + O 2 (20%) and Ar (60%) + O 2 (40%)) gas mixtures and annealed at 550 °C, is higher than that of the films deposited in a pure Ar atmosphere.

Effects of the joining process on the microstructure and properties of liquid-phase-sintered SiC-SiC joints formed with Ti foil

The joining of liquid-phase sintered SiC (LPS-SiC) ceramics was conducted using spark plasma sintering (SPS), through solid state diffusion bonding, with Ti-metal foil as a joining interlayer. Samples were joined at 1400 °C, under applied pressures of either 10 or 30 MPa, and with different atmospheres (argon, Ar, vs. vacuum). It was demonstrated that the shear strength of the joints increased with an increase in the applied joining pressure. The joining atmosphere also affected on both the microstructure and shear strength of the SiC joints. The composition and microstructure of the interlayer were examined to understand the mechanism. As a result, a SiC-SiC joining with a good mechanical performance could be achieved under an Ar environment, which in turn could provide a cost-effective approach and greatly widen the applications of SiC ceramic components with complex shape.

Influence of pressures in a hyperbaric environment on the penetration during pulsed laser welding of 304 stainless steels and its influence mechanism

Developing laser welding (LW) technology in a hyperbaric environment is significant for manufacturing and maintaining nuclear power facilities, offshore engineering structures, etc. However, the penetration is significantly reduced during LW in a hyperbaric environment, which has not been solved yet. Previous research has shown that compared with the penetration of LW in a hyperbaric argon (Ar) environment, the penetration of 304 stainless steels attained through LW in a hyperbaric environment can be remarkably increased when using helium (He) as the shielding gas on same conditions. Hence, the plasma and molten pool behaviors in the LW process of 304 stainless steels in a hyperbaric He atmosphere were systematically explored. Furthermore, the effect of the growth of ambient pressure on the process of pulsed laser spot welding of 304 stainless steels was analyzed. It was found that when ambient pressure gradually rose from 0.1 to 1.8 MPa, the height and the intensity of characteristic plasmas above the molten pool gradually increased. In the initial stage of welding, the expansion velocity of plasmas under 1.8 MPa was about 1/4 of that under 0.6 MPa; the growth rate of the molten pool depth under 1.8 MPa was about 1/13 of that under normal pressure (0.1 MPa). The increase in ambient pressure led to the great decrease in weld penetration. Under experimental conditions in this paper, the weld penetration at the ambient pressure of 1.8 MPa was only 25% of that at normal pressure (0.1 MPa).

تصمیم نمط بیئة الواقع المعزز لتنمیة مهارات تکنولوجیا القدرة والتخیل العلمى لدى طلاب التعلیم الثانوى الصناعى

هدف هذا البحث إلى تصميم نمط بيئة الواقع المعزز لتنمية مهارات تکنولوجيا القدرة والتخيل العلمى لدى طلاب التعليم الثانوى الصناعى، وإعداد القوائم التالية: 1- إعداد قائمة بمهارات تکنولوجيا اليکترونيات القدرة لدى طلاب التعليم الثانوى الصناعى. 2- إعداد قائمة بمهارات التخيل العلمى لدى طلاب التعليم الثانوى الصناعى. 3- إعداد قائمة بمعاييرالتصميم التعليمى لنمط تصميم بيئة الواقع المعزز. 4- تقديم تصميم لبيئة واقع معزز قائمة على نمطى(الأکواد- الصور) لتنمية مهارات تکنولوجيا إليکترونيات القدرة لدى طلاب التعليم الثانوى الصناعى. نتائج البحث: توصلت الباحثة من خلال اتباع مجموعة من الخطوات العلمية إلى الإجابة عن أسئلة البحث وهى إعداد وتقديم ما يلى: 1- قائمة بمهارات تکنولوجيا اليکترونيات القدرة وعددها 7 مهارات. 2- قائمة بمهارات التخيل العلمى وعددها 7 مهارات. 3- قائمة بمعاييرالتصميم التعليمى لنمط تصميم بيئة الواقع المعزز وعددها 8 معايير. 4- تصميم لبيئة واقع معزز قائمة على نمطى(الأکواد- الصور) لتنمية مهارات تکنولوجيا إليکترونيات القدرة لدى طلاب التعليم الثانوى الصناعى. The aim of this research is to know the design of the augmented reality environment pattern to develop the ability and scientific imagination technology skills of industrial secondary education students, and to prepare the following lists: 1- Preparing a list of the ability of electronic technology skills for industrial secondary education students. 2- Preparing a list of scientific imagination skills of industrial secondary education students. 3- Preparing a list of educational design criteria for the AR environment design pattern. 4- Presenting a design for an augmented reality environment based on two models (codes - images) to develop the ability of electronic technology skills for students of industrial secondary education. research results: The researcher, by following a set of scientific steps, reached an answer to the research questions, namely, preparing and presenting the following: 1- A list of the 7 skills of electronic power technology. 2- A list of the 7 skills of scientific visualization. 3- A list of 8 standards for the instructional design of the augmented reality environment design. 4- Designing an augmented reality environment based on two patterns (codes - images) to develop the ability of electronic technology skills for students of industrial secondary education.

Revealing unique energy level alignment at graphene/MoS2 2-dimensional layered junction using in situ ambient pressure x-ray photoelectron spectroscopy

The chemical/electronic structures of a 2-dimensional (2D) molybdenum disulfide (MoS2) monolayer were characterized using ambient pressure x-ray photoelectron spectroscopy (APXPS) under various gas environments. APXPS results captured the binding energy shifts for the MoS2 chemical states that represent the electronic-structure of the 2D MoS2 monolayer in a real gas environment. The effect of the presence of a 2D graphene (Gr) layer on the properties of the 2D MoS2 layer was simultaneously characterized. When coating a Gr layer on the MoS2 layer, electron injection from MoS2 to Gr occurs due to the Schottky barrier at the interface. As a result, the Gr layer and MoS2 layer attain relatively more n-type and p-type characteristics, respectively, compared to when they exist separately. The hole-injection barrier, formed between the MoS2 layer and the SiO2 substrate, is lower by about 0.3 eV in the Gr/MoS2/SiO2 structure compared to that in the MoS2/SiO2 structure. This gap in the energy level alignments is stable so that there is no change in Ar, N2, O2, and CO2 environments. Taken together, our results not only present an appropriate methodology for fabricating 2D material-based device components, but also suggest the need for consideration of the charge transfer at the MoS2/Gr junction when applied to a practical device.

The domain structure and local switching of LiNbO3 thin films deposited on Si(001) by radio-frequency magnetron sputtering

Ferroelectric domain structure and local switching were studied in LiNbO3 thin films deposited by radio-frequency magnetron sputtering technique on Si (001) substrates in Ar and Ar(60%)+O2(40%) environments. The noticeable difference in surface morphology and ferroelectric domain structure of the investigated films was found. The films sintered in pure Ar environment demonstrated pronounced <0001> texture; nevertheless, neither piezoresponse nor ferroelectric domains were obtained. Films sintered in Ar(60%)+O2(40%) environment possessed the switchable ferroelectric domain structure but disordered grain orientation. The films sintered in Ar after thermal annealing in air preserve <0001> texture and possess self-poled switchable domain structure.

Deposition-environment-dependent structural and magnetic property modification of [111]-oriented epitaxial CoFe2O4 films

We examined the magnetic, structural, and chemical properties of CoFe2O4 films deposited on Al2O3 substrates using RF-magnetron sputtering under Ar and Ar + O2 environments. Perpendicular magnetic anisotropy with large magnetization was observed in the case of the film deposited under the Ar + O2 environment. However, no significant anisotropy appeared in the film deposited under the Ar environment. Interestingly, depth-dependent X-ray photoelectron spectra showed nearly identical stoichiometric ratios of Co/Fe and oxygen vacancies regardless of the deposition environment. Structurally, high-quality crystallinity with in-plane compressive strain, and lower surface and interfacial roughness were induced in the film deposited under the Ar + O2 environment. Cross-sectional transmission electron microscopy and X-ray reflectivity measurements showed that oxygen not only suppressed the deposition rate but also increased the electron density of the film, resulting in better crystallinity. Hence, the presence of oxygen during deposition should be considered as one of the essential parameters for improving the structural and magnetic properties of ferrite films.

Growth of Ge clathrate on sapphire and optical properties

Type II Ge clathrate (NaxGe136) films containing a small amount of Na were successfully synthesized on a sapphire substrate by thermal annealing of precursor NaGe composite films. A new technique for Na removal from NaxGe136 was developed by applying the electric field in an Ar environment at 275 °C. Rietveld refinement analysis of NaxGe136 films showed an almost guest free nature (Na contents x ∼ 0) using this new technique. In addition, absorbance spectra obtained from NaxGe136 films showed a decrease in the absorbance intensity in the lower photon energy (<0.5 eV) with annealing. It suggests the decrease in free carrier absorption by the removal of Na atoms in NaxGe136.

Oxide charge evolution under crystallization of amorphous Li–Nb–O films

Li–Nb–O amorphous films were deposited onto Si substrates by the radio-frequency magnetron sputtering method in an Ar environment and an Ar(60%)+O 2 (40%) gas mixture. A positive effective fixed oxide charge Q eff having negative, -Q eff , and positive, +Q eff , components, exists in the as-grown heterostructures. -Q eff is located near the substrate/film interface, whereas + Q eff is determined by a deficit of Li and O (vacancies) in the bulk of Li–Nb–O films. As-grown films crystallized under thermal annealing (TA) at temperatures up to 600 °C and revealed the formation of polycrystalline LiNbO 3 . TA at about 520 °C resulted in the formation of the second phase LiNb 3 O 8 , increasing + Q eff , and compensating -Q eff entirely. The dielectric constants of the as-grown films exhibit two peaks at the annealing temperatures of 450 °C and 550 °C, which are attributed to the total crystallization and recrystallization of the LN films under TA, respectively.

PbMoO4 Synthesis from Ancient Lead and Its Single Crystal Growth for Neutrinoless Double Beta Decay Search

A powder synthesis of PbMoO4 (PMO) from ancient lead (Pb) and deeply purified commercial MoO3 powders was performed using a wet chemistry technique to achieve the low radioactivity scintillator for neutrinoless double beta decay search in 100Mo. The synthesized powders were used to grow single crystals of PbMoO4 by the Czochralski technique in an Ar environment. The luminescence and scintillation properties were measured with excitations using UV, X- and γ-rays in the temperature range of 10–300 K. Annealing of the grown PMO crystal in an air atmosphere significantly enhanced the scintillation light yield compared to that measured before annealing. The scintillation light yield of grown PMO crystal at 10 K was found to be 127% to that of a reference PMO crystal under 662 keV γ-rays excitation from a 137Cs source. The background measurement of the grown crystal performed at 50 K shows a lower internal activity from 210Pb compared to that of reference PMO (grown from modern Pb) crystal. These preliminary performances show that the PMO crystal grown from ancient Pb and deeply purified MoO3 powders has a great potential to be used as a cryogenic scintillator for the neutrinoless double beta decay search in 100Mo.