Non-vacuum Method Research Articles

Influence of different alloy elements on the color of copper alloy

In this paper, Zinc, Aluminium, Nickel, Tin, and Iron are chosen as alloy elements to investigate the influence of different alloy elements on the color of copper alloy. The elements in each experimental group were designed by the orthogonal experiment method. The alloy was prepared by the non-vacuum smelting method. The color of the alloy was determined by spectrophotometer and CIE1976L *a*b* color system. The influence of several common alloy elements on the color of the copper alloy was studied. The results show that the content of Zn had a significant effect on the red-green value of “a”, and with the content of Zn increasing from 10wt% to 16wt%, the value “a” decreased by 2.3. The content of Ni had a significant effect on the value of the blue-yellow value of “b”, and with the content of Ni increasing from 0.5wt% to 2.0wt%, the value “b” decreased by 3.5.

Synthesis of Quasi-two-dimensional Carbon Nanostructures in Atmospheric Plasma of the Arc Discharge Using WC-Co Hard Alloy Waste as a Catalyst

The results of experimental studies on carbon nanomaterials production in the plasma of an arc discharge initiated in an open air were presented. The possibility of using waste carbide tools as a catalyst for obtaining quasi-two-dimensional carbon nanostructures by the proposed non-vacuum electric arc method was revealed. It was concluded that the process of synthesis of carbon nanostructures and electric arc processing of waste based on tungsten and cobalt are compatible.

Heteroepitaxial Growth of an Ultrathin β-Ga2O3 Film on a Sapphire Substrate Using Mist CVD with Fluid Flow Modeling.

β-Gallium oxide (Ga2O3) has received intensive attention in the scientific community as a significant high-power switching semiconductor material because of its remarkable intrinsic physical characteristics and growth stability. This work reports the heteroepitaxial growth of the β-Ga2O3 ultrathin film on a sapphire substrate via mist chemical vapor deposition (CVD). This study used a simple solution-processed and nonvacuum mist CVD method to grow a heteroepitaxial β-Ga2O3 thin film at 700 °C using a Ga precursor and carrier gases such as argon and oxygen. Various characterization techniques were used to determine the properties of the thin film. Additionally, a computational study was performed to study the temperature distribution and different mist velocity profiles of the finite element mist CVD model. This simulation study is essential for investigating low to high mist velocities over the substrate and applying low velocity to carry out experimental work. XRD and AFM results show that the β-Ga2O3 thin film is grown on a sapphire substrate of polycrystalline nature with a smooth surface. HR-TEM measurement and UV-visible transmission spectrometry demonstrated heteroepitaxial β-Ga2O3 in an ultrathin film with a band gap of 4.8 eV.

Triboelectric Pressure Sensors Using Laser-Directed Synthesis of Strain-Induced Crumpled MoS2

Two-dimensional (2D) transition metal dichalcogenide (TMDC) nanomaterials are currently regarded as next generation electronic materials for future flexible, transparent, and wearable electronics. Due to the lack of compatible synthesis and study, however, the characteristic influences of 2D TMDC nanomaterials have been little investigated in the field of triboelectric nanogenerator (TENG) devices that are currently one of the main technologies for mechanical energy harvesting. In this report, we demonstrate a fast, non-vacuum, wafer-scale, and patternable synthesis method for 2D MoS2 using pulsed laser-directed thermolysis. The laser-based synthesis technique that we have developed can apply internal stress to MoS2 crystal by adjusting its morphological structure, so that a surface-crumpled MoS2 TENG device generates ~40% more power than a flat MoS2 one. Compared to other MoS2-based TENG devices, it shows high-performance energy harvesting (up to ~25 V and ~1.2 μA) without assistance from other materials, even when the counterpart triboelectric surface has a slightly different triboelectric series. This enhanced triboelectrification is attribute to work function change as well as enlarged surface roughness. Finally, the direct-synthesized MoS2 patterns are utilized to fabricate a self-powered flexible haptic sensor array. The technique we propose here is intended to stimulate further investigation of the triboelectric effects and applications of 2D TMDC nanomaterials.

Epitaxial growth of SiGe films by annealing Al–Ge alloyed pastes on Si substrate

A simple, low-cost, and non-vacuum epitaxial growth method to realize large-area semiconductors on crystalline silicon will become the game-changer for various applications. For example, we can expect the disruptive effect on the cost of large-scale III–V multi-junction solar cells if we could replace the high-cost germanium substrate with silicon–germanium (SiGe) on Si. For SiGe epitaxial growth, we attempted to develop a process using original Al–Ge pastes for screen printing and subsequent annealing. We compare two pastes including Al–Ge alloyed pastes with compositional uniformity in each particle and Al–Ge mixed pastes. We revealed that Al–Ge alloyed paste could form flatter SiGe film with much less residual pastes, supported by in-situ observations. The uniform and sufficient dissolution of the alloyed paste is responsible for these and led to higher average Ge-composition by annealing at 500 °C. The composition in SiGe was vertically graded up to ~ 90% at the topmost surface. These results show that printing and firing of Al–Ge alloyed paste on Si is the desirable, simple, and high-speed process for epitaxial growth of SiGe, which could be potentially used as the lattice-matched virtual substrate with III–V semiconductors.

Synthesis of Submicron Boron Carbide by the Non-Vacuum Method with Indirect Supply of the Thermal Energy of a DC Arc Discharge

The results of experimental studies demonstrating the possibility of obtaining boron-carbide powder by treating a mixture of carbon and amorphous boron containing a small amount of boron oxide with DC arc discharge plasma are presented. A feature of the applied nonvacuum electric-arc method for the synthesis of boron carbide is its implementation in an open air environment due to achievement of the effect of screening the reaction zone with gaseous oxide and carbon dioxide. In this case, the initial reagents are heated to the required temperatures by a DC arc discharge plasma burning in the immediate vicinity of the initial-material mixture in the cavity of the graphite crucible. The resulting material contains particles of boron carbide with a size in the submicron range, which are characterized by the “shell–core” type structure. The scheme of the discharge circuit of a laboratory reactor with horizontal arrangement of electrodes and an indirect supply of thermal energy to the initial reagents described in the paper makes it possible to significantly increase the content of the boron-carbide phase and reduce the content of the graphite impurity phase.

Synthesis and Characterization of Cu2ZnSnSe4 by Non-Vacuum Method for Photovoltaic Applications.

Wet ball milling was used for the synthesis of Cu2ZnSnSe4 (CZTSe) nanoparticles with a kesterite structure. The prepared nanoparticles were used for ink formulation. Surfactants and binders were added to improve the ink stability, prevent agglomeration, and enhance ink adhesion. The films deposited via spin coating were annealed at different temperatures using a rapid thermal processing system in the presence of selenium powder in an inert environment. Analytical techniques, such as X-ray diffraction, Raman spectroscopy, and Fourier-transform infrared spectroscopy, were used to confirm the formation of CZTSe nanoparticles with a single-phase, crystalline kesterite structure. Field-emission scanning electron microscopy and energy-dispersive X-ray spectroscopy were used to study the surface morphology and chemical composition of the thin films before and after annealing, with and without the sodium solution. The optoelectrical properties were investigated using ultraviolet-visible spectroscopy and Hall measurements. All the prepared CZTSe thin films exhibited a p-type nature with an optical bandgap in the range of 0.82–1.02 eV. The open-circuit voltage and fill factor of the CZTSe-based devices increased from 266 to 335 mV and from 37.79% to 44.19%, respectively, indicating a decrease in the number of recombination centers after Na incorporation.

Bonding mechanism and preparation process of titanium/iron composite thin sheet by non-vacuum rolling

As a new type of layered metal composite sheet, titanium/iron composite thin sheet has attracted much attention because it can meet the dual requirements of the environment and material properties. This paper reports a non-vacuum rolling method that is more suitable for preparing titanium/iron composite thin sheet in industrial production. Herein, the bonding mechanism of the layered metal composite sheet was elucidated by analyzing the forces on the sheets during the non-vacuum rolling process then it was applied to explain the influence mechanism of the rolling reduction rate on interfacial bonding properties. The titanium/iron composite thin sheet was prepared by non-vacuum rolling with a 65% rolling reduction rate, and the interfacial microstructure was studied to verify the accuracy of theoretical judgments. The results show that a shear deformation zone exists at the interface of the layered metal composite sheet in the rolling process. In this zone, the oxide film on the interface breaks, and the exposed fresh metal undergoes metallurgical bonding under the action of radial rolling force to form a composite interface. With the increase of rolling reduction rate, the range of the shear deformation zone expands, and the radial rolling force acting on the interface increase, which is the main reason for the improvement of the rolling reduction rate on the bonding effect. Shear deformation caused vast dislocations in the interface microstructure of composite sheet. The texture of the titanium layer has a certain width under the action of shear deformation. The texture of the iron layer is mainly α-fiber, caused by shear deformation. Moreover, broken oxide films and diffusion layers of titanium and iron elements were observed at the interface.

Ion-doped mesoporous bioactive glass: preparation, characterization, and applications using the spray pyrolysis method.

Biotechnology is used extensively in medical procedures, dentistry, statures, biosensors, bio electrodes, skin substitutes, and medicine delivery systems. Glass is biocompatible and can be used in permanent implantation applications without risk. The porosity of BG matrixes, combined with their huge specific surface area, greatly aids the formation of hydroxyl carbonate apatite. Zn-Doped bioglass can be made in the lab in a variety of ways, depending on how it will be used in medical treatment. The melt-quenching technique, spray pyrolysis method, sol–gel process for BG fabrication, spray drying method, and modified Stöber method are examples of such strategies. Spray pyrolysis is a comprehensive approach that is an undeniably versatile and effective material synthesis technology. It is a low-cost, non-vacuum method for producing materials in the form of powders and films that may be deposited on a variety of substrates, and is a straightforward method to adapt for large-area deposition and industrial production processes. For better utility in medical care, MBG fabricated in the laboratory should be characterized using various characterization methods such as SEM, TEM, BET, and XRD.

Preparation and characterization of zinc sulfide thin film by electrostatic spray deposition of nano-colloid

In this investigation, condensed and adhesive zinc sulfide (ZnS) layers were productively sprayed onto Fluorine doped Tin Oxide glass substrate at room temperatures using a facile, non-vacuum and economical electrostatic spray deposition (ESD) method. Used ZnS colloidal in the ESD process prepared by a one-pot thermolysis synthesis method. The effects of applied voltage, liquid flow rate, and distance of the nozzle to substrate on the morphology of ZnS thin films, were investigated. It revealed optimized conditions at the voltage of 24 kV, the flow rate of 1 μl/min, and nozzle to substrate distance of 8 cm. The ultraviolet-visible absorption spectroscopy revealed direct optical band gap of the deposited layer is around 3.44 eV. At a wavelength larger than 350 nm, the visible region (transparency area) of ZnS film was observed. Energy dispersion X-ray analysis and scanning electron microscope showed the ZnS film has a thickness of more than 300 nm with Zn1-xS (x ≈ 0.3–0.4) chemical composition.

Heteroepitaxial growth of β-Ga2O3 thin films on c-plane sapphire substrates with β-(AlxGa1-x)2O3 intermediate buffer layer by mist-CVD method

As a new-type of ultra-wide bandgap semiconductor, β-Ga2O3 has received widespread attention due to its great potential applications in high-power devices and deep ultraviolet photodetectors. However, the conventional material epitaxial growth methods (such as MBE, MOCVD and HVPE) are always based on the expensive vacuum equipment and time-consuming. In this work, a low-cost and non-vacuum mist-CVD method is used to grow β-Ga2O3 films heteroepitaxially on sapphire substrates. In order to improve the quality of β-Ga2O3 films, the β-(AlxGa1-x)2O3 is first grown on sapphire substrate and used as the intermediate buffer layer to epitaxially grow β-Ga2O3 film, which can decrease the lattice mismatch and improve the β-Ga2O3 quality. A series of characterization techniques are used to characterize the properties of samples. The results of XPS and UV-Vis tests show that the aluminum composition of β-(AlxGa1-x)2O3 films grown at 850 °C and 900 °C are 0.24 and 0.43, respectively, and the corresponding band gap is 5.36 eV and 5.55 eV respectively. After using β-(AlxGa1-x)2O3 as the intermediate buffer layer, the FWHM of β-Ga2O3 film is 1.131°, the RMS roughness is 3.04 nm, and it has an ideal band gap (4.91 eV), which demonstrates the obvious improvement compared to the sample without the intermediate buffer layer. This shows that β-(AlxGa1-x)2O3 as an intermediate buffer layer can significantly improve the quality of heteroepitaxially grown β-Ga2O3 films.

β-Ga2O3 epitaxial growth on Fe-GaN template by non-vacuum mist CVD and its application in Schottky barrier diodes

In this work, we report on demonstrating lateral β-Ga2O3 Schottky barrier diodes (SBDs) fabricated on Fe-GaN/sapphire (0001) substrates by using the non-vacuum, low-cost mist chemical vapor deposition (mist CVD) method for the first time. The x-ray diffraction scanning pattern identifies that β-Ga2O3 layers are grown with (−201) planes parallel to the (0001) plane of the GaN template, and the transmission electron microscopy shows that the β-Ga2O3 lattice is regularly and neatly arranged, indicating good crystal quality. β-Ga2O3 based SBDs with 4 and 20 µm anode–cathode lengths (LAC) exhibit the specific on-resistance (Ron,sp) of 1.58 and 39.8 Ω cm2 and breakdown voltage (Vbr) of 580 and 2400 V, respectively. The present results show the great potential of the non-vacuum and cost-effective mist CVD method as the epitaxial growth technique employed in β-Ga2O3 devices.

Synthesis of Cu 2 ZnSnSe 4 thin‐film solar cells from nanoparticles by a non‐vacuum mechanical ball milling and rapid thermal processing

A truly simple, reproducible, and environmentally friendly non-vacuum synthesis method for synthesising of carbon-free Cu2ZnSnSe4 (CZTSe) absorber layer has been presented. The stannite CZTSe nanoparticles with an average size of about 20 nm distributions were fabricated by an ambient mechanical milling procedure using Cu2Se, Zn, Sn, elemental selenium powders as raw materials and non-toxic ethanol as solvent. The compact CZTSe thin films were formed via an annealing treatment under Ar/Se atmosphere using rapid thermal processing. The optical properties of the obtained CZTSe thin films are the absorption coefficient (α) exceeding 104 cm−1 and E g of 0.91 eV. The electrical properties of the CZTSe thin films indicate p-type semiconductor behaviour. The photovoltaic properties of this solar cell are power conversion efficiency of 0.18%.

Laser-directed synthesis of strain-induced crumpled MoS2 structure for enhanced triboelectrification toward haptic sensors

Two-dimensional (2D) transition metal dichalcogenide (TMDC) nanomaterials are currently regarded as next-generation electronic materials for future flexible, transparent, and wearable electronics. Due to the lack of compatible synthesis and study, however, the characteristic influences of 2D TMDC nanomaterials have been little investigated in the field of triboelectric nanogenerator (TENG) devices that are currently one of the main technologies for mechanical energy harvesting. In this report, we demonstrate a fast, non-vacuum, wafer-scale, and patternable synthesis method for 2D MoS 2 using pulsed laser-directed thermolysis. The laser-based synthesis technique that we have developed can apply internal stress to MoS 2 crystal by adjusting its morphological structure, so that a surface-crumpled MoS 2 TENG device generates ~40% more power than a flat MoS 2 one. Compared to other MoS 2 -based TENG devices, it shows high-performance energy harvesting (up to ~25 V and ~1.2 μA) without assistance from other materials, even when the counterpart triboelectric surface has a slightly different triboelectric series. This enhanced triboelectrification is attribute to work function change as well as enlarged surface roughness. Finally, the direct-synthesized MoS 2 patterns are utilized to fabricate a self-powered flexible haptic sensor array. The technique we propose here is intended to stimulate further investigation of the triboelectric effects and applications of 2D TMDC nanomaterials. • Fast, non-vacuum, large-scale and patternable synthesis of 2D MoS 2 is developed by laser-directed thermolysis. • Surface morphology of MoS 2 is intentionally controlled by tuning laser synthesis mechanism. • Surface-crumpled MoS 2 shows high-performance triboelectric energy harvesting signals. • Improved triboelectrification is attributable to work function change, surface area enlargement, and secondary effects. • Self-powered flexible haptic sensor array is fabricated using directly patterned MoS 2 .

Синтез заполненных карбидом вольфрама многостенных углеродных нанотрубок в атмосферной плазме дугового разряда постоянного тока

Показана возможность синтеза многостенных углеродных нанотрубок в плазме дугового разряда постоянного тока, инициированного в открытой воздушной среде. Процесс синтеза реализован в полости графитового катода, в которой в качестве катализатора присутствует порошок вольфрама. Применяемый метод реализуется за счет генерации газообразного оксида углерода СО, экранирующего реакционную зону от кислорода воздуха, предотвращая окисление продуктов синтеза. Согласно данным рентгеновской дифрактометрии синтезированные порошковые материалы содержат более чем 85 об. % углеродных кристаллических фаз с графитоподобной структурой, а также содержат кубическую фазу вольфрама, две фазы карбида вольфрама WC и W2C. Согласно результатам просвечивающей электронной микроскопии продукт синтеза содержит углеродные нанотрубки, особенностью которых можно считать относительно большое количество слоев (до ~50 шт.) при диаметре до ~100 нм и длине до ~1.5 мкм. При этом внутри углеродных нанотрубок идентифицируются кристаллические объекты, соответствующие по структуре карбиду вольфрама WC.

Heteroepitaxial growth of α-Ga2O3 thin films on a-, c- and r-plane sapphire substrates by low-cost mist-CVD method

Abstract α-Ga2O3 has received wide attention as a wide bandgap semiconductor. Many reports have reported heterogeneous epitaxial growth of α-Ga2O3 thin films, which basically use c-plane (0006) sapphire as a substrate. However, research on the growth of α-Ga2O3 on substrates such as a-, r-plane sapphire is still lacking. This paper systematically analyzes the differences of α-Ga2O3 films grown on different sapphire substrates (a-, c- and r-plane) using the non-vacuum, highly scalable and low-cost mist-CVD method. The in-plane and out-of-plane orientations of all three samples were consistent with their substrates. A series of complementary measurements (XRD, XPS, AFM, TEM, and UV-Vis) were used to characterize the crystallinity, elemental composition, surface morphology, lattice structure, growth rate, and optical bandgap of the α-Ga2O3 grown on substrates of different plane. It is shown that compared to the samples on other two plane substrates, the c-plane α-Ga2O3 films has a smallest FWHM of 0.204°, an ideal band gap width of 5.29 eV, a small Root-Mean-Square (RMS) of 1.64 nm, a growth rate of 11.44 nm/min and a perfect lattice structure among all the three samples. Thus, the c-plane sapphire is more suitable for high-quality α-Ga2O3 growth compared to the other plane substrates.

Investigation of Optimum Conditions for Synthesis of Cu(In,Ga)Se2 Nanoparticles by Refluxing

Cu(In,Ga)Se2 (CIGSe) has been proven to be a better candidate as a light absorber layer in thin-film solar cells. However, most processes require high vacuum and high temperature during deposition, which results in significant loss of materials and is not applicable to a flexible substrate. Solution processes often involve low processing temperature and cheap precursor, can be used with flexible substrates, and offer the possibility of roll-to-roll manufacturing, potentially reducing manufacturing costs for the module. Here, we have experimentally investigated the optimum synthesis conditions for CIGSe nanoparticles fabricated by using a facile and a non-vacuum reflux method for low-temperature solution processes. By employing various reflux conditions by changing the temperature of heating mantle, single-phase CIGSe nanoparticles were synthesized at 200 °C. On the other hand, synthesized products with an impure multi-phase were formed at heating mantle temperatures lower than 200°C. XRD measurements confirmed that the Ga content of the CIGSe nanoparticles increased with increasing heating mantle temperature. In addition, the average diameter of the CIGSe nanoparticles increased with increasing reaction time from 5 min to 30 min at a fixed heating mantle temperature of a 200 °C. The optical band gap is calculated by using ultraviolet-visible (UV-Vis) absorption spectra, decreased from 1.69 eV to 1.29 eV with increasing reaction time due to the increased CIGSe nanoparticles size. From our results, we can conclude that the characteristics of the CIGSe nanoparticles can be effectively controlled by using simple growth conditions, thereby providing many advantages for the fabrication of absorber layers for use in CIGSe solar cells.

Optical and Electrical Properties of Graphite Thin Films Prepared by Different Methods

The paper reports on the structural, optical and electrical properties of graphite thin films prepared by two methods: the vacuum-free method "Pencil-on-semiconductor" and via the electron beam evaporation. Graphite thin films prepared by the non-vacuum method has annealed at a temperature of 920K.The transmission spectra of the investigated graphite films and the electrical properties of these thin films were measured at T = 300 K. The value of the height of barriers Eb at the grain boundaries and the temperature dependence of the electrical conductivity in the range ln(σ·T1/2) = f(103/T) were determined, It is established that the height of the barrier at the grain boundaries for the drawn graphite films is Eb = 0.03 eV, for annealed Eb = 0.01 eV and for the graphite films deposited by the electron beam evaporation Eb = 0.04 eV, ie for annealed film the barrier height is the smallest. It is shown that graphite films deposited by the electron beam evaporation reveals the highest transmittance (T550 ≈ 60%), and the transmission of drawn films is the lowest, annealing leads to its increase. The minimum values ​​of transmission at a wavelength λ = 250nm are due to the scattering of light at the defects that are formed at the grain boundaries. Annealed graphite films have been found to possess the best structural perfection because they have the lowest resistivity compared to non-annealed films and electron-beam films and have the lowest barrier height. Simultaneous increase of transmission in the whole spectral range, increase of specific electrical conductivity and decrease of potential barrier at grain boundaries of the annealed drawn graphite film clearly indicate ordering of drawn graphite flakes transferred onto anew substrate, which led to the reduction of light scattering and the improvement of charge transport due to the larger area of ​​overlap between graphite flakes.

SYNTHESIS OF TUNGSTEN CARBIDE-FILLED MULTIWALLED CARBON NANOTUBES BY DC ARC DISCHARGE PLASMA IN AMBIENT AIR

In this paper, the possibility of synthesizing multiwalled carbon nanotubes (CNTs) by DC arc discharge plasma in ambient air is shown. The synthesis takes place in a graphite cathode with a crucible shape using tungsten powder as a catalyst. In the non-vacuum synthesis method the CO atmosphere is generated in the reaction zone during the arcing, preventing the products of the synthesis from oxidation. According to the X-ray diffraction analysis (XRD), the synthesized product includes more than 85 vol % of carbon crystalline phases with a graphite-like structure, a cubic tungsten phase, and two phases of tungsten carbide WC and W2C. The transmission electron microscopy data shows that the product of the synthesis contains CNTs with a relatively large number of walls (up to ~50 pcs) (MWCNTs) with a diameter of up to ~100 nm and a length of up to ~1.5 μm. It was found that crystalline objects corresponding in structure to WC tungsten carbide are identified inside CNTs.

Phase transition behavior and defect analysis of CuSbS2 thin films for photovoltaic application prepared by hybrid inks

CuSbS2 (CAS) thin films were deposited via a non-vacuum hybrid ink method onto a Mo/soda lime glass (SLG) substrate. To fabricate the CAS films, Cu-Sb precursors were spin coated and then annealed with sulfur powder. During annealing, different amounts of sulfur powder were used to control the crystal orientation of the films. X-ray diffraction (XRD) patterns were employed to examine the crystal orientation by calculating the texture co-efficient and Lotgering factor. It was found that the S-flux amount during sulfurization was a critical parameter for controlling the crystal orientation and phase transition of the CAS structure. Originally, CAS has an orthorhombic structure; however, if the S-flux was higher than the optimum, a pseudo-phase transition from orthorhombic to cubic was observed. In addition, the electrical characteristics and defect properties were conducted for the solar cells prepared with various S-flux to understand the difference in the photovoltaic performances affected by the structural change. Admittance spectroscopy revealed that the defect levels were shallower in the CAS solar cell with an orthorhombic structure, which could have contributed to the better photovoltaic performance than that of the cubic structure. The CAS solar cell deposited with low S-flux exhibited dominant VS2+ defects; however, for excessive S-flux, CuSb2− became prominent.