Gas Reaction Method Research Articles

Sublimated Se‐Induced Formation of Dual‐Conductive Surface Layers for High‐Performance Ni‐Rich Layered Cathodes

AbstractNi‐rich layered oxide cathode materials for Li‐ion batteries have received widespread attention owing to their high specific capacity and comparatively low cost. However, owing to Li‐containing surface residues, side reactions with the electrolyte and structural rearrangement after long‐term cycling leads to severe degradation of the cathode performance. Here, Se coating serves as a novel and simple sublimation‐inducing gas reaction method to modify the Ni‐rich layered material, resulting in capacity retention and rate performance improvement. The sublimed gaseous Se reacts with residual Li compounds to form a Li2SeO4 coating on the surface of the secondary particles, which simultaneously promotes the transmission of Li ions and reduces electrode‐electrolyte side reactions. Moreover, gaseous Se penetrates between the primary particles within the secondary particles to promote electron transmission. This dual‐conductive surface layer facilitates superior capacity and voltage retentions. Significantly, the proposed method is scalable and applicable to all Ni‐rich cathode materials.

Prediction of Thermal Expansion Coefficients using the Second Phase Fraction and Void of Al-AlN Composites Manufactured by Gas Reaction Method

Prediction of Thermal Expansion Coefficients using the Second Phase Fraction and Void of Al-AlN Composites Manufactured by Gas Reaction Method

Efficient and Stable Inverted Planar Perovskite Solar Cells Employing CuI as Hole‐Transporting Layer Prepared by Solid–Gas Transformation

AbstractThe inorganic p‐type semiconductor CuI possesses several unique characteristics such as high transparency, low‐production cost, high hole mobility, and good chemical stability and is a promising hole‐transporting material candidate that can be explored in solar‐cell devices. Herein, we adopt a simple solid–gas reaction method to fabricate a uniform CuI film by exposing a thermally evaporated copper film to iodine vapor and apply it as a hole‐transporting layer (HTL) in inverted planar perovskite solar cells (PSCs). The optimized devices display a promising power conversion (PCE) efficiency of 14.7 %, with an open‐circuit voltage of 1.04 V, a short‐circuit current density of 20.9 mW cm−2, and a fill factor of 0.68. This is one of the highest PCE values reported so far for CuI‐based HTL in PSCs. Moreover, the devices studied also exhibit good long‐term stability at ambient atmosphere, arising from the hydrophobicity of CuI HTL. The results highlight that CuI fabricated using the simple and low‐temperature processing method presented here holds great promise as low‐cost alternative HTL material for the development of efficient and stable inverted planar PSCs in the future.

Theoretical study of hydrogen desorption on Mg50Ni50 using statistical physics treatment

In this work, Mg50Ni50 hydrogen storage alloy was synthesized by mechanical alloying technique, by using a planetary high energy ball mill (Retsch PM 200). The morphological and microstructural characterization of the powders was performed via scanning electron microscopy and X-ray diffraction. The dehydriding characterization of the composite was performed via a solid gas reaction method at different temperature 313 K, 333 K and 353 K. A new model has been developed, describing pressure-composition isotherms basing on statistical physics treatment. The monolayer model with two types of sites is found to fit very well with experimental data obtained on Mg50Ni50. The parameters involved in the model were determined directly from the experimental data by numerical simulation. The behaviors of these parameters are discussed in relationship with absorption and desorption process. Finally, the different thermodynamical potential functions are derived by statistical physics calculations from the adopted model.

Optical properties of Cu2S nano-hollow cactus arrays with different morphologies

In this study, a series of Cu2S nano-hollow cactus arrays (CNHC) with varying morphologies is prepared by a two-step process including electrodeposition and the solid–gas reaction method. The structure of the arrays is characterized by scanning electron microscopy, X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, and Raman spectroscopy; while, their light absorption performance is investigated by diffuse reflectance and photoluminescence spectroscopy. The “thorns” of the CNHC are single-crystal Cu2S semiconductors, and the band gap of the CNHC can be adjusted by changing their morphology, where the light absorption ability of the array is enhanced from 82% to 93% as the thorn diameter decreases from 1500 to 163nm. All of the different CNHC morphologies exhibit little sensitivity to the incident angle of the light. For example, the light absorption of the CNHC with a thorn diameter of 430nm only decreases by 5% as the incident angle increases from 0° to 45°. This shows the potential of the CNHC for use in solar energy applications, where its insensitivity to the angle of the incident light will reduce the necessity of adjusting the angle of solar cell panels using CNHC in the photovoltaics.

Role of Cl on Diffusion of Cu in In2S3 Layers Prepared by Ion Layer Gas Reaction Method

Ion layer gas reaction (ILGAR) method allows for deposition of Cl-containing and Cl-free In2S3 layers from InCl3 and In(OCCH3CHOCCH3)3 precursor salts, respectively. A comparative study was performed to investigate the role of Cl on the diffusion of Cu from CuSCN source layer into ILGAR deposited In2S3 layers. The Cl concentration was varied between 7 and 14 at.% by varying deposition parameters. The activation energies and exponential pre-factors for Cu diffusion in Cl-containing samples were between 0.70 to 0.78 eV and between 6.0 × 10−6 and 3.2 × 10−5 cm2/s. The activation energy in Cl-free ILGAR In2S3 layers was about three times less compared to the Cl-containing In2S3, and the pre-exponential constant six orders of magnitude lower. These values were comparable to those obtained from thermally evaporated In2S3 layers. The residual Cl-occupies S sites in the In2S3 structure leading to non-stoichiometry and hence different diffusion mechanism for Cu compared to stoichiometric Cl-free layers.

Deposition of very thin uniform indium sulfide layers over metallic nano-rods by the Spray-Ion Layer Gas Reaction method

Very thin and uniform layers of indium sulfide were deposited on nickel nano-rods using the sequential and cyclical Spray-ILGAR® (Ion Layer Gas Reaction) technique. Substrates were fabricated by electrodeposition of Ni within the pores of polycarbonate membranes and subsequent chemical dissolution of the template. With respect to the depositions on flat substrates, experimental conditions were modified and optimized for the present geometry. Our results show that nano-rods up to a length of 10μm were covered uniformly along their full length and with an almost constant film growth rate, thus allowing a good control of the coating thickness; the effect of the deposition temperature was also investigated. However, for high numbers of process steps, i.e. thickness, the films became uneven and crusty, especially at higher temperature, mainly owing to the simultaneous side reaction of the metallic Ni forming nickel sulfide at the surface of the rods. However, such a problem occurs only in the case of reactive nano-rod materials, such as less noble metals. It could be strongly reduced by doubling the spray step duration and thereby sealing the metallic surface before the process step of the sulfurization. Thus, quite smooth, about 100nm thick coatings could be obtained.

Effect of amorphous Mg50Ni50 on hydriding and dehydriding behavior of Mg2Ni alloy

Composite Mg{sub 2}Ni (25 wt.%) amorphous Mg{sub 50}Ni{sub 50} was prepared by mechanical milling starting with nanocrystalline Mg{sub 2}Ni and amorphous Mg{sub 50}Ni{sub 50} powders, by using a SPEX 8000 D mill. The morphological and microstructural characterization of the powders was performed via scanning electron microscopy and X-ray diffraction. The hydriding characterization of the composite was performed via a solid gas reaction method in a Sievert's-type apparatus at 363 K under an initial hydrogen pressure of 2 MPa. The dehydriding behavior was studied by differential thermogravimetry. On the basis of the results, it is possible to conclude that amorphous Mg{sub 50}Ni{sub 50} improved the hydriding and dehydriding kinetics of Mg{sub 2}Ni alloy upon cycling. A tentative rationalization of experimental observations is proposed. - Research Highlights: {yields} First study of the hydriding behavior of composite Mg{sub 2}Ni (25 wt.%) amorphous Mg{sub 50}Ni{sub 50}. {yields} Microstructural characterization of composite material using XRD and SEM was obtained. {yields} An improved effect of Mg{sub 50}Ni{sub 50} on the Mg{sub 2}Ni hydriding behavior was verified. {yields} The apparent activation energy for the hydrogen desorption of composite was obtained.

The spray-ILGAR ® (ion layer gas reaction) method for the deposition of thin semiconductor layers: Process and applications for thin film solar cells

The spray Ion Layer Gas Reaction (ILGAR) process starts with ultrasonic nebulisation of the precursor solution, e.g. InCl 3/ethanol for our successful buffer material In 2S 3. In an aerosol assisted chemical vapour deposition (AACVD) type reaction an In(O,OH,Cl) film is deposited on a heated substrate and is subsequently converted to In 2S 3 by H 2S gas. The cycle of these steps is repeated until the required layer thickness is obtained. The robust and reproducible process allows a wide control of composition and morphology. Results of this “spray-ILGAR” method with respect to process, material properties and its application depositing the buffer layer in chalcopyrite solar cells are reviewed. New aspects such as the investigation of the complex chemical mechanism by mass spectrometry, the process acceleration by the addition of H 2S gas to the aerosol, the controlled deposition of ZnS nano-dot films and finally the latest achievements in process up-scaling are also included. Solar cells based on industrial Cu(In,Ga)(S,Se) 2 absorbers (Avancis GmbH) with a Spray-ILGAR In 2S 3 buffer reached 14.7% efficiency (certified) and 15.3% with a ZnS/In 2S 3 bi-layer buffer comparable to reference cells using standard CdS buffer layers deposited by chemical bath deposition (CBD). The quasi-dry, vacuum-free ILGAR method for In 2S 3 buffer layers is well suited for industrial in-line production and is capable of not only replacing the standard buffer material (the toxic CdS) but also the often slow CBD process. A tape coater for 10 cm wide steel tape was constructed. It was shown that In 2S 3 layers could be produced with an indium yield better than 30% and a linear production speed of 1m/min. A roll-to-roll pilot production line for electrochemically deposited Cu(In,Ga)Se 2 with ILGAR buffer is running in industry (CIS-Solartechnik, Hamburg). A 30x30 cm 2 prototype of an ILGAR in-line coater developed by Singulus and Helmholtz Zentrum Berlin is currently being optimised. First 30×30 cm 2 encapsulated modules achieved efficiencies up to 13.0% (CdS buffered reference 13.3%).

Spatially resolved characterization of chemical species and crystal structures in CuInS2 and CuGax Sey thin films using Raman microscopy

AbstractThis study demonstrates the potential of Raman microscopy in the analysis of thin film cross‐sections. Raman maps of the photovoltaic material CuInS2 (CIS), which was prepared by the spray ion layer gas reaction method, revealed the spatial distribution of two different CIS modifications – chalcopyrite‐type and CuAu I‐type CIS – as well as contaminants and segregates with a lateral resolution of approx. 400 nm. Additionally, the chemical heterogeneity of a CuGaSe2/CuGa3Se5 bi‐layer stack was clearly resolved. Raman microscopy provides a convenient way to simultaneously probe the chemical and structural properties of a sample. Based on Raman spectra, chemical species and even different crystal structures of inorganic compounds can be identified. Knowledge of the distribution of different phases and contaminants in thin films is crucial for further improvements of the coating process. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Fabrication of nanostructured CuInS 2 thin films by ion layer gas reaction method

CuInS 2 thin films were prepared by a two-stage ion layer gas reaction (ILGAR) process in which the Cu and In precursors were deposited on glass substrate by using a simple and low-cost dip coating technique and annealed in H 2S atmosphere at different temperatures. The influence of the annealing temperature (250–450 °C) on the particle size, crystal structure and optical properties of the CuInS 2 thin films was studied. Transmission electron microscopy revealed that the particle radii varied in the range 6–21 nm with annealing. XRD and SAED patterns indicated polycrystalline nature of the nanoparticles. The optical band gap ( E g) varied from 1.48 to 1.56 eV with variation of particle size. The variation of Urbach tail with temperature indicated higher density of the defects for the films annealed at lower temperature. From the Raman study, it was observed that the FWHM of the A 1 mode at ∼292 cm −1 corresponding to the chalcopyrite phase of CuInS 2 decreased with increasing annealing temperature.

Synthesis of single-crystalline CeB6 nanowires

Abstract A self-catalyst metal–gas reaction method for the synthesis of cerium hexaboride (CeB6) nanostructures was presented. Large-scale CeB6 nanowires have successfully been fabricated with self-catalyst method using Ce powders and boron trichloride (BCl3) gas mixed with hydrogen and argon. X-ray diffraction, scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM) were used to characterize the structures, morphologies and compositions of the samples. Our results show that CeB6 nanowires have a diameter around 20–100 nm and the length extending to several micrometers. Transmission electron microscopy (TEM) reveals that CeB6 nanowires are single crystals with cubic structure. Our investigation forms part of a series of studies for finding comparatively inexpensive method to prepare RB6 nanomaterials.

Characterization of CuInS 2 thin films prepared by ion layer gas reaction method

Ion layer gas reaction (ILGAR) method for CuInS 2 films was developed by using ethanol as solvent. The influences of [Cu] / [In] ratio in ethanol solution on structural, chemical, topographical, optical and electrical properties of CuInS 2 thin films were investigated. X-ray diffraction and X-ray photoelectron spectroscopy results showed that all CuInS 2 thin films derived from different [Cu] / [In] ratios were sphalerite with preferred orientation (112). Scanning electron microscopy revealed that the microstructure and the growth rate of the films depended on the relative amounts of copper in the solution. When [Cu] / [In] ratio was 1.50 growth rate of the film was about 30 nm/cycle and the film was uniform, compact and good in adhesion to the substrates. The absorption coefficients of CuInS 2 films estimated from transmittance spectra were more than 10 4 cm − 1 , and the films behaved with p-type conductivity. The band gap E g changed from 1.30 to 1.40 eV and the dark resistivity decreased from 3.1 to 0.04 Ω cm with increase of [Cu] / [In] ratio.

무성-연면 복합방전형 오존발생기의 오존생성 및 NO 가스 제거특성

본 논문에서는 대기오염물질인 Nitrogen Oxides(NO) 가스를 제거하기 위하여 3개의 전극이 장착된 하나의 방전 공간에 무성방전과 연면방전을 동시에 발생가능한 복합방전형 오존발생기를 설계·제작하였다. 전압인가 방식에 따라 3가지 형태의 오존발생기로 구성가능한 복합방전형 오존발생기에 유입하는 산소원료가스의 유량, 방전전력 및 오존발생기의 종류에 따른 방전 및 오존생성특성을 연구·검토한 결과, 8334[ppm] 및 3249[mg/h]의 오존을 얻을 수 있었다. 또한 NO(1200[ppm])/N₂ 가스의 입력방식에 따른 NO 가스 제거특성을 방전전력 및 오존발생기의 종류에 따라 연구·검토한 결과, 최대 100[%]의 제거율을 얻을 수 있었다.

ILGAR CuInS 2 films from various preparation conditions

CuInS 2 thin films were prepared by ion layer gas reaction (ILGAR) method using C 2H 5OH as solvent, CuCl and InCl 3 as reagents and H 2S gas as sulfuration source. The effects of cationic precursor concentration and numbers of dipping cycles on characteristics of CuInS 2 film were investigated. The results shows that the chalcopyrite CuInS 2 with near stoichiometry can be deposited as [In 3+] ≤ 0.05 M and [Cu +] ≤ 0.078M ([Cu +]/[In 3+] = 1.55), while Cu x S segregation phase appears with further increasing cationic concentration. Its deposition rate is close to constant as cationic concentration is fixed, and nonlinearly increases with increasing the cationic concentration. CuInS 2 thin film derived from lower cationic concentration is uniform, compact and good in adhesion to the substrates. The absorption coefficient of CuInS 2 thin films is larger than 10 4 cm −1, and the optical band gap E g is 1.30∼1.40 eV and has a slight fall with increase of the cationic concentration. The dark resistivity decreases from ∼50 to ∼10 Ω cm and the carrier concentration ranges over 10 16 cm −3.

Cd 2 + ∕ N H 3 -treatment of Cu(In,Ga)(S,Se)2: Impact on the properties of ZnO layers deposited by the ion layer gas reaction method

Cu ( In , Ga ) ( S , Se ) 2 - (“CIGSSe”) based solar cells with a ZnO layer deposited by the ion layer gas reaction (ILGAR) method yield superior efficiencies (15.0%) than the references with a chemical bath-deposited CdS buffer (14.1%). However, this high performance is only reached if the absorber is pretreated in a Cd2+- and aqueous ammonia-containing bath prior to the ILGAR-ZnO deposition. The photovoltaic as well as the dark device parameters are strongly influenced by this treatment. Scanning and transmission electron microscopy (TEM) as well as x-ray diffraction measurements reveal a different morphology and structure of ILGAR-ZnO layers on top of Cd2+∕NH3-treated and on as-deposited absorbers, indicating a considerably modified absorber surface. By energy dispersive x-ray analysis in the TEM, Cd could only be identified at the ILGAR-ZnO∕Cd2+∕NH3-treated-CIGSSe interface of the respective cross sections, if the absorber was treated in a bath with an atypically high Cd2+-concentration. In this case a Cd-containing thin layer between ZnO and CIGSSe was observed in TEM images.

Optical analysis of nanocrystalline thin layers deposited by the ion layer gas reaction method

Nanocrystalline ZnS thin layers are prepared by ion layer gas reaction, a low cost deposition method for compound semiconductor thin films. They are investigated by optical spectroscopy, x-ray fluorescence and energy dispersive x-ray analysis. It is seen that the absorption edges are shifting towards lower photon energies with increasing layer thickness. Also, the amount of unconverted precursor salt is decreased. A simulation procedure for fitting the determined absorption edges of these layers is introduced. This leads to particle size distribution functions showing an increasing broadening with increasing layer thickness. Moreover, the distribution maximum is moving to larger crystallite radii with larger film thickness. Both results indicate a growth in crystallite size during the layer deposition. Additionally, the increase in strength of the phonon-photon-coupling confirms the conclusions of transmission electron micrographs. Later investigations show that the noncrystalline precursor matrix which surrounds the ZnS crystallites is vanishing with increasing layer thickness. Therefore, the nanocrystallites are more frequently in contact with each other. This again favors the propagation of phonons.

Hydriding/dehydriding properties of magnesium–ZrCr2 composites

Composites of Mg and the intermetallic compound (IMC) ZrCr2 have been prepared by mechanical alloying. The crystallographic structure, composition and morphology of the composites were analysed by means of X-ray diffraction (XRD) and energy dispersive X-ray analysis (EDX). XRD patterns show that no alloy formation takes place during milling. EDX data show that milling time is a key parameter to control the morphology of the composites. Short milling times of 10 min give composites with the IMC attached to the Mg particle surface, while it is irregularly distributed in the Mg bulk for longer milling times of 70 min. Hydriding/dehydriding properties of the composites were studied by the solid–gas reaction method. Composites with a distribution of the IMC in the Mg bulk are easily activated and show faster hydriding/dehydriding kinetics than untreated Mg, which indicates that ZrCr2 acts as a catalytic compound for the Mg–hydrogen reaction.

SYNTHESIS AND STRUCTURE OF Ga2O3 NANOSHEETS

Monoclinic gallium oxide nanosheets were synthesized on a large scale through a simple gas reaction method. They were characterized by means of X-ray powder diffraction (XRD), field emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDS), high-resolution transmission electron microscopy (HRTEM), and Raman spectroscopy. FE-SEM images showed that the product was mainly composed of nanosheets. XRD, EDS and Raman spectra indicated the nanosheets were a monoclinic gallium oxide structure. An HRTEM lattice image revealed that the nanosheets are nearly uniform in structure and single crystalline.

Fabrication of zinc oxide nanorods

ZnO nanorods with diameters of 10–200 nm were fabricated through a simple gas reaction method. They were characterized by means of powder X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray (EDX) spectroscopy and transmission electron microscopy (TEM). FE-SEM and TEM images showed that the product was composed of nanorods with lengths from several to tens microns. XRD and EDX indicated that the nanorods were hexagonal ZnO.