Influences of Ga concentration on performances of CuInGaSe2 cells fabricated by sputtering-based method with ceramic quaternary target

Copper Indium Gallium Selenide (Cu(In,Ga)Se₂, CIGSe) absorbers with different Ga contents were prepared by sputtering CIGSe ceramic targets and post-annealing. CIGSe solar cell devices were fabricated with other functional layers. The device performances and absorber properties were investigated. Increasing Ga content led to an increase in V_OC and a decrease in J_SC. Ga was supposed to diffuse towards back contact during the annealing process. The best performance was obtained as the ratio of Ga/(In + Ga) reaches 0.32 with the efficiency of 13.8% and a V_OC of 537 mV.     

The role of sulphur in the sulfurization of CZTS layer prepared by DC magnetron sputtering from a single quaternary ceramic target

The influence of sulphur vapour pressure, controlled by its mass, on the grain growth and optoelectronic properties of Cu₂ZnSnS₄ (CZTS) films prepared by a two-step procedure based on sputtering was studied. It was found that both the crystallinity and grain size of the films were promoted with the increase of the sulphur vapour pressure, indicating that the crystal growth was controlled by the sulphur vapour pressure. In addition, the crystal growth process of CZTS was investigated by analysing the microstructure and elemental composition of the sulfurized films with different masses of sulphur. It was also found that the content of Sn in the sulfurized films decreased after high-temperature annealing. However, the second phase SnS₂ was observed on the sample surface, which led to the increase of the optical band gap of the film. Moreover, we proposed the regulatory mechanism of sulphur vapour pressure in the grain growth of CZTS film. Finally, a highly crystalline p-type kieserite Cu₂ZnSnS₄ film with carrier concentration of 8.16?×?10¹⁷ cm^?3, mobility of 1.24?cm²/V?s and optical bandgap of 1.54?eV was obtained. This CZTS layers are expected to fabricate high efficiency thin film solar cells.     

Influence of the selenization time on the properties of (Na0.1Cu0.9)2ZnSn(S,Se)4 thin films and their photovoltaic solar cells

(Na_0.1Cu_0.9)₂ZnSn(S,Se)₄ thin films with a single kesterite phase were synthesized using a sol-gel spin-coating method accompanied by rapid post-annealing. In this study, we investigated the effect of selenization time on the crystal quality and photoelectric performance of the (Na_0.1Cu_0.9)₂ZnSn(S,Se)₄ films. It was found that the crystallinity and morphology of the films was enhanced, and some of bigger Se substituted for the S site in (Na_0.1Cu_0.9)₂ZnSn(S,Se)₄ with increasing the selenization time. The bandgap of the film can be regulated from 1.04 eV to 0.99 eV by varying the selenization time. In addition, all films showed p-type conductive characteristics, and films with optimal electrical performance could be obtained by optimizing the selenization time. Finally, the (Na_0.1Cu_0.9)₂ZnSn(S,Se)₄ thin film with the best crystal quality and optical-electrical characteristics was obtained at an optimized selenization time of 15 min. A high power conversion efficiency (PCE) of 3.92% was obtained for the (Na_0.1Cu_0.9)₂ZnSn(S,Se)₄ device, which is 42% higher compared to that of the undoped Cu₂ZnSn(S,Se)₄ (CZTSSe) device.     

Effects of ethyl acetate additive on Cu2ZnSnS4 solar cells fabricated with a facile dimethylformamide-based solution coating process

The solution based on dimethylformamide (DMF) has shown promising application prospects in the fabrication of high-efficiency Cu₂ZnSnS₄ solar cells. However, due to the high boiling temperature of the solvent, it is difficult to completely volatilize DMF during the evaporation process after spin coating, leading to remains of C and O atoms at grain boundaries, which severely restricts the photoelectric performance of solar cells. In this study, ethyl acetate (EA) with green character was used as an additive to optimize the film formation process of DMF-based CZTS precursor. The experimental results showed that using a small amount of EA additives could effectively improve morphology, crystallinity, composition distribution and electrical properties of the CZTS absorber. In addition, the CZTS and CdS heterojunctions exhibited a cliff-like energy band structure, and the optimized conduction band offset increased the activation energy required for the carrier recombination path, consequently reducing the carrier recombination. Compared with the pure DMF precursor solution, the photoelectric conversion efficiency of CZTS solar cells with an EA addition ratio of 10% was improved by 42%, and the open circuit voltage of the device reached 601 mV.     

Influence of shear stress state on dynamic fracture of a glass ceramic Macor

The effect of shear stress on the dynamic failure of ceramic materials is not sufficiently investigated in the published literature. With the use of a bespoke split Hopkinson pressure bar, this paper presents an effort to investigate the dynamic shear compressive response of Macor, a model ceramic material with zero porosity and light weight characteristics. A cone specimen and cylindrical specimens with varying inclined angles are used to introduce the shear stress to the Macor ceramic. The dynamic failure initiation and crack propagation are monitored by the high speed photography and Digital Image Correlation techniques. It is found that the equivalent stress of Macor at the initiation of failure decreases nonlinearly with the increase of shear stress. The high speed images show that the crack originates from the minimum cross-section of the cone specimen and the obtuse angle corner of the inclined cylindrical specimens. The cracks propagate parallel to the inclined plane instead of the axial loading direction. The fractographic analysis shows the compacted zone in the shear fracture surfaces of the cone specimen and the inclined cylindrical specimens. This indicates a significant role of shear loading in the dynamic failure process of Macor.     

联箱式陶瓷滤管排的脉冲喷吹系统的研究

对共用一个喷嘴和引射器的联箱式陶瓷滤管排的喷吹性能进行了实验研究并得出结论,认为扩压管式引射器动态性能优于文氏管引射器和直管引射器,且喷嘴至引射器有一最佳距离     

Controlled synthesis of TiO2 nanorod arrays immobilized on ceramic membranes with enhanced photocatalytic performance

In this work, TiO₂ nanorod arrays (NRAs) were synthesized directly on flat sheet Al₂O₃ ceramic membrane (CM) substrates by a two-step hydrothermal method. The effects of the addition of anions and cations and the preparation parameters in the second step on the morphology and size of TiO₂ were investigated in detail, and the photocatalytic activities of the as-synthesized TiO₂-loaded ceramic membranes were investigated by the degradation of methylene blue (MB) under UV light. The results highlighted that the growth of TiO₂ on the CM strongly depended on the synthesis conditions. The anions of Cl^- and Br^- were favorable for the further growth of TiO₂ nanorods, while the anions of SO₄^2- and PO₄^3- with larger ionic radius and higher charge number could retard the growth of TiO₂ nanorods. The SO₄^2- and PO₄^3- could accelerate the formation of nanospheres or nanosheets, respectively. The cation like Na⁺, K⁺, Mg²⁺ and Ca²⁺ had no obvious impact on the formation of TiO₂ NRAs. TiO₂ nanorods exhibited the highest photocatalytic activity, as about 2.2 and 1.9 times larger than those of TiO₂ nanosheets and TiO₂ nanospheres, respectively. More importantly, the as-synthesized TiO₂ NRAs-loaded ceramic membrane could be easily reused and exhibited better photocatalytic stability. These findings would aid the development of TiO₂ photocatalytic materials with high performance.     

Sorption of NaOH and NaOC6H5 on quaternary ammonium resin in a fixed‐bed adsorber

The sorption behaviours of NaOH and NaOC₆H₆₅ on quaternary ammonium resin with functional groups of ‐NMe⁺₄CI^? (hydrophilicity) and ‐NBu⁺₄Cl^? (lipophilicity) in an aqueous fixed‐bed adsorber were investigated. The types of resins and salts, salt concentration, and operating temperature were evaluated to achieve the optimum sorption conditions. The probability distribution function of the breakthrough curve was employed to describe the sorption system. The parameters of probability distribution function, sorption rate, exchange capability, height of mass‐transfer zone and degree of saturation were also obtained. The effective exchange capacities for hydrophilic resins were found to be smaller than those for lipophilic resins. The sorption capability of NaOC₆H₅ in the resin was larger than that of NaOH.     

Influence of silicon carbide as a mineralizer on mechanical and thermal properties of silica-based ceramic cores

Ceramic cores have been designed with compounds based on fused silica due to its excellent thermal stability and chemical inertness against molten metals. To endure the high temperatures present during investment casting, mineralizers have been widely used to enhance the flexural strength and shrinkage of ceramic cores. In this study, we demonstrated a silica-based ceramic core with silicon carbide as a mineralizer for improving the mechanical and thermal properties. The SiC in the silica-based ceramic cores can enhance the mechanical properties (i.e., flexural strength and linear shrinkage) by playing a role as a seed for the crystallization of fused silica to cristobalite. The SiC also improves the thermal conductivity due to its higher value compared with fused silica. The results suggest that using the optimal amount of silicon carbide in silica-based ceramic cores can provide excellent mechanical properties of flexural strength and linear shrinkage and improved thermal conductivity.     

热处理对电沉积制备CuInGaSe2薄膜的影响

CuInGaSe2薄膜太阳能电池因具有稳定、高效、低成本和环保等特点而受到国内外科学家的重视．采用Mo／钠钙玻璃衬底为研究电极，饱和甘汞电极(SCE)为参比电极，大面积的铂网电极为辅助电极的三电极体系，在钼／钠钙玻璃衬底上利用电沉积技术制备出太阳能电池用的CuInGaSe2薄膜．分析了不同热处理温度对电沉积制备的CuInGaSe2薄膜的影响，结果表明：当热处理温度为450℃时，所制备的CuInGaSe2薄膜的化学组成接近理想的化学计量比，薄膜具有黄铜矿结构，颗粒均匀和致密性较好．     

Ultra-high temperature oxidation resistance of a novel (Mo,Hf, W,Ti)Si2 ceramic coating with Nb interlayer on Ta substrate

In order to solve the challenge of recyclability of tantalum substrates in high temperature oxidation environments, a novel MoSi₂-WSi₂-HfSi₂-TiSi₂ composite ceramic coating containing an Nb interlayer was prepared on the surface of tantalum substrate by a three-step method. The mix ceramic silicide coating exhibited superior performance and effective protection for 10.2 h at 1800 °C, possibly due to the formation of an outer SiO₂-HfO₂-HfSiO₄ composite oxide film with low oxygen permeability, moderate viscosity and thermal expansion coefficient, as well as good self-healing ability. Furthermore, the coating successfully passed 537 thermal cycles from room temperature to 1800 °C. The presence of Nb interlayer significantly mitigated the thermal mismatch between the ceramic coating and the tantalum substrate, and the bidirectional diffusion of Nb element during the high temperature oxidation and thermal shock process further reduced the tendency of the coating to crack.     

Development of ceramic coatings on titanium alloy substrate by laser cladding with pre-placed natural derived-slurry: Influence of hydroxyapatite ratio and beam power

The attraction towards Ti and its alloys reside in their superior mechanical and tribological features, as compared to CaPs, which are renowned for their compositional and structural features similar to those of natural bones. However, Ti-based materials suffer from limited biocompatibility and inertness when implanted for extended periods. As such, surface modification with ceramic coatings is required in order to achieve proper biomedical features and enhance their overall behavior in the human body. Hence, this study outlined for the first time the prospect of coating several Ti6Al4V substrates (disks) with bovine-bone derived hydroxyapatite (HA) by laser cladding technique with pre-placed slurry. During laser processing the input materials merge depending on the heating rate/temperature and clad materials. The proposed sample preparation set-up, followed for the first time in this study, involved the concomitant modulation of two parameters: the natural HA ratio (100 wt%, and 50 wt% HA + 50 wt% Ti blends) and laser beam power (500–1000 W range). The laser beam was applied after the ceramic slurries (prepared HA/HA-based blends mixed with polyvinyl alcohol) were placed inside the priorly machined channels on the metallic Ti disks. Partially overlapped cladding tracks (～30% overlapping ratio) resulted and the investigations were further performed in cross-section view. The structural analyses confirmed the formation of calcium titanate as main phase for all samples and the arrest of HA only for those prepared with 100% HA ratio at low to medium laser powers. In addition, the morpho-compositional evaluation revealed the formation of a fully ceramic coating only for the latter sample sets. Further, the surface wettability (contact angle and surface free energy) and Vickers micro-hardness results led to the selection of the optimal technological parameters for the development of ceramic cladded layers with prospect compatibility with regenerative medicine applications.     

Green synthesis of Ln2Zr2O7 (Ln = Nd,Pr) ceramic nanostructures using extract of green tea via a facile route and their efficient application on propane-selective catalytic reduction of NOx process

In this paper, we present the fabrication of Ln₂Zr₂O₇ (Ln = Nd, Pr) ceramic nanostructures with green tea extract (GrTeEx) as novel and efficacious fuel through easy and repeatable route as well as their application in propane-selective catalytic reduction of NO_x process (propane-SCR-NO_x), for the first time. As-fabricated samples with green tea extract have been examined via diverse kind of techniques. Our outcomes represented the successful production of the pure nanostructured Ln₂Zr₂O₇ (Ln = Nd, Pr) in presence of green tea extract as novel and efficacious fuel. Moreover, the nanostructured samples can be utilized as a potential novel kind of catalysts with desirable efficiency for propane-SCR- NO_x. It was found that Pr₂Zr₂O₇ denoted better performance than Nd₂Zr₂O₇ for NO_x abatement so that the conversion of NO_x in to N₂ for Pr₂Zr₂O₇ was 67% and for Nd₂Zr₂O₇ was 56%. Also the concentration of CO production for Pr₂Zr₂O₇ which is inevitable and undesirable product in SCR-NOx process with hydrocarbons such as propane was lower than Nd₂Zr₂O₇.     

Optimization of TiO2 paste concentration employed as electron transport layers in fully ambient air processed perovskite solar cells with a low-cost architecture

The optimization of thickness and surface roughness of the TiO₂ layer as an efficient electron transporting layer (ETL) plays a significant role on the performance improvement of perovskite solar cells (PSCs). In the present investigation, TiO₂ pastes synthesized with various concentrations under hydrothermal conditions were utilized to deposit the TiO₂ films of tunable porosities as the ETLs of PSCs. Also, the PSCs were fabricated with a structure of FTO/block-TiO₂ (b-TiO₂)/m-TiO₂/CH₃NH₃PbI₃ (MAPbI₃)/CuInS₂ (CIS)/carbon as a low-cost architecture. Moreover, the effect of the TiO₂ paste concentration was studied on the performances of PSCs under fully ambient conditions. The optimal TiO₂ layer was constructed with 20 wt% TiO₂ paste concentration, which resulted in the formation of a hole‐free, smooth, and compact ETL layer. The champion perovskite solar cell fabricated with the 20 wt% TiO₂ paste concentration showed the highest power conversion efficiency (PCE) of 13.09% (J_SC = 20.80 mA cm^?2, V_OC = 0.98 V and FF = 0.64) but the champion PSC device made with the 10 wt% TiO₂ paste exhibited the lowest PCE = 8.05% (J_SC = 19.83 mA cm^?2, V_OC = 0.91 V and FF = 0.45). These results illustrated that the optimal 20 wt% TiO₂ paste caused ～163% enhancement in the PCE of the device. Consequently, it could be suggested for application in fabrication of cost-effective and large scale PSCs.     

Effect of the Y2O3 additive concentration on the properties of a silicon nitride ceramic substrate

Silicon nitride (Si₃N₄) ceramics offer excellent thermal, mechanical and dielectric properties, which make Si₃N₄ a good candidate material for an application as electronic packaging material. For an application as a heat dissipation substrate, most studies focused on achieving a high thermal conductivity through long-time heat preservation and different kinds of heat treatments. Very few studies also considered the mechanical and dielectric properties. In addition, there have not been systematic researches about influence of additives concentration and type on the combination properties of Si₃N₄. Therefore, in this study, Si₃N₄ ceramic samples were prepared via hot pressing at 1800 °C with a relatively short heat preservation step (2 h), with different amounts of Y₂O₃ added as sintering additive. The effect of the initial concentration of the rare earth oxide on the chemical composition, microstructure, thermal conductivity, as well as the mechanical and dielectric properties of the Si₃N₄ ceramic samples was systematically studied.     

Ultrafiltration behaviors of pectin-containing solution extracted from citrus peel on a ZrO<Subscript>2</Subscript> ceramic membrane pilot unit

Ultrafiltration experiments on a solution of pectin, hesperidin, and other mixtures extracted from citrus peels have been performed on a 500 l/min pilot scale crossflow ceramic membrane unit. A 30,000 molecular weight cut-off (MWCO) zirconia (ZrO₂) ceramic membrane with a total effective flow area of 0.5 m² was used in the process. The permeate flux for pure water and hesperidin showed linear relationship with transmembrane pressure (ΔP), but the flux for pectin solutions showed a curvilinear relationship with ΔP and represented a rapid increase with increasing ΔP before leveling-off. Similar behavior was observed by adding different amounts of hesperidin to these pectin solutions, but with much lower permeate flows. The formation of gel layers on the membrane surface is mainly responsible for the lower permeate fluxes. In addition, the permeate flux decrease faster at higher ΔP, since higher ΔP brought bigger flux at lower pectin concentration. Compared with the more than 90% retention rate of macromolecular pectin, pigment and other component have less than 20% retention rate. So, the decolorization, the separation and purification of pectin preparations could be achieved simultaneously through ultrafiltration with a ceramic membrane.     

Influence of beta-to-alpha quartz transition on residual stresses of a feldspar glass matrix composite: A relationship with catastrophic fracture due to thermal shock

A wide range of porcelain-based materials is composed of quartz crystalline particles dispersed in a homogeneous glassy phase. During the cooling stage these composites are subjected to stresses related to the transition from β to α quartz at 573 °C. This work studies, numerically and experimentally, the influence of the cooling rate, the quantity, and the size of the quartz crystalline particles on the stresses suffered by the material throughout the cooling process. This procedure allows calculating the instantaneous profile of stresses through the cross-section specimen during the whole cooling stage. For this, a dense glass matrix from sodium feldspar was prepared. The results reveal that the evolution of the stress profile is strongly affected by the cooling rate. The evolution of the tension state in the sample during the cooling can help to understand the catastrophic fracture suffered during the β to α quartz transition related to thermal shock.     

Improved conversion efficiency of Ag2S quantum dot-sensitized solar cells based on TiO2 nanotubes with a ZnO recombination barrier layer

We improve the conversion efficiency of Ag2S quantum dot (QD)-sensitized TiO2 nanotube-array electrodes by chemically depositing ZnO recombination barrier layer on plain TiO2 nanotube-array electrodes. The optical properties, structural properties, compositional analysis, and photoelectrochemistry properties of prepared electrodes have been investigated. It is found that for the prepared electrodes, with increasing the cycles of Ag2S deposition, the photocurrent density and the conversion efficiency increase. In addition, as compared to the Ag2S QD-sensitized TiO2 nanotube-array electrode without the ZnO layers, the conversion efficiency of the electrode with the ZnO layers increases significantly due to the formation of efficient recombination layer between the TiO2 nanotube array and electrolyte.     

Asymmetric TiO2 hybrid photocatalytic ceramic membrane with porosity gradient: Effect of structure directing agent on the resulting membranes architecture and performances

Asymmetric TiO₂ hybrid photocatalytic ceramic membranes with porosity gradient have been fabricated via acid-catalyzed sol–gel method. Different structure directing agents (SDAs) i.e. Pluronic P-123, Triton X-100, Tween 20 and Tween 80 were incorporated in the preparation of TiO₂ sol to obtain a porous multilayered TiO₂ coated on the alumina ceramic support. Six different SDA-modified membrane specimens were fabricated. Four of which were coated with the TiO₂ sols prepared using only one type of SDA. The remaining two specimens were fabricated via multilayer coating of different TiO₂ sols prepared using different types of SDAs. Physico-chemical and morphological properties of different TiO₂ layers were thoroughly investigated. The membrane M1 which had the most porous TiO₂ sub-layers showed a high pure water permeability of 155 L m⁻² h⁻¹ bar⁻¹. The membrane showed a relatively high Rhodamine B (RhB) removal of 2997 mg m⁻² over 8 h treatment duration in the batch photoreactor, second only to the Pluronic-based TiO₂ membrane (specific RhB removal of 3050 mg m⁻²). All membrane specimens exhibited good performances while operated in the flow-through photocatalytic membrane reactor. Over 91% of RhB removal capability was retained after 4 treatment cycles. All membranes also showed self-cleaning property by retaining >90% of initial flux after 4 treatment cycles. The flexibility of optimizing membrane performances by fine-tuning the porosity gradient configuration of the photocatalytic layer has also been demonstrated.