Hf6Ta2O17/Ta2O5 composite ceramic: A new eutectic system

Eutectic oxides are considered as the most promising candidates applied in extreme environment for long periods, and the pace of exploring new eutectic systems has never stopped. In the present work, Hf₆Ta₂O₁₇/Ta₂O₅ eutectic system is firstly prepared by the joint process of solvothermal method and spark plasma sintering (SPS). Eutectic liquid phase produced during the process of SPS fills the closed-pores and promotes the sintering process. Orthorhombic-Hf₆Ta₂O₁₇ and tetragonal-Ta₂O₅ of both eutectic and hypereutectic systems show single crystal characteristics and are combined by coherent interface instead of grain boundaries. The clean and flat interface also shows the characteristics of single crystal diffraction without impurities and amorphous phase. Based on the analysis of microstructure, the sintering mechanism is proposed, and the potential application of Hf₆Ta₂O₁₇/Ta₂O₅ eutectic system is analyzed.     

Influence of Ta2O5 Interfacial Oxide Layer Thickness on Electronic Parameters of Al/Ta2O5/p-Si/Al Heterostructure

Silicon - We describe the impact of Ta2O5 interfacial oxide layer thickness (ranging from 100-350 nm) on electrical and structural properties of Al/Ta2O5/p-Si/Al Metal-Insulator-Semiconductor (MIS)...     

Evolution of Hot Corrosion Behavior of YSZ‐Ta2O5 Composites with Different YSZ/Ta2O5 Ratios

This study compares the hot corrosion performance of yttria‐stabilized zirconia (YSZ)‐Ta₂O₅ composite mixtures (TaYSZ) in the presence of molten mixture of Na₂SO₄ + V₂O₅ at 1100°C. The tested compositions vary from pure YSZ (0TaYSZ) to a Ta₂O₅‐dominating (70 wt% Ta₂O₅+ balance YSZ, 70TaYSZ) composite mixture with a gradual increase of Ta₂O₅. 50TaYSZ (50 wt% Ta₂O₅ + balance YSZ) sample forms a highly stable zirconium tantalum oxide. 50TaYSZ is more stable, both thermally and chemically in Na₂SO₄+V₂O₅ media at 1100°C, than other tested YSZ‐Ta₂O₅ (TaYSZ) composites, and shows a good hot corrosion resistance.     

Ti/IrO2-Ta2O5阳极电催化氧化法处理含酚废水

采用新型的钛基金属氧化物涂层电极(Ti/IrO2–Ta2O5)作为阳极,石墨作为阴极对含酚模拟废水进行电催化氧化降解实验。当电解条件为电压U=9.0V;电流I=2.5A;板间距d=3.0cm;电解质NaCl浓度20.0g·L-1,初始pH=7.0时,初始浓度为1000mg·L-1苯酚模拟废水电解90min后,处理效果较理想,其中电流和电解质浓度为主要影响因子。Ti/IrO2–Ta2O5阳极电催化氧化降解苯酚的过程符合一级反应动力学。     

Physico-chemical and antimicrobial properties of Ag/Ta2O5 nanocomposite coatings

Surface modification of surgical instruments is carried out in order to improve the antibacterial performance against the surgical site infections. Healthcare acquired infections (HAI) and Nosocomial infections are one of the leading causes of complications/deaths after surgery. There is an increasing trend of antibiotic resistance in bacteria such as, vancomycin-resistant Enterococcus (VRE), carbapenem-resistant Enterobacteriaceae (CRE), multi-drug-resistant Mycobacterium tuberculosis (MDR-TB), methicillin-resistant Staphylococcus aureus (MRSA), and Neisseria gonorrhoeae. Thus, surfaces that counteract the adherence and growth of bacteria are employed to avoid the infections. In present study, stainless steel 316 L (SS 316 L) was coated with Silver/Tantalum oxide (Ag/Ta₂O₅) nanocomposite using reactive magnetron sputtering. The as-sputtered Ag/Ta₂O₅ nanocomposite (a-Ag/Ta₂O₅) film was crystallized via thermal treatment at 400 °C. Due to the annealing, the AgNPs migrated to the surface through the columnar paths of the a-Ag/Ta₂O₅. Thus, the crystallized layer (c-Ag/Ta₂O₅) exhibited 302% improvement in adhesion strength and enhanced hydrophopibicity. The c-Ag/Ta₂O₅ also demonstrated excellent antibacterial performance against Staphylococcus aureus (NCTC 6571) (gram-positive bacteria) and Escherichia coli (ATCC 15597) (gram-negative bacteria) according to the inhibition zone measurements. These results suggest that c-Ag/Ta₂O₅ deposition on SS 316 L substrate has a high potential to serve as an adherent, antibacterial layer on the surgical tools, in order to resist surgical site infections.     

Study on properties of Hf6Ta2O17/Ta2O5 system: A potential candidate for environmental barrier coating (EBC)

Ta₂O₅ doped Hf₆Ta₂O₁₇ system (Hf₆Ta₂O₁₇/Ta₂O₅) is considered to have potential application prospect in the field of aero-engine. We herein focus on the thermo-physical, mechanical properties and CMAS corrosion resistance of Hf₆Ta₂O₁₇/Ta₂O₅ to systematically evaluate the possibility for the application of environmental barrier coating (EBC). By changing the content of Ta₂O₅, the gradient adjustment of thermal expansion coefficient can be realized while maintaining low thermal conductivity (1.5–2.2 W/(m·K)). The introduction of Ta₂O₅ significantly reduces the modulus and improves the fracture toughness. Single-phase Hf₆Ta₂O₁₇ shows excellent corrosion resistance against molten calcium-magnesium-alumina-silicate (CMAS). The crystallization of CaTa₂O₆ and HfSiO₄ is the important factor to prevent further corrosion. The introduction of Ta₂O₅ weakens the ability to prevent Si penetration and greatly increases the thickness of the corrosion layer. The results highlight the merit of Hf₆Ta₂O₁₇/Ta₂O₅ system as potential candidate for multi-layer gradient coating on the surface of ceramic matrix composites.     

Ti/IrO_2-Ta_2O_5电解-Fenton耦合法深度降解含酚废水

针对Fenton法处理废水效果不佳、试剂用量较大、投资成本较高的问题,采用形稳电极Ti/Ir O2-Ta2O5电解与Fenton耦合法处理含酚废水。考察了处理时间、p H值、电压、H2O2和Fe SO4·7H2O投加量对废水降解效果的影响,确定了Ti/Ir O2-Ta2O5电解与Fenton耦合法最佳工艺条件,对比研究了电Fenton法与Fenton法降解含酚废水效果。结果表明:随着处理时间、H2O2和Fe SO4·7H2O投加量的增加,苯酚和COD去除率呈现先增加后趋于平缓的趋势;随着p H值的升高呈现先增加后降低的趋势;在较低电压条件下,可获得良好的处理效果。在最佳工艺条件为p H值3.5、槽电压5.0 V、Fe SO4·7H2O投加量0.15 g/L、H2O2投加量0.3 m L/L、反应时间2 min时,处理初始质量浓度为100 mg/L的含酚废水,COD去除率为40.7%,苯酚去除率为94.2%,高于Fenton法苯酚去除率16.2%。电解与Fenton耦合法在较低电压条件下处理含酚废水,处理效果优于Fenton法,具有良好的应用前景。     

Highly transparent yttria ceramics with Nb2O5/Ta2O5 as novel sintering additives by pressureless vacuum sintering

Highly transparent yttria ceramics were fabricated by pressureless sintering with Nb₂O₅ or Ta₂O₅ as a novel sintering additive. The optical transmittance, microstructural evolution, and thermo-mechanical properties of the samples were investigated. The optimal doping concentrations of Nb₂O₅ and Ta₂O₅ are 0.3 and 0.2 at.%, respectively, which are much lower compared to those of previously reported counterparts. The transmittance of the sample with 0.3 at.% Nb₂O₅ reaches 81.6% at 1100 nm and 72.4% at 400 nm (2 mm in thickness), similar transmittance was obtained in the sample with 0.2 at.% Ta₂O₅. The microhardness (∼7 GPa), fracture toughness (∼0.85 MPa·m^1/2), and biaxial strength (∼200 MPa) of the present samples were confirmed to be comparable or even better compared to those of previously reported transparent yttria ceramics fabricated by pressureless sintering. Furthermore, the present samples, by virtue of the low doping concentrations, possessed relatively high thermal conductivity values (>10 W/m·K), which substantially guaranteed high thermal shock resistance.     

Propriétés photocatalytiques de Ta2O5/SiO2

The photocatalytic properties of deposited tantalum oxide (Ta₂O₅) on silica, in the reaction of photocatalytic oxidation of cyclohexane by oxygen, have been studied. The properties of this catalyst were compared with those of the previously studied system V₂O₅/SiO₂, and it was concluded that the mobilities of V⁺⁵ and Ta⁺⁵ ions on the surface of silica under radiation arc verymuch different. This study was completed by an analysis of the diffuse reflectance spectra and a thermogravimetric analysis of the used catalysts. The conclusion was that the site active in the photocatalytic reaction, is hydrated during the oxidation of cyclohexane.     

钛基纳米晶IrO_2-Ta_2O_5氧化物涂层阳极的研究

介绍运用扫描电镜、X射线衍射、循环伏安测试及加速寿命实验等方法研究了钛基纳米晶IrO2-Ta2O5氧化物涂层的制备和电化学性能。在使用热分解法获得纳米晶氧化物的过程中,钛基体机械前处理、涂层成分、烧结温度、烧结时间等制备因素均影响最终所得涂层氧化物纳米晶粒尺寸,从而使电极的电化学性能发生变化。     

Synthesis of Nb2O5 and Ta2O5 nanopowders by means of an endo-templating method

Finding efficient templates for the nanostructuring of materials is a key point. Here, the niobium (V) - and tantalum (V) oxide ceramics nanopowders have been synthesized by a hard-templating approach by using the tricalcium phosphate biomaterial (Ca₃(PO₄)₂.xH₂O) as template agent. The oxide ceramics were investigated by X-ray Diffraction (XRD), Fourier Transform Infrared (FTIR) spectroscopy, nitrogen physisorption and Scanning Electron Microscopy (SEM). It was observed that the surface properties (specific surface areas, pore volumes) of the Nb₂O₅ and Ta₂O₅ powders were strongly dependent of the amount of the Ca₃(PO₄)₂.xH₂O template previously used in the preparation of the [oxide ceramics/template] composites. For instance, with a Ca₃(PO₄)₂.xH₂O/ceramic salt weight ratio ranging from 0 to 1, the specific surface areas of Nb₂O₅ and Ta₂O₅ were gradually enhanced of 48–166 m²/g and 5–84 m²/g, respectively. The pore volumes were increased as well. The use of the eco-friendly tricalcium phosphate material (Ca₃(PO₄)₂.xH₂O) as template in the hard-templating approach may be suitable and efficient in the aim of synthesizing materials with enhanced surface properties.     

SiO2含量对Ti/IrO2-Ta2O5-SiO2析氧阳极的电催化活性及稳定性的影响

以钛板为基体,通过热分解H2IrCl6,TaCl5和H2SiO3的混合涂液制备了Ti/IrO2-Ta2O5-SiO2阳极,研究了SiO2含量对Ti/IrO2-Ta2O5-SiO2阳极电催化活性及稳定性的影响.结果表明:掺杂SiO2后Ti/IrO2-Ta2O5-SiO2阳极电催化活性降低;适量SiO2可以提高Ti/IrO...     

Oxygen-defects modified amorphous Ta2O5 nanoparticles for solar driven hydrogen evolution

An oxygen-deficient amorphous Ta₂O₅ nanoparticle photocatalyst was synthesized by a solvothermal method and thermal annealing in Ar atmosphere. The as-prepared Ta₂O₅ photocatalysts possess improved hydrogen evolution activities compared to pristine Ta₂O₅ and commercial Ta₂O₅ under the irradiation of simulated solar light. Therein, Ta₂O₅ nanoparticles annealing at 400 °C exhibit the most preferable catalytic performance of 10.67 μmol g^?1 h^?1. The enhanced performance can be attributed to the existence of oxygen defects in the samples, which can facilitate the separation and migration of photogenerated carriers thereby reducing the probability of recombination.     

Ta_2O_5掺杂Bi_2O_3–ZnO–Nb_2O_5陶瓷的晶体结构、结晶化学及介电性能

采用固相反应法制备Bi1.5ZnNb1.5–xTaxO7陶瓷,研究了不同掺杂量Ta2O5对Bi2O3–ZnO–Nb2O5陶瓷相结构、晶体化学特性和介电性能的影响。结果表明:当x≤0.1时,样品均保持单一的立方焦绿石结构(α–BZN)。通过对样品结晶化学计算发现,随着Ta2O5掺杂量的增加,晶格常数a逐渐减小,结晶化学参数键价和AV(O')[A4]增大,AV(O)[A2B2]减小,48f(O)坐标ξ增加。在组成样品晶体结构的多面体中,由6个48f(O)组成的八面体结构(BO6)逐渐变得扭曲,而6个48f(O)和2个8b(O')组成的六面体结构逐渐变得规则,向正立方体结构变化。室温下样品的介电常数和损耗随Ta2O5掺杂量的增加而减小,弛豫度逐渐减小。     

Electrocoagulation/electroflotation of real printing wastewater using copper electrodes: A comparative study with aluminum electrodes

Most studies investigated electrocoagulation/electroflotation process (EC/EF) using either aluminum or iron electrodes. The main aim of this study is to investigate the performance of EC/EF to treat printing wastewater under various experimental conditions using copper electrodes. The effects of several variables, including different electrode materials (copper and aluminum), different current densities, electrolysis time, and spacing between electrodes on the removal efficiency of various parameters were investigated. The results showed that the maximum removal efficiencies for COD,TDS, and oil and grease were obtained when using a copper electrode. The maximum removal efficiencies were obtained at a gap distance of 4 cm.