Ceramics International最新文献

In recent years, numerous studies have focused on the use of mixed ionic-electronic conducting oxides for coupled oxygen separation and catalytic reactions in membrane reactors. A promising strategy for the efficient fabrication of oxygen separation membranes involves modification of the membrane surface via exsolved metal nanoparticles decoration. Here, we present a detailed characterization of the structural and transport properties of a novel membrane material La_0.4Sr_0.6Fe_0.95Nb_0.05O_3−δ (LSFNb5). The exsolution of Fe nanoparticles was observed after heating of LSFNb5 in a reducing atmosphere (5% Н₂/Ar) and was confirmed by X-ray diffraction analysis, Mössbauer spectroscopy, high-resolution transmission electron microscopy and X-ray photoelectron spectroscopy. The formation of Fe nanoparticles on the surface of LSFNb5 hollow fiber membrane in the reduction process leads to the enhancement of oxygen fluxes and reduces the apparent activation energy. Kinetic parameters for oxygen transport through LSFNb5 hollow fiber membrane estimated using two different models, are in good agreement with the experimental results. Furthermore, LSFNb5 hollow fiber membrane demonstrates stable performance both before and after surface treatment.

The profound contamination of reservoirs triggered by industrial dyes and the growing phenomenon of antibiotic-resistant bacteria present substantial risks to both the environment and human health. Conventional approaches to water treatment and microbiological disinfection can frequently become ineffective, expensive, and detrimental to the environment, and this issue underscores the need for novel materials that possess refined photocatalytic and antibacterial characteristics that thrive efficiently in a setting of visible light. An innovative nanostructured nanocomposite, Mo-CeO₂@C, was synthesized using a green chemistry method coupled with Mo-CeO₂ nanoparticles and pristine CeO₂. The impact of Ce, Mo, and carbon-based nanocomposites has been validated by leveraging XRD, FTIR, UV-vis spectra, and FE-SEM/EDX. The sunlight-mediated photodegradation performance of carbon-based nanocomposite exhibited a superior photodegradation efficiency of 99.5%, higher than others. The photocatalytic activity of M.B. dye concentration, catalyst dosage, scavenger test, and recyclability were also conducted, which confirm the optimal catalyst loading of 20 mg, dye concentration 40 ppm, and pH 8 with reusability up to six^th cycles. The carbon-coated doped nanocomposite displays superior antibacterial efficacy against gram-positive S. aureus, gram-negative E. coli, and P. vulgaris bacteria in comparison to CeO₂ and Mo-doped CeO₂. This may be attributed to the combined effects of the generation of reactive oxygen species (R.O.S.) and the intrinsic characteristics of the dopant and carbon matrix. The results of our research emphasize the potential of carbon-based nanoparticles as versatile agents in the realms of environmental rehabilitation and biomedical research. These nanoparticles provide a method to achieve more efficient and resilient solutions in these areas.

In this study, NaMg_1-xMn_x(PO₃)₃ (0.00 ≤ x ≤ 0.0625) ceramics with low dielectric constant were prepared via the solid-state reaction method. The effects of Mn²⁺ substitution on the microstructure and dielectric properties (at microwave and terahertz frequencies) of the NaMg(PO₃)₃ ceramics were studied by means of the Rietveld refinement, morphology, and ionic polarizability analysis. It is obtained that the NaMg_0.0975Mn_0.025(PO₃)₃ ceramic sintered at 880 °C for 4 hours exhibited optimal dielectric properties at microwave frequencies, where ε_r = 4.585, Q×f = 48,313 GHz (@17.228 GHz), and τ_f = -40.83 ppm/°C. The Q×f and τ_f values were changed by 74.2% and 27.8%, as compared to the values of 27,728 GHz and -56.52 ppm/°C for the pure NaMg(PO₃)₃ ceramic, respectively. For terahertz frequencies (0.2 ∼ 1.0 THz), the ε_r values were decreased to 3.79 ∼ 3.98, and the tanδ values were between 0.0203 and 0.1152. All the experimental results indicate that this system exhibits great potentials both at microwave and terahertz frequencies.

Nano tungsten carbide (WC) was synthesized using loose yellow tungsten oxide (WO3) rods, which were derived from violet tungsten oxide (WO2.72) through calcination in dry oxygen. The WO3 rods were then subjected to ball milling with carbon black, followed by carbothermal reduction and carbonization. Unlike conventional methods such as hydrogen reduction or carbothermal reduction, this technique avoids the formation of hydrated tungsten oxides and addresses challenges related to precise carbon control and matching. This streamlined procedure produces nanoscale tungsten carbide particles approximately 150 nm in size, showing great potential for future industrial applications.

Ti₃SiC₂ MAX phase ceramic has effectively enhanced the oxidation resistance of C/SiC composites. However, there is still a need for a numerical ablation model that can analyze the ablative behavior of 2D C/SiC composites. To address this, an efficient, phenomenological multi-scale ablation model, including the thermal property theoretical model, oxidation, decomposition, and sublimation ablation models, is established for revealing the effect of Ti₃SiC₂ on the ablation resistance of the 2D C/SiC composite. The ablative behavior is evaluated using the continuous-wave laser with different laser power densities as the heat source and used as a basis for numerical model verification. The results show that the Ti₃SiC₂ MAX phase ceramic can improve the ablation resistance of the 2D C/SiC composite under different laser power densities. The ablation roughness is reconstructed through the mesoscopic geometry structure and maximum/minimum ablation depth. The numerical model can analyze the effect of the mesoscopic geometry structure parameters on the ablation behavior. The model can provide a predicting method for the quantitative ablative calculation of 2D C/SiC and matrix-modified composites.

This research investigated the application of municipal solid waste incineration fly ash (MSWIFA), municipal solid waste incineration bottom ash (MSWIBA), and construction waste residue (CWR) as raw materials for the comprehensive conversion into municipal solid waste ceramics employing the SiO₂-Al₂O₃-CaO-MgO (8wt.%) phase diagram. This study aimed to evaluate the influence of the addition of MSWIFA and sintering temperature on important ceramics properties, including linear shrinkage, water absorption, sintering range, and flexural strength. Additionally, relationships were established among these physical parameters using Pearson's correlation coefficient. The thermal behavior of the mixture was analyzed through automatic slag melting point tester and TG-DSC techniques. Furthermore, characterization of the crystalline phase transition and microstructure of sintered samples was performed by XRD, Factsage, and SEM. The results showed that both the addition of MSWIFA and the sintering temperature significantly influenced the crystal phase composition of the sintered ceramics. Moreover, the addition of MSWIFA and the sintering temperature had a significant influence on the pore structure of the ceramics. These ceramics exhibited exceptional properties, such as the extremely low water absorption rate of 0.08% and the remarkable flexural strength of 124.78 MPa. Ceramics performance indicators were far higher than the requirements of China's national standard GB/T4100-2015. The sintering range had the capability to attain 30 °C, guaranteeing the feasibility of practical manufacturing processes. Furthermore, leaching concentration tests conducted on additive-free ceramic samples reveal a low risk of heavy metal contamination, as the heavy metals were effectively solidified within the crystalline and amorphous phases of the ceramics. The comprehensive utilization of MSWIFA, MSWIBA, and CWR for the production of fully solid waste ceramics not only yields cost reduction benefits but also promotes efficient utilization, presenting a feasible and highly promising approach to sustainable waste management.

The development of Ga-doped Zinc Oxide (GZO) films from nontoxic, abundant elements using a cost-effective and scalable approach is crucial for the profitability and sustainability of thermoelectric applications. Challenges in formulating GZO film inks have led to extensive experimentation to enhance their thermal, structural, mechanical, and room-temperature thermoelectric properties by adjusting ink concentration and annealing treatment. Increasing the GZO nanoparticle concentration reduced the melting temperature and crystallinity, whereas annealing at 200 °C decomposed the polyethylene oxide (PEO) binder. TEM analysis revealed the polycrystalline structure of the GZO nanoparticles and their interaction with the binder, while XRD patterns confirmed the characteristic peaks of the GZO films; annealing effectively eliminated the PEO diffraction peaks. The GZO films from the concentrated 1.24M ink exhibited minimal grain growth, reduced lattice strains, uniform elemental distribution, and enhanced surface texture and conductivity, which were further improved by annealing. Increasing the GZO nanoparticle concentration facilitated the formation of a conductive network, while annealing enhanced the conductivity by promoting the formation of a cohesive, interconnected network through impurity removal, nanoparticle redistribution, and coalescence. Consequently, the annealed 1.24M film demonstrated the highest nanohardness of 791 MPa and a thermoelectric power factor of 1.78 nW/m∙K² at room temperature, which were attributed to enhanced electrical conductivity and Seebeck coefficient through concentration and annealing synergies.

To improve the mechanical properties of Ni625 coatings, different contents of Nb powder and Ni-coated graphite particles were added to Ni625 powder for in-situ generation of NbC particles. The effects of different NbC contents on the microstructure, hardness, wear resistance and corrosion resistance of Ni625 coatings were investigated. The results show that the highest XRD phase diffraction peaks of NbC in the coating are obtained with the addition of 15% ( Nb 9.9%, Ni-coated graphite particles 5.1%), and the coating exhibits a hardness of 441.9 HV, which is 1.53 times greater than that of the coating with the addition of 0%. Furthermore, the wear coefficient (μ) of the coating is 0.4804, and the wear volume is 0.0042 mm³, representing a reduction of 23.5% and 64.1%, respectively, in comparison to the coating with 0% additive. However, the coating with an addition of 20% does not generate more NbC phase, and the hardness and wear resistance are not further improved. The coating with an addition of 10% has the best corrosion resistance, with a corrosion current density of 2.1829E-10 A/cm². Further additions do not result in an enhanced corrosion resistance of the coating. Therefore, appropriate amount of in-situ generation of NbC within the Ni625 coating during the laser cladding process can effectively enhance the mechanical properties of the Ni625 coating.

Metal doping is an efficient approach to improve H₂S gas sensing performances, but the metal-doped NiO is still faced poor recovery capability at low working temperature. Herein, Co-doped NiO@g-C₃N₄ heterocomposites were constructed firstly via a simple solid phase reaction. Texture characterizations indicate that Co-doped NiO@g-C₃N₄ heterocomposites with the architecture of hierarchical microspheres show high specific surface areas and rich surface oxygen vacancies. The gas-sensitive measurements exhibit that the response value of the heterocomposites with g-C₃N₄ content of 30 wt% (Co-NiO@g-C₃N₄-3) increases to 45 toward 20 ppm H₂S gas at 172 °C, which is about 1.8 times of Co-NiO (23), as well as response/recovery times decreased to ca. 100/130 s. Besides, excellent repeatability, stability and selectivity of Co-NiO@g-C₃N₄-3 sensors are obtained. The improved H₂S gas sensing performances of Co-NiO@g-C₃N₄ heterocomposites is mainly contributed to the formation of nano-heterojunctions, which promotes electron accumulation at nano-heterojunctions near Co-NiO, facilitates O₂ molecules adsorption on the material surface and accelerates the resistance change of the sensors, resulting the enhanced gas sensing performances.