Ceramics International最新文献

With the increasing requirements from toxic and hazardous gas detection technologies, WO₃-based gas sensors have garnered tremendous interest on account of their low operating temperatures, good cycling stability, and short response/recovery time. So far, considerable progress has been made in the design and preparation of different architectures of WO₃. The sensing mechanism of WO₃-based gas sensors is relatively complex. To further optimize the capabilities of WO₃-based gas sensors, the influencing factors of the sensing mechanism need to be deeply understood to seek more effective enhanced strategies. This review probes the application of WO₃-based sensors for various dangerous gases and contrastively analyses the sensing behavior of WO₃ in detail. In addition, we pay special attention to the interfacial interaction pathways between the sensing material and the target gas. Nowadays, more efforts are being made to strengthen the sensing properties of WO₃-based materials so that they can be used in more smart demanding and complex environments. The authors focus on four approaches, namely, morphology control, hybridization, defect engineering, and photoactivation, for enhancing gas sensors and providing a comprehensive study of WO₃ for gas-sensing applications. Finally, we discuss the current problems and improvement methods and provide an outlook on the development trend of WO₃-based gas sensors.

In the conducted research, a one-step hydrothermal synthesis of pure and titanium-doped tin dioxide quantum dots is elaborated upon, with a thorough analysis of their structural, optical, morphological, and photocatalytic properties undertaken using advanced analytical techniques. Through X-ray Diffraction XRD, the crystalline nature and phase purity of the tetragonal structures of SnDs were confirmed, with the crystallite sizes measured at 3.0 nm for SnD1 and 7.66 nm for SnD2, following treatments at 240°C and 300°C, respectively. The structural integrity of SnO₂ was maintained despite titanium doping. FTIR spectroscopy verified the existence of specific vibrational modes indicative of surface hydroxyl groups. HRTEM images revealed the spherical morphology of particles, with diameters of 3.5 nm for SnD1 and 9.1 nm for SnD2. Optical band gaps, determined through UV-DRS, ranged from 3.33 eV in SnD1 to 3.47 eV in SnDTi2. The photocatalytic degradation of Congo Red dye under xenon lamp irradiation was quantitatively assessed; notably, SnD1 exhibited a 23% higher rate constant compared to SnD2, attributed to its smaller particle size and a 31% greater surface area. Doping with 4% Ti in Sn_0.96Ti_0.04O₂ more than doubled the degradation rate compared to a 6% Ti doping in Sn_0.94Ti_0.06O₂. Furthermore, the generation of hydroxyl radicals was significantly enhanced, showing an increase of approximately 220% for SnD1 and 80% for SnD2. The capability of these nanomaterials to reduce the chemical oxygen demand of industrial organic pollutants to within regulatory limits under solar irradiation was documented, with SnD1 maintaining its photocatalytic efficiency over seven cycles of reuse. In the photocatalytic degradation rate of Congo Red dye, which was 23% higher for SnD1 compared to SnD2, and the threefold increase in the degradation rate for SnDTi1 compared to SnDTi2. An economic assessment, based on electricity tariffs in Saudi Arabia, highlighted the cost-effectiveness of SnD1, which ranged from 26.93 to 30.36 USD per breakdown cost of the photodegradation process, showing it to be less costly than SnD2. Conversely, SnDTi1 was found to be more economical than SnDTi2, with costs ranging from 26.67 to 33.09 USD. Collectively, the results emphasize the outstanding photocatalytic performance and cost-efficiency of SnDs, reinforcing their potential as sustainable solutions for the treatment of industrial wastewater. Additionally, the antibacterial efficacy of these materials against a range of bacteria, yeast, and fungi was investigated and substantiated.

The lightweight design and load-bearing capacity of underwater vehicles remain perennial focal points. Ceramic lattice structures (CLSs) offer significant weight reduction while maximizing structural strength; however, their inherent brittleness poses a limitation. To optimize the performance of CLSs for underwater vehicle applications, a biomimetic Al₂O₃/phenol-formaldehyde (PF) resin composite structure (APCS) was proposed and fabricated by infiltrating additive-manufactured Al₂O₃ lattice structures (ALSs) with PF. Comprehensive assessments of the quasi-static mechanical properties were conducted using both experimental and simulation methods. The specific compressive strength and specific energy absorption of the APCSs under quasi-static compressive loading exhibited remarkable improvements, with the maximum values achieved from the body-centered cubic (BCC)/PF structure increasing by ∼15.23 and ∼307.93 times, respectively. In contrast to ALSs, the failure process of APCSs was gradual, with the confining pressure introduced by the PF promoting transverse crack propagation and layer-by-layer failure, thereby strengthening the ceramic lattice. Toughing mechanisms (i.e., crack arrest, crack deflection, and branching) were also observed in the APCSs. Furthermore, the simulation results aligned well with the experimental results, providing an in-depth analysis of internal damage and crack propagation. The improvements introduced by the composite structure in this study provide a reliable approach for obtaining lightweight and strong materials, thereby accelerating the application of ceramic-based materials in underwater vehicles.

This research aims to broaden the scope of self-lubricating wear-resistant coatings for applications in diverse industries such as automotive, metallurgy, power, and aerospace. Employing laser cladding technology, we successfully fabricated high-performance self-lubricating ceramic composite coatings. A comprehensive investigation was conducted to understand the inhibitory effect of Cu on the thermal decomposition of MoS₂, and the study systematically explored the relationship between powder composition, coating structure, and organizational properties. The mechanisms behind friction reduction and wear resistance were unveiled, shedding light on the formation of the MoS₂ self-lubricating protective film. Research findings reveal that during the laser cladding process, Cu and Ni undergo solid solution, resulting in the formation of the Cu-Ni alloy phase and crystal refinement. The MoS₂ aggregation area exhibits a fine dendritic structure, while the dispersion area showcases coarse dendritic and cellular crystals. The addition of Cu and MoS₂ influences the content of the M_xC_y phase and the thermal decomposition of MoS₂. The incorporation of Cu increases the average coating hardness, whereas MoS₂ addition decreases it; nevertheless, the Cu/MoS₂ coating hardness is enhanced by at least 6.4%. Cu significantly improves the coating's wear resistance, with a relatively smaller impact on friction reduction. MoS₂ functions as a friction-reducing phase during wear, effectively preventing the peeling of hard phases and reducing the friction coefficient. Cu is uniformly distributed in the coating, experiencing solid solution strengthening, reducing adhesive region areas, and minimizing wear debris generation. MoS₂, although unevenly distributed, forms intermittent lubricating films on the surface. The lubricating film of the Cu/MoS₂ coating remains stable, preventing mutual contact of the friction surface and concurrently reducing the friction coefficient and wear amount. While the study successfully prepared a self-lubricating ceramic coating with excellent wear resistance, some surface quality defects persist. Further optimization of the preparation method was achieved through ultrasound-assisted technology.

Uneven micron-sized pores on the surface of the polycrystalline alumina (Al₂O₃) substrates can affect their performance as electrical insulating plates. In this study, we investigated the sealing of these pores with amorphous Al₂O₃ films deposited via atmospheric chemical vapor deposition. Furthermore, we conducted annealing treatments on the samples. The color change of the deposited Al₂O₃ films was investigated using the Commission Internationale de I’Eclairage color space. Notably, the deposited films initially changed the sample color from white to orange or brown. However, increasing the annealing temperature and duration reversed this discoloration effectively and restored the original white (colorless) appearance of the sample. We measured thermal conductivity using the flame flash method with the H₂-O₂ flame to assess the influence of sealing. While the unsealed substrate exhibited a thermal conductivity of 4.66 W/mK in the range of 400–500 °C, the annealed and flattened Al₂O₃ film deposited on the substrate maintained a comparable thermal conductivity of 4.67 W/mK within the same temperature range. This finding demonstrates that our sealing method successfully filled the pores while having minimal influence on thermal conductivity, which is a crucial property for electrical insulation applications.

The structural, microstructural, dielectric, optical, ferroelectric, and magnetic properties of cobalt doped barium calcium titanate (BCT) (Ba_0.80Ca_0.20Ti_1-xCo_xO₃ with x =0.000, 0.005, 0.010, 0.015, and 0.020) ceramics have been reported in this paper. The ceramic samples were prepared by the conventional solid-state reaction method. For all of the prepared samples, the tetragonal structure with the space group P4mm has been confirmed using the refinement method through rietveld refinement of X-ray diffraction patterns. Field Emission Scanning Electron Microscopy (FESEM) micrographs revealed that the average particle size exists in micrometre range (0.3-0.8) μm. Optical studies revealed a gradual decrease in the energy bandgap from 3.31 eV to 2.71 eV with increasing doping concentration. A decreasing trend was observed in the dielectric characteristics of the material with changing frequencies at room temperature. Ferroelectric (P-E loops) analysis displayed an increase in both remnant polarization and maximum polarization of the ceramic with the increasing applied electric field. The highest value for the energy storage efficiency (η) was calculated to be 20.51%. Magnetic analysis conducted at room temperature revealed the enhancement in ferromagnetism with the increase in doping concentration.

A series of (Mg_1-xZn_x)₃(PO₄)₂ (x = 0.02-0.10) microwave dielectric ceramics were fabricated by the solid-state reaction method and investigated in terms of crystal structure, chemical bond properties, and dielectric properties were analyzed. The XRD data indicates that (Mg_1-xZn_x)₃(PO₄)₂ samples belong to the monoclinic crystal with P2₁/c space group and no detectable secondary phases. The Rietveld refinement was employed to obtain crystal parameters. In addition, the results of chemical bond properties reveal that the lattice energy and ionicity of Mg(2)-O(3) bonds play a primary effect on the dielectric loss and dielectric constant, respectively. The bond energy of Mg(l)-O(2) bonds plays a dominant role in thermal stability. The far-infrared spectroscopy was employed to explore the intrinsic dielectric parameters, and the results showed that peaks below 400 cm^-l contributed 78.9% to ε′ and 99.1% to ε″. The Raman data demonstrated that the Raman shift and FWHM exhibit an important influence on Q × f. The optimal performance was achieved in (Mg_0.94Zn_0.06)₃(PO₄)₂ ceramics: ε_r = 5.00, Q × f = 84,674 GHz, τ_f = -59.98 ppm/°C.

The present research article demonstrates the dispersion of boehmite (BHM) nanoparticles into sericin (SER) from silk industry waste with polyvinyl alcohol (PVA) to enhance the optical, mechanical, thermal and electrical characteristics of PVA/SER blend nanocomposites prepared by a simple green synthesis. Techniques such as Fourier-transmission infrared spectroscopy (FTIR), X-ray diffraction (XRD), UV visible spectroscopy, field emission scanning electron microscopy (FE-SEM), high-resolution transmission electron microscopy (HR-TEM), differential scanning calorimetry (DSC) and thermogravimetry (TGA) were carried out for the characterization of the prepared composites. XRD revealed the increased crystallinity of the polymer blend by the reinforcement of BHM. The existence of intermolecular interactions in the blend composite was confirmed by FTIR and UV spectroscopy. The optical bandgap energy of the biopolymer blend decreases with the inclusion of BHM. The SEM and HR-TEM confirmed the homogeneous dispersion of BHM in the blend at 5 w% loading. The glass transition temperature and thermal stability of the blend nanocomposites were significantly improved by the inclusion of BHM was deduced from DSC and TGA. The dielectric constant and AC conductivity were remarkably increased with the reinforcement of nanoparticles. The activation energy obtained from AC conductivity decreased with the temperature. The mechanical properties of the blend nanocomposites (hardness, elongation, tensile strength and Young’s modulus) were greatly increased in presence of BHM. The 5 wt% sample has the highest tensile strength, Young’s modulus, dielectric constant, AC conductivity and optical properties, allowing it to be used to make optoelectronic devices with better charge-storing capacity and flexible-type electrochemical gadgets.

Recently, ferroelectric memory utilizing hafnium oxide has emerged as an attractive option compared to existing memory technologies, primarily due to its scalability and energy-efficient advantages. Among them, hafnium zirconium oxide (HZO) is examined for its short-term memory characteristics to achieve a reservoir computing system known to exhibit remarkable polarization properties, being able to switch between distinct polarization states under the influence of an electric field. These unique properties are of utmost importance in ferroelectric memory applications, where they play a pivotal role in the storage and retrieval of binary data. In this study, we identify and experiment with the electrical characteristics of a ferroelectric tunnel junction (FTJ) device with a metal-ferroelectric-semiconductor (MFS) structure using TiN as the top electrode and HZO as the ferroelectric layer. Moreover, we assess the performance of the device by evaluating its maximum 2P_r (remnant polarization) and tunneling electro resistance (TER) values in different conditions of cell area. Furthermore, we analyze and show short-term memory (STM) characteristics and synaptic properties with 5 cycles of potentiation and depression under conditions of stable dynamic range by coordinating identical and incremental pulses. In the case of incremental pulses (> 95%), the MNIST pattern recognition accuracy is higher than in the case of identical pulses (> 94%). Through a sequence of procedures, the synaptic characteristics of FTJs are confirmed to assess their suitability for use as an artificial synaptic device.