Ceramics International最新文献

The influences of temperature and compositions (TiO₂ and CaO/SiO₂) on thermodynamics properties and structural evolutions of TiO₂-CaO-Al₂O₃-MgO-SiO₂ slags were investigated in this work. The slag viscosities increased with decreasing the temperature and declined with adding TiO₂. With the raising of CaO/SiO₂ ratio, the viscosity decreased under high temperatures, while it increased with the temperature further decreased lower than 1420 °C. The enthalpy change of the slag increased with raising the temperature as well as the TiO₂ content and reduced with the CaO/SiO₂ ratio increasing. Both the liquidus temperature and break point temperature of the slags decreased with adding TiO₂ and increased with raising the CaO/SiO₂ ratio. Temperature had a significant effect on slag structure evolutions, which decreased the slag polymerization degree. With adding TiO₂ and CaO/SiO₂ ratio in slags, the slag structure stability was weakened by increasing the amount of simpler silicate and TiO₆ units and reducing the proportion of complex Ti-O units. Both the temperature and compositions (TiO₂ and CaO/SiO₂) depolymerized the slag structure to decline the viscosity.

Silicon carbide (SiC) ceramic membranes are highly sought-after for their exceptional properties including high temperature resistance, corrosion resistance, good hydrophilicity, high flux, and high mechanical strength. However, achieving stable regulation of high solid content SiC slurries for membrane preparation remains a significant challenge. This study presents a novel approach to stabilize the dispersion of high solid content SiC slurries by controlling parameters such as solid content, pH, ball milling time and spray coating parameters. Furthermore, the impact of different milling durations on SiC particle size and membrane performance is systematically investigated, establishing, for the first time, a direct correlation between milling time and particle size. The investigations reveal that prolonged ball milling, specifically 18 hours, results in a notable reduction in membrane pore size by approximately 40%, accompanied by a remarkable enhancement in retention performance, as evidenced by a substantial increase in the average retention rate for 500 nm fluorescent microspheres from 54.61% to 98.89%. This study not only offers a practical method for the stable preparation of ceramic slurries, but also provide important reference for membrane morphology control and pore size regulation. These insights hold significant promise for advancing SiC membrane technology in applications such as wastewater treatment and resource recovery.

In the present study, the effect of precursor concentration for WO₃ deposition by AACVD method was investigated. At the outset, H₂WO₄ was synthesized as the precursor for the deposition process. In the next step, H₂WO₄ solutions used in the AACVD process, with concentrations of 0.1, 0.5, and 1 M, were evaluated using a static wettability test. CV test revealed that at a concentration of 0.5 M, a higher number of charge carriers were involved in the redox process. CA and EIS tests were also employed to measure the impact of concentration on the electrochemical properties of the coated samples. Based on these findings, the concentration of 0.5 M was identified as optimal. Subsequently, Triton X-100 was added to the solution as a surfactant, and the deposition process was carried out. All the aforementioned tests were also conducted on the 0.5 M + Triton sample. Microstructural studies showed that the addition of Triton X-100 to the 0.5 M solution significantly improved the uniformity of the deposited tungsten oxide films. Based on optical measurements, the 0.5 M + Triton sample exhibited the optimal optical modulation (55.66%), and coloration efficiency (40.37 cm²C^-1) at the wavelength of 633 nm.

(1-x)Na_0.5Bi_0.5TiO₃-xBiFeO₃ (NBT-BFO) is a system with a composition-induced transition from relaxor to ferroelectric. Upon quenching, 0.4NBT-0.6BFO obtain a T_d of 640 °C and d₃₃ of 56 pC/N. However, the quenching treatment also causes the reduction of resistivity, which is unfavorable for high-temperature piezoelectric ceramics. The aim of this study is to restrain quenching-induced decline of resistance in NBT-BFO ceramics by doping a small amount of BiAlO₃ (BA). For unquenched NBT-BFO-BA, with increasing BA content, the piezoelectric coefficient (d₃₃) decreases slightly, while the resistivity increases. After quenching, both d₃₃ and the depolarization temperature (T_d) increase, but more importantly, the resistivity of quenched NBT-BFO-BA is comparable with that of the unquenched samples. This phenomenon is not observed in other quenched samples, and the reason is attributed to the defect dipoles caused by BA. Besides, the enhanced piezoelectric properties and the resistivity can be retained after annealing the quenched samples at 400 °C for 4 h. Thus, this work implies the potential application of NBT-BFO based piezoelectric ceramics at elevated temperatures.

In this study, a solid-state reaction was employed to synthesize SrY₂O₄: Sm³⁺, SrY₂O₄: Eu³⁺ and SrY₂O₄: Sm³⁺/Eu³⁺ phosphors. An intriguing redshift phenomenon from charge transfer band (CTB) edge was investigated for single-band ratiometric (SBR) thermometry applications. The phosphors synthesized exhibited an orthogonal CaFe₂O₄ structure with Pnam(62) space group. The Y³⁺ sites from host lattice were most likely to be replaced by Sm³⁺/Eu³⁺ ions. The sample of SrY₂O₄: 0.03 Sm³⁺/0.3Eu³⁺ showed a large degree of agglomeration with elongated particles, having an average size of approximately 4 μm. The energy bandgap decreased due to increased surface imperfections, resulting in enhanced defect level concentration. The dipole-dipole interaction could be used to explain energy transfer (ET) of Sm³⁺-Sm³⁺ and Sm³⁺-Eu³⁺. Furthermore, the ET efficiency of Sm³⁺→Eu³⁺ in Sr₂YO₄ reached 77.7%. The sample exhibited a good thermal stability (90.956%@423 K) with E_a of 0.31 eV, which was an important parameter for broadening thermometry range. A thermometry strategy utilized this redshift phenomenon from CTB edge with anti-thermal quenching behavior and other peaks or bands with thermal quenching was therefore proposed. The high Sr value of 1.533% K^-1@298 K provides a great potential for optical thermometry application, contributing significantly to the advancement of single band ratiometric thermometry technologies.

The rapid development of additive manufacturing techniques enables the preparation of SiC ceramics with complex configurations; however, the high sintering temperature and defects-control are still great challenges during processing. Thus, SiC ceramics were prepared by digital light processing followed by liquid phase sintering using Al₂O₃-Y₂O₃ additives in this study. The photopolymerization of the SiC slurry, microstructures and mechanical properties of the sintered ceramics were investigated. The Al₂O₃-Y₂O₃ additives enhanced the curing ability of the photosensitive SiC slurries by reducing the absorbance and scattering of UV light. The liquid phase accelerated the densification of the ceramics by particles rearrangement and interfacial bonding. Thus, the flexural strength of the ceramics increased from 41.0 MPa to 62.8 MPa with sintering temperature increasing.

Lithium barium borophosphate glasses doped with Er³⁺ rare earth ions are reported in terms of their physical, optical, structural, and thermoluminescence (TL) properties in this study. The melt quenching method was used to synthesize the glasses with varying concentration of the dopant (0.0, 0.2, 0.4 0.6, 0.8 and 1.0 mol%). A thorough analysis of physical characteristics, including their variation with erbium oxide, has been conducted. The amorphous phase of the as-quenched samples has been validated through X-ray diffraction patterns, while Fourier transform infrared spectroscopy confirmed the existence of different structural groups. UV-Vis-NIR spectroscopy at wavelengths ranging from 200 to 1100 nm has been utilised to investigate various optical properties. In the gamma dose range of 50 Gy to 10 kGy, the glass sample with 0.6 mol% of erbium concentration (LBPEr0.6) showed the maximum integrated TL intensity with an optimized heating rate of 5 ºC/s and annealing temperature of 400 ºC. The deconvolution of TL glow curves was done using the R-package "tgcd: Thermoluminescence Glow Curve Deconvolution" by employing the Kitis general order kinetics model. Chen's peak shape approach has been used to calculate the trapping parameters, including order of kinetics (b), shape factor (μ_g), frequency factor (s), and activation energy (E). The ideal thermoluminescence dosimeter characteristics showed that LBPEr0.6 glass has outstanding linearity, excellent sensitivity, minimal fading and good reproducibility over six cycles.

Fluoride ion batteries (FIBs) are emerging as a promising alternative to conventional lithium-ion batteries, primarily because of their high theoretical energy density and environmentally sustainable characteristics. For the development of a high-performance solid-state fluoride ion battery, an engineered electrolyte is crucial. As the synthesis technique impacts the phase, microstructure, and morphology of the materials, a unique and facile sonochemical route is employed for the first time herein for synthesizing Tin (II) fluoride as a solid electrolyte. The XRD investigations have indicated the formation of the α-SnF₂ phase with a monoclinic structure, and space group C2/c. The particle size of SnF₂ synthesized using 225 W and 325 W power of probe sonicator is found to be 2μm and 0.8μm respectively, as revealed by Scanning Electron Micrographs. SnF₂ prepared with 325 W ultrasonic power has exhibited the maximum ionic conductivity of value 3.4× 10^-4 S/cm at room temperature, with a significant enhancement regarding the values reported so far. The anionic transport number of the electrolyte estimated at room temperature using the combined AC-DC technique is found to be 0.96, indicating fluoride ion conduction.

Layered double hydroxides (LDHs) represent a category of two-dimensional layered intercalation materials, showing significant potential as electrode materials for the production of high-energy-density supercapacitors due to their tunable composition, ease of synthetic modification, and low cost. Here, we constructed alkali-etched NiAl LDH-OH nanosheets/Ag nanoparticles (NPs) composite material (Ag@NiAl LDH-OH) for high-performance supercapacitors through a simple solvent-thermal reaction. The alkali treatment is employed to selectively etch some Al³⁺ ions, generating cation vacancies as active sites for energy storage. Additionally, under the simultaneous influence of strong alkalis and vacancies, the interlayer spacing of LDHs expands, aiding in the promotion of interlayer ion mobility. Meanwhile, the decoration of silver nanoparticles ensures excellent electron conductivity in the NiAl-LDH-OH nanosheets, thereby facilitating improved utilization of the active substance and achieving outstanding rate performance. The Ag@NiAl LDH-OH electrode, when prepared, demonstrates a significant increase in specific capacitance, reaching 1790 F g⁻¹ at a current density of 1 A g⁻¹. This represents approximately 7 times the specific capacitance of the pristine NiAl LDH electrode, with a capacity retention of 79 % even under a high current density of 20 A g⁻¹. Moreover, the assembled asymmetric supercapacitor (ASC) attains a maximum energy density of 138.25 Wh kg⁻¹ at a power density of 700 W kg⁻¹, maintaining 81 % of its initial specific capacitance after 20000 cycles. This research introduces novel pathways for advancing high-energy-density SCs.

Ensuring a consistently high-strength connection in superalloy components of space shuttles from 25-1200 °C is essential yet challenging. To achieve the objective, we developed an adhesive using silicon-boron modified phenolic resin (Si-BPF) as the matrix and inorganic fillers as additives. The continuous Si-O-Si-O-B-O-B skeleton endowed the Si-BPF with excellent thermal stability. In addition, the inorganic fillers inhibited the thermal decomposition of Si-BPF. The generation of low-melting-point glass phases compensated for the defects in the adhesive. Therefore, within the “300-600 °C weak strength interval”, the synergistic effect of Si-BPF and inorganic additives increased the adhesive strength to 17.26 MPa. The formation of intermetallic compounds and the ceramization of the adhesive resulted in a gradual increase in the bonding strength of the composite adhesive with increasing temperature, reaching 34.23 MPa after 1200 °C. The adhesive enabled high-strength bonding for superalloys throughout the wide temperature range, enhancing the application of superalloy components in space shuttles.