Journal of the Australian Ceramic Society最新文献

In this study, basic oxygen furnace slag (BOF) was utilized as a substitute for calcium carbonate (CaCO₃) and red iron oxide (Fe₂O₃) in the production of frit, which serves as the precursor material for glass-ceramics. Two different raw material batches for SiO₂-Na₂O-B₂O₃-CaO-F frit were prepared. The batches underwent a melting-quenching process and were classified as frit (F-STD) consisting of 100 wt% commercial raw materials and frit (F-BOF) containing 4.81 wt% BOF slag in its composition. The chemical content, crystalline structure, and thermal behavior of the frits were investigated. F-STD exhibited a T_G of 599.8 °C, with corresponding T_C1 and T_C2 values of 642.2 °C and 871 °C, respectively. F-BOF displayed a T_G of 592.9 °C, along with T_C1 and T_C2 values measured at 636.6 °C and 861 °C. The powdered frits were applied on steel substrates (DC04EK) using the wet spray method and subsequently heat-treated at 840 °C for 4.5 min to obtain a reference (GC-STD) and partially sustainable (GC-BOF) glass-ceramic coatings. The phase formation, microstructure, adherence, and chemical corrosion resistance of the coatings were compared. The coatings were found to be in the optimum adhesion class, numbered 1, according to the BSI EN10209 standard. Analysis of the GC-STD, with an average bubble size of 29.12 μm, and GC-BOF, with an average bubble size of 34.2 μm, revealed fewer and larger diameter bubbles in the sustainable composition. Fluorite (CaF₂) and fluorapatite (Ca₅(PO₄)₃F) crystal phases were detected in both samples. The compatibility of BOF slag in glass-ceramic coating formulation was demonstrated by identical characteristics exhibited by GC-STD and GC-BOF.

Herein thin films of bismuth oxide are doped with iron by the thermal deposition technique under a vacuum pressure of 10^–5 mbar. The doping content varied in the range of 3.0 wt.% to 13.0 wt.%. It is found that undoped and Fe-doped Bi₂O₃ films exhibited monoclinic structure with lattice parameters of (a=7.9765;oversetcirc A,;b=7.1253;oversetcirc A,;c=4.5964;oversetcirc A) and (beta =102.203^circ) and space group (8/Lc140). Fe-doping below the solubility limit (13.0 wt %) resulted in smaller crystallites, larger strains and larger defect densities. Above the solubility limits orthorhombic Fe₂O₃ occupied 30.6% of the total phase of Bi₂O₃ films. Fe-doped Bi₂O₃ films showed lower dielectric constant value, lower electrical conductivities and larger microwave cutoff frequencies. Analyses of the ac conductivity spectra indicated that the ac conduction is dominated by the correlated barrier hopping. The increased doping level below the solubility limit decreased the density of localized states near Fermi level and increased the correlated barrier height. It is also observed that 3.0 wt% of Fe can improve the cutoff frequency from 133 to 160 GHz. The cutoff frequency spectra of pure and doped samples displayed values that suits 6G waveguides, field effect transistors, and other high-frequency applications.

To develop a novel refractory system for cleaner steelmaking and alloy smelting, Al₂O₃-MgO-CaO-Y₂O₃ materials were successfully synthesized via the solid-phase method, utilizing Al₂O₃-MgO-CaO as well as Y₂O₃ as the primary raw materials, with TiO₂ serving as an additive. The impact of TiO₂ on the sintering behavior, mechanical properties, and thermal shock resistance of the material was further investigated to elucidate its influence mechanism. The findings reveal that the addition of TiO₂ led to an increase in the volume shrinkage ratio of the samples from 23.40% to 30.14%, a decrease in bulk density from 3.11 g·cm⁻³ to 2.85 g·cm⁻³, and an increase in apparent porosity from 9.52% to 18.00%. Furthermore, the cold compressive strength of the samples decreased from 108.6 MPa to 54.64 MPa, and the residual strength ratio after three cycles of thermal shock decreased from 78.10% to 66.14%. The internal structure of the material primarily consists of MgAl₂O₄, Al₅Y₃O₁₂, and CaAl₂O₄ phases, formed at different reaction stages (initial, intermediate, and final stages). The formation conditions of these crystal phases significantly influence the microstructure and properties of the material. Upon the addition of 6 wt% TiO₂, numerous Al₂TiO₅ and Mg₂TiO₄ precipitate from the continuous liquid phase during cooling, along with partially unreacted Al₂O₃. These grains exhibit relatively small size and high content, leading to an increase in energetically mismatched grain boundaries and interfaces among the internal grains, thereby augmenting the overall structural inhomogeneity of the material. Consequently, this diminishes the mechanical property and thermal shock resistance of the materials.

In this work, Yb-doped Sr_0.95Ba_0.05Bi₂Ta₂O₉ powders were synthesized by the citric acid-assisted method. The prepared powders were uniaxially pressed and sintered at different temperatures. Structure, morphology, and dielectric properties were investigated. The use of either a 1200 °C sintering temperature or motifs for a reduction tanδ purpose. The results showed that Yb has not caused a significant change in dielectric properties at low temperatures, thus indicating its ability to reduce dielectric loss smoothly. At high temperatures, the introduction of ytterbium elements could reduce both Curie temperature and conductivity. According to Jonscher’s universal power law, the correlated barrier-hopping (CBH) model describes the AC conductivity mechanism. However, the non-overlapping small polaron tunneling (NSPT) model may be used to show that this is only possible at a specific temperature. The Arrhenius law and the CBH module provide estimates of the various energy barriers that space charges should overcome; however, these barriers get higher as the dopant concentration rises.

This study explores the synthesis and application of carbon quantum dots (CQDs)-based composite photocatalysts, including CQDs, CdS@CQDs, and Mn-doped CdS@CQDs, for the degradation of methylene blue (MB) and Reactive Black 5 (RB5) through photocatalysis. The synthesis of the photocatalysts involved a meticulous procedure utilizing olive oil as a precursor. Characterization studies employing transmission electron microscopy (TEM), X-ray diffractometer (XRD), and Brunauer-Emmett-Teller (BET) surface area confirmed the successful synthesis of the composite photocatalysts with well-dispersed nanoparticles and varying surface areas. Photocatalytic degradation experiments revealed that Mn-doped CdS@CQDs exhibited the highest degradation efficiency for both MB and RB5 under optimized reaction conditions, with pH identified as the most significant parameter, and statistical analyses supported the validity of the experimental data. Based on the results, the highest MB degradation efficiency (99.87%) was achieved at the following reaction conditions: pH = 9, catalyst amount = 0.55 g/L and initial hydrogen peroxide concentration (HPC) = 1 mM while the highest RB5 degradation efficiency (98.15%) was obtained at the following reaction conditions: pH = 3, catalyst amount = 1 g/L and HPC = 0.55 mM. Comparison with the literature showcased the competitive performance of the synthesized photocatalysts, achieving higher efficiencies with lower amounts of photocatalysts and hydrogen peroxide. Kinetic studies revealed that the first-order reaction kinetic was observed in both MB and RB5 degradation. This comprehensive investigation underscores the potential of Mn-doped CdS@CQDs as efficient photocatalysts for wastewater treatment, offering insights for future research and application in environmental remediation efforts.

This study investigated the production of ZrC-TiC composite nanopowders by SHS process in TiO₂-ZrO₂-C-Mg/Al systems. Mg and Al charge stoichiometries and composite charge stoichiometries were optimized for SHS processes. The most precise procedural stages were identified for refining the SHS product; acid concentrations were optimized for Mg usage and an innovative chemical method was developed to eliminate and/or decrease the amount of Al₂O₃ by-product, enabling the utilization of Al. Thermochemical simulations were conducted for thermodynamic evaluations (adiabatic temperature and specific heat) and characterizations were performed by XRD and SEM-EDS analysis. The findings indicated that utilizing both reductants allowed for the synthesis of ZrC-TiC-(Al₂O₃) particles that have considerable surface area and commercial purity. The outcomes demonstrated that Magnesium is a more effective reductant, yet Aluminium, also serves as a viable reductant, even though leading to an increase in process steps, but enabling in-situ formation of sinterability and toughness enhancing Al₂O₃. A novel chemical route including pre-acid leaching, NaOH fusion, water leaching, HCl leaching was identified for the synthesis of ZrC-TiC-Al₂O₃ composite powder where the amount of Al₂O₃ could be organized (according to the desired mechanical properties) by optimization.

Pumice, a porous rock resulting from the rapid cooling of tuff fragments during volcanic activity, exhibits a spongy texture and light color due to its low density. Found predominantly in Central Anatolia and Eastern Anatolia, it has drawn interest for industrial applications. This study delved into utilizing micronized pumice within the porcelain tile manufacturing process. Comparative analyses were conducted between formulations incorporating micronized pumice and the standard ceramic tile recipe. In place of feldspar, micronized pumice was introduced at concentrations of 3%, 5%, and 7%, while clay was substituted with micronized pumice at concentrations of 3%, 5%, 7%, and 10% by weight. The prepared bodies were fired in an industrial kiln at 1210 °C for 54 min, and various physical and mechanical properties were evaluated. These included viscosity, sieve residue, green strength pre-firing, firing shrinkage, water absorption, firing strength, and firing color after-firing. The results indicated that the samples incorporating micronized pumice closely matched the physical and mechanical properties of the standard porcelain tile. Phase and microstructural analyses revealed the presence of mullite and quartz phases. Notably, micronized pumice demonstrated promise as a substitute for clay or feldspar, with the optimal usage rate determined to be 7% in the porcelain tile recipe. This indicates that pumice has the potential to be an alternative raw material in the production of porcelain tiles.

Nanomaterials exhibit properties not seen in large-scale materials; therefore, they have been developed for different applications. Top-down and bottom-up approaches are used to design and fabricate composite materials. Electrostatic assembly (ESA) is a bottom-up approach to material design. In this study, SiO₂‒SiO₂ composite nanoparticles were selected as a model to demonstrate the feasibility of fabricating composite particles via ESA. In addition, researchers have been studying the fabrication of high-density Al₂O₃ (which has a theoretical density of approximately 3.95 g ml^− 1) at moderate temperatures for a long time. In this study, composite particles consisting of small Al₂O₃ particles (low sintering temperature) surrounding large Al₂O₃ particles (high sintering temperature) were fabricated via ESA. The sintered bodies of Al₂O₃ composite particles obtained at 1350 °C for 2 h had a density of approximately 3.0 g cm^− 3, which exceeded that of sintered bodies of only high-temperature-sintered Al₂O₃ (2.8 g cm^− 3).

Carbon based composite has gained interest as a photothermal conversion material for interfacial solar vapor generation towards the generation of clean water through solar– thermal conversion. In this study, successful synthesis of a carbon/ceramic composite containing sawdust hydrochar (SHC) and titanium dioxide (TiO₂) was obtained through a simple mixing method. The SHC/TiO₂ composite was characterized by scanning electron microscope (SEM), transmission electron microscope (TEM), energy dispersive X-ray (EDX), Fourier-Transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and ultraviolet–visible spectrophotometry (UV–Vis). SEM showed the simple mixing method only minimally damaged the SHC structure, while TEM revealed the integration of TiO₂ on the surface of SHC. The existence of the TiO₂ elements and various functional groups detected in the EDX, FTIR, and XPS proved the successful integration of TiO₂. UV-Vis displayed the SHC/TiO₂ had improved light absorption ability in contrast to the SHC and TiO₂. The SHC/TiO₂ based solar absorber (SHC/TiO₂–SA) was fabricated using dip-coating method and utilized for interfacial solar vapor generation in seawater desalination. The interfacial solar vapor generation was conducted outdoors with an average solar intensity of 1.15 kW/m² where the SHC/TiO₂–SA showed the highest average efficiency (76.3 ± 4.6%) and evaporation rate (1.29 ± 0.15 kg/m².h). While the salinity (180 ppm) and pH (6.97) of the collected clean water was within the World Health Organization drinking water standard.