Journal of the Australian Ceramic Society最新文献

While sustainable material systems have become paramount, recycling unused waste cathode ray tubes (CRTs) glass can possess great potential for radiation protection applications. With this motivation, the present study addressed the utilization of waste CRTs in combination with MoO3 towards a glass composition of xMoO₃—(100-x)CRTs where x typifies 0, 1, 3, and 5 wt%. The glass samples coded Mo0 to Mo5 were synthesized using a traditional melting technique. After successfully preparing the glass series, some sets of characterization analyses were performed to understand physical, structural, optical, and radiation shielding properties. According to the findings, density increased from 2.92 to 2.96 g/cm³ as MoO₃ was introduced into the glass network. Yet more, all glass samples exhibited an amorphous structure irrespective of varying MoO₃ doping rates. On the other hand, FTIR measurements paved the way for highlighting possible vibrational modes, such as Si–O-Si and Si–O, in the structure. According to the optical properties via UV–Vis, the direct E_g values equaled 1.75, 1.69, 1.65, and 1.61 eV for Mo0 to Mo5, respectively, whereas R values ranged from 2.8534 to 2.9281. For investigating mass attenuation coefficients (MAC), the transmission measurements were performed for 30.9–383 keV photon energy ranges using radioactive source of 133-Ba and Ultra-Ge detector. The correctness of the experimental MAC values were checked with EpiXS program and MCNP codes. It is determined that the highest MAC values changing from 0.5951 cm²/g to 0.1022 cm²/g belong to Mo5 glass for 30.9–383 keV. It is also revealed that with the increasing MoO₃ addition, EABF, EBF, HVL and MFP values of the Mo0-Mo5 glasses dropped and MAC, Z_eff and N_el values enhanced. As a result, MoO₃ substitution has improved the material characteristics of CRTs glasses.

As the world becomes increasingly aware of the devastating effects of climate change, the need for sustainable building materials that are both durable and environmentally friendly increases. Geopolymer and alkali-activated materials formed by a chemical reaction between an alkaline activator solution and an aluminosilicate source have gained popularity in recent years. The alkaline activator solution dissolves the aluminosilicate source, which then undergoes a polycondensation reaction to form a three-dimensional geopolymeric gel network. The development of this network ensures the strength and durability of the material. Today, this phenomenon of durability has been studied in detail to enable the development of superior construction materials, taking into account degradation mechanisms such as carbonation, leaching, shrinkage, fire, freezing and thawing, and exposure to aggressive environments (chlorides, acids, and sulphates). Although there are many unsolved problems in their engineering applications, slag-based alkali-activated materials appear to be more advantageous and are promising as alternative materials to ordinary Portland cement. First of all, it should not be ignored that the cure sensitivity is high in these systems due to compressive strength losses of up to 69%. Loss of strength of alkali-activated materials is considered an important indicator of degradation. In binary precursors, the presence of fly ash in slag can result in an improvement of over 10% in compressive strength of the binary-based alkali-activated materials after undergoing carbonation. The binary systems can provide superior resistance to many degradation mechanisms, especially exposure to high-temperature. The partial presence of class F fly ash in the slag-based precursor can overcome the poor ability of alkali-activated materials to withstand high temperatures. Due to the desired pore structure, alkali-activated materials may not be damaged even after 300 freeze–thaw cycles. Their superior permeability compared to cementitious counterparts can extend service life against chloride corrosion by more than 20 times. While traditional (ordinary Portland cement-based) concrete remains the most widely used material in construction, geopolymer concrete’s superior performance makes it an increasingly emerging option for sustainable and long-lasting infrastructure.

In this article, the dielectric properties of a Li₄Ti₅O₁₂ (LTO) ceramic at the radio frequency (RF) and microwave (MW) regions were evaluated. X-ray diffraction showed that LTO was obtained without the presence of spurious and/or secondary phases. Complex impedance spectroscopy (CIS) analysis was conducted, whereas an activation energy (E_a) of 0.88 eV was observed. The temperature capacitance coefficient (TCC) was also calculated and demonstrated that LTO could be employed as a Class 1 ceramic capacitor. In the MW region, LTO presented ε’_r = 25.4, tan δ = 5.7 × 10^–4, and τ_f = -14.5 ppmºC⁻¹, values that are interesting for devices that operate in the MW region. Numerical simulation demonstrated values of a realized gain of 4.78 dBi, a bandwidth of 227 MHz, and a radiation efficiency of 98%. Moreover, LTO was evaluated as a temperature sensor operating in the MW region and demonstrated a sensitivity of -0.06 MHz ºC⁻¹. The values presented demonstrate that LTO could be employed in devices that operate in RF and MW regions.

With the acceleration of industrialization, environmental issues have received great attention from governments and societies around the world. Utilizing solid wastes containing valuable heavy metals and exploring their role and application in materials is one of the focal issues of environmental protection in recent years. In this paper, in order to explore the effect of Mn content on the crystallization of CaO-MgO-Al₂O₃-SiO₂ glass–ceramics, glass–ceramics with different content of MnO₂ were prepared by sintering method and the effect of MnO₂ doping on the crystalline properties, glass stability and heavy metal fixation properties of the stainless steel slag glass–ceramics was investigated by differential scanning calorimetry (DSC), Raman spectroscopy, X-ray diffraction (XRD) and scanning electron microscope (SEM). The analysis using crystallization kinetics showed that surface crystallization dominated the whole crystallization process in the range of 0% to 10% MnO₂ content. The peak glass crystallization and depolymerisation temperatures of the glass–ceramics increased gradually with increasing MnO₂ content, and the main crystallization mode of the samples was one-dimensional crystallization. The main crystalline phase of the resulting glass–ceramics was transformed from diopside to spinel, with a crystallization temperature of 860℃. Heavy metals solidified in the spinel phase. This study shows that heavy metals can be effectively immobilized in glass–ceramics. In summary, the use of solid waste to prepare final products with good environmental performance provides a feasible way to utilize solid waste resources.

Face–centered cubic–Bi₂O₃ (δ–phase) material is a better ion conductor when compared to other types of solid electrolytes that have been declared in the literature due to its anion–defective crystal configuration, and hence it can be a promising solid electrolyte choice for intermediate temperature SOFC applications. In this research, Er–Ho–Tb co–doped Bi₂O₃ compounds were successfully synthesized by the solid–state reaction method and characterized using the XRD, TG & DTA, FPPT, and FE–SEM techniques. Apart from sample 4Er4Ho4Tb, each sample became stable with a cubic δ–phase at room temperature, according to XRD patterns. The DTA curves revealed no exothermic or endothermic peaks, implying a phase change in the constant heating cycle. The conductivity of Ho–rich compositions was higher than that of others, confirming the impact of cation polarizability on conductivity. In addition, at 700 °C, the sample 4Er8Ho4Tb with 1:2:1 content ratios had the highest conductivity of 0.29 S/cm. The porosity on the grain boundaries increased with doping, leading to higher grain boundary resistance, which could be responsible for the conductivity drop.

In the present study, for the first time the machine learning (ML) based refractive index (n) approach is established depends on the density (ρ) parameter of glasses for a dataset of 2000 oxide glasses to predict refractive index of B₂O₃-CaO-Li₂O-Sb₂O₃ glasses. Density of the investigated glasses varied from 2.56 to 2.97 gm/cm³. The corresponding refractive index was changed from 2.540 to 2.405. The refractive index prediction based on density parameter derived from the density of glasses and constant ‘K’. For all M-L techniques including gradient descent (GD), artificial neural network (ANN), and random forest regression (RFR), the density factor is used as an independent variable and the experimental refractive index as a dependent variable. The data set of 10,000 oxide glass samples was employed to forecast density using a variety of machine learning approaches. In comparison to other models, the Random forest regression (RFR) model fitted the glass data with the highest R² value of 0.949 for refractive index prediction and 0.925 for density prediction. For both the prediction of density and refractive index, the R² is controlled to 0.932 and 0.9223, respectively. The highest R² values for refractive index and density prediction were gained when the tanh activation function was used in an artificial neural network (ANN) with varied activation functions.

The need for biomass materials that are both cost-effective and highly effective has increased rapidly in a number of areas, including flexible electronics. The aim of this research is to investigate the properties of a screen-printed thick film of Prosopis Africana charcoal (PAC) on an alumina substrate. The biochar was obtained from the Prosopis Africana strain by subjecting it to controlled pyrolysis at 500 °C for 3 h. The rheological properties of the PAC pastes were formulated at a powder-to-organic binder ratio of 40:60 wt%. An average 11.8-µm-thick layer was produced using the screen-printing process. X-ray diffraction analysis showed the presence of characteristic peaks at approximately 25.0° and 44.7°. These peaks correspond to the (002) and (004) reflections of the graphite structure. Thermogravimetric analysis revealed that the PAC film exhibited thermal stability in an airflow environment up to 650 °C. The surface morphology of the PAC thick film exhibits a reticulated appearance with patchy features, while elemental composition analysis (EDX) confirmed the high carbon content of the PAC thick film. The real and imaginary dielectric constants of the PAC thick film at 10 GHz were found to be 9.8 and 1.8, respectively. It can be concluded that the PAC biochar has promising electronic properties, making it a suitable candidate as an environmentally friendly material for a range of electronic applications.

Hydroxyapatite (HA)-based nanocomposite coatings on 316L stainless steel (SS316L) implants can be modified by components such as chitosan/gelatine (CS/Gel) and reduced and functionalized graphene oxide (rfGO) to improve antibacterial properties and biocompatibility. In this research, HA and rfGO were produced. HA-CS/Gel-rfGO nanocomposites with different HA values (200, 500, 800, and 1100 mg) were applied by electrophoretic deposition (EPD) at various voltages (80, 100, and 120 V). Analyzing HA and rfGO by XRD, SEM, and FTIR proved the successful synthesis. The contribution of HA and coating voltage was investigated on the morphology, microstructure, and corrosion behavior by morphological studies, electrochemical impedance spectroscopy (EIS), and potentiodynamic polarization. The possible intermolecular interactions between coating components were evaluated and found to be effective on the coating performance. Increasing HA reduced the cracks but caused unfavorable agglomerations and uneven distribution of the constituents in the coatings. Higher voltages caused voids and porosities. The coating at 1100-mg HA was porous but crack-free. The coating thickness increased by voltage and HA, from ~ 9.3 to 14.8 µm. Electrochemical polarization and EIS analysis in SBF solution showed that corrosion behavior is affected by coating morphology and bonding configurations among HA-CS/Gel-rfGO. The lowest corrosion rate occurred in the lowest HA (200 mg), with a corrosion resistance of 143,000 Ω.cm². At constant HA, increasing the applied voltage significantly decreased the corrosion resistance from 23,046 to 15,000 Ω.cm², and an induction bend occurred at 120 V. The corrosion mechanism was carefully investigated by an equivalent circuit with two time constants and corresponding dielectric capacitors.

This study focuses on how titanium oxide (TiO₂) in concentrations ranging from 0.5 to 4% by weight added the hydroxyapatite (CHA) made from chicken femur bones’, affects sinterability, microstructural, mechanical, and in vitro bioactivity properties. According to the results of the experiments, it was determined that CHA decomposed into whitlockite, alpha tricalcium phosphate (α-TCP), tetracalcium phosphate (TTCP), and calcium oxide (CaO) phases at different temperatures. Rutile and perovskite (CaTiO₃) phases were also found in TiO₂ added CHAs in addition to these phases. With increasing sintering temperature of CHA, the diameters and the heights of the samples decreased. Density increased up to 1250 °C and decreased at 1300 °C respectively. while the partial density value showed similar behavior with density and hardness, At 1200 °C, the maximum values of fracture toughness (1.071 MPam^1/2) and compressive strength (145.417 MPa) were attained; however, as sintering temperatures increased, these values shifted downward to 0.882 MPam^1/2 and 111.096 MPa, respectively. It has been determined that grain growth and decomposition are the underlying factors in obtaining the highest density, hardness, fracture toughness and compressive strength values for CHA at different temperatures. Among the TiO₂ added CHAs, the best properties are obtained for CHA-0.5TiO₂ sintered at 1300 °C (Density: 3.0057 g/cm3, Hardness: 3.973 GPa, Fracture toughness: 1.583 MPam^1/2 and Compressive strength: 170.045 MPa) and the properties of the CHA-TiO₂ composite decreased with increasing TiO₂ ratio. This is due to the fact that increasing TiO₂ has a detrimental impact on CHA’s sinterability behavior and causes it to become more porous and degrade more quickly. It was discovered through in vitro bioactivity and cell culture assays that the addition of TiO₂ had a detrimental impact on the proliferation of bone tissues.