Journal of the Australian Ceramic Society最新文献

Charged particles have been extensively utilized in medical physics as well as in numerous radiation investigations, including cosmic radiation, which is formed of nearly 99% alpha and protons. In this study, lithium-borotellurite glasses strengthened through cerium (IV) oxide (TBLC groups) and gadolinium (III) oxide (TBLG group) are examined on mass stopping power, projected range, and KERMA parameters over the kinetic energy range from 0 to 10 MesV. SRIM and PAGEX code are utilized for determining the critical parameters. The TBLG20 sample with the greatest material density as well as Gd reinforcement is reported with the highest KERMA value. TBLG20 sample consistently yields the lowest values for the mass stopping power values obtained for alpha and protons. Moreover, alpha and proton mass stopping power values are reported to be the lowest for the TBLG20 sample. The lowest projected range values are observed for the TBLG20 sample with the greatest amount of Gd addition. This noticeable difference confirms the superiority observed in KERMA and mass stopping power values and is attributed to the maximal Gd contribution. It can be concluded that Gd reinforcement into tellurite glasses may provide a non-decreasing monotonic effect on stopping power properties of high-density tellurite glasses.

Effects on mechanical and γ-ray shielding competence of TiO₂-based glasses of chemical composition: 30PbO⋅4MoO₃⋅(66 − z)B₂O₃⋅zTiO₂ (0.0 < z < 2.0 mol%) was calculated in this report. The glass density was found to increase in the range of 4.650–4.696 g/cm³ concurrent with a decline in the oxygen molar volume (OMV) from 10.633 to10.547 cm³/mol when [Ti⁴⁺] molar fraction is increased in the glass samples. The Gibbs free energy was found to be between 20.874 and 22.586 kJ/cm³ and was found to be influenced by TiO₂ concentration in these glasses and on the valance states of Ti³⁺ and Mo⁵⁺. The affinity of mass attenuation coefficient (MAC) values (0.039 < MAC < 6.198 g/cm³) in the examined photon energy domain 0.015 < E < 15.0 MeV has the following chronological sorting: MAC_T0 < MAC_T2 < MAC_T4 < MAC_T6 < MAC_T8 < MAC_T10 < MAC_T15 < MAC_T20. The half-value-layer (HVL) trend of Mo-glasses was balanced against two standard RS-glass systems and discovered to possess a less γ-ray shielding competence as RS-(360, 520) or concrete. Also, we found that when the [Ti³⁺]/[Mo⁵⁺] ratio exceeds 0.8 mol%, then both ions participate in the studied properties via de-polymerization of the glass network. These outcomes revealed that the safety effectiveness against radiation and physic-mechano-properties can be synchronized for diverse purposes.

In this paper, the simulated nuclear waste was successfully immobilized by using aluminosilicate glass made from natural granite material without other additive agents. The neodymium-doped matrix’s phase composition, microstructure, element distribution, hardness, density, indentation fracture toughness, and aqueous durability were analyzed. The results show that the samples with a neodymium content of 10 wt.% are fully vitrified and reach the maximum neodymium solubility. The silicate tetrahedra of glass networks mainly exist in sheets (Q³) and frame (Q⁴) units. Neodymium oxide acts as a glass modifier and destroys the sheet form and may precipitate metal elements in the matrix, resulting in a Vickers hardness of up to 8.17 GPa for this aluminosilicate glass. However, the indentation fracture toughness decreases. Moreover, NR_Nd is about 10⁻⁷ ~ 10⁻⁸ g·m⁻²·d⁻¹ during the 28-day aqueous durability test, indicating its excellent aqueous durability. This work provides a new idea for immobilizing radionuclides via glass.

In this research, the microstructural and mechanical characteristics of metakaolin-based geopolymer reinforced with chamotte particles was investigated at room temperature and after exposure to high temperatures (600–1200 °C). The flexural strength and the appearance of the samples indicated the effective presence of chamotte particles as a reinforcement within the matrix of geopolymer. This was due to crack control in the composite and enhanced volume stability. The connection between chamotte particles and geopolymer binder boosted the flexural strength to 22.15 ± 1.37 MPa at room temperature. Heated composite samples at 800 °C showed improved mechanical performance of the thermally stable chamotte aggregates. However, leucite crystallization at 1000 °C caused volume instability and upon elevating temperature to 1200 °C, leucite peak intensity was more pronounced, which was responsible for the reduction of the strength in the composite. As a result, leucite phase formation in the matrix changed the connection behavior to the fragile state and the particles departed the matrix at high temperatures. The results of this research revealed good compatibility between the geopolymer matrix and chamotte particles for producing low-cost castable refractories up to 800 °C.

In the present study, gamma-ray attenuation properties as well as transmission factor values of high-density sodium metaphosphate-tungsten trioxide glasses with chemical composition of (40−x)NaPO₃−xWO₃-60Sb₂O₃: (x = 0 (S1), 5 (S2), 10 (S3), 15 (S4), 20 (S5), 30 (S6), and 40 (S7) mol%) have been investigated. MCNPX general purpose Monte Carlo code and Phy-X/PSD program were utilized for the calculation of transmission factor values and fundamental gamma-ray shielding parameters. Our findings suggest that the S7 sample (with the highest WO₃ content mole%) has possessed the maximum mass attenuation coefficients (μ_m) at all gamma-ray energies investigated. In terms of half value layer (HVL) and mean free path (MFP), the coded glass sample S7 has achieved the minimum values. The effective atomic number (Z_eff) and equivalent atomic number (Z_eq) of the investigated glasses have the same trend of mass attenuation coefficient. The raising of WO₃ content in mole% in glasses leads to reducing both exposure and absorption buildup factor values for all mean free path values. The minimum transmission factor (maximum attenuation) quantities were verified at a thickness of 3 cm for all investigated glasses. It can be concluded that the S7 sample exhibits superior radiation shielding characteristics.

In this study, meta-halloysite (MH) mixed with an alkaline solution (8, 10, and 12 M) was used as a binder phase to produce geopolymer mortars with alkaline solution/MH ratios of 0.6, 0.7, and 0.8. The flow slump behaviour, setting time, and mechanical properties of the end products were studied at room temperature. The microstructural properties of the geopolymer mortars were evaluated using scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy. The matching slump values of fresh geopolymer mortars dropped as the alkaline solution concentration increased. The initial setting time increased as the alkaline solution/MH ratio grew (from 0.6 to 0.8). Increasing the alkaline content above 0.6 was averse to the development of strength and densification of the structure. The geopolymer mortar sample made with 0.6 and 12 M NaOH had a high compressive strength (65 MPa), low porosity, and low water absorption. According to the current study findings, geopolymer mortar has demonstrated great practicality and application potential for usage as an environmentally friendly building material, which may be a viable alternative for typical cement mortar in the future.

In this work, some transparent aluminum sodium borate-based glasses containing Dy₂O₃ have been prepared using the melt quenching method. The incorporation of Dy³⁺ ions in the glass network leads to increase and decrease the density and molar volume, respectively. The structural properties are investigated by XRD and FTIR spectroscopy. It is revealed that addition of Dy₂O₃ causes a conversion of boron coordination from BO₄ to BO₃, which indicates the increase in the number of non-bridging oxygen. Therefore, the optical band gap is found to decrease as the Dy³⁺ ions content increases. The temperature dependences of dielectric constant and AC conductivity are studied at different frequencies. The electric conductivity and dielectric parameters decrease with increasing Dy³⁺ content due to the decrease in Na⁺ ions mobility due to the blocking effect of Dy³⁺ cations in the glass network. The shielding factors have been evaluated for the prepared glasses with the help of Phy-X program. The maximum linear attenuation coefficient (LAC) is found at 0.284 MeV and varied between 0.125 and 0.140 cm⁻¹. The results revealed that the incorporation of Dy₂O₃ into the glasses has a substantial effect on the Z_eff.. The value of the Z_eff for the D1 sample, which does not include any Dy₂O₃, stays relatively the same, ranging around 7.51. We found that the rate of reduction in Z_eff was significantly high when the energy of the photons is smaller than 0.826 MeV. From the Z_eff data, we found that the addition of Dy₂O₃ to the glasses improves both their capacity to absorb and their capability to scatter ionizing radiation.

Common high-temperature thermoelectric materials' expensive and rare element contents create a need to develop readily available and cost-effective materials such as carbides, as they have naturally abundant constituents, low costs, and good high-temperature performance. Although there are published research results on the thermoelectric properties of B₄C and SiC, they vary widely in production and characterization methods, hence the results. To efficiently compare these materials and initiate a starting point for material selection for developing thermoelectric ceramics and composites as alternatives to toxic and costly common high-temperature thermoelectric materials, B₄C, SiC, and TiC were spark plasma sintered under similar conditions with different sintering temperatures due to the different characteristics of the materials. Their thermoelectric properties were analyzed between 323 and 923 K and compared. Thermoelectric properties of TiC were investigated in detail for the first time. The results demonstrated that SiC has a high Seebeck coefficient (564.4 µV/K), low electrical (602.1 S/m), and high thermal conductivity (65.8 W/mK), B₄C has high electrical (6974.8 S/m) and low thermal conductivity (12.4 W/mK), and relatively high Seebeck coefficient (269.5 µV/K). In contrast, TiC has metallic electrical (1.3 × 10⁶ S/m) and relatively low thermal conductivities (32.8 W/mK) while a very low Seebeck coefficient (-9.9 µV/K).

Synthesis of Ag-coated BiVO₄ nano/heterostructured photocatalysts was carried out through a two-step process, and their performance was comprehensively evaluated, in this study. The as-synthesized photocatalysts were characterized by X-ray diffraction (XRD), Fourier transfer infrared spectroscopy (FT-IR), Raman spectroscopy, transmission electron microscopy (TEM), field-emission scanning electron microscopy (FESEM), energy-dispersive spectroscopy (EDS), and UV–Vis diffuse reflectance spectroscopy (UV–Vis DRS). Ag nanoparticles were successfully coated on walnut-like BiVO₄ microarchitectures assembled from sphere-shaped nanostructures. Based on the optical results, Ag coating could effectively promote visible light absorption and greatly increase the light absorption threshold because of the synergistic effect on the surface plasmon resonance (SPR). Evaluations of nano/heterostructures’ photo-reactivity were conducted by photodegradation of methylene blue (MB) in an aqueous environment subject to visible light irradiation (VLI). All Ag-BiVO₄ nano/heterostructured samples showed improved photocatalytic efficiencies compared to Pure-BiVO₄ sample, as approved by optical absorption studies. The Schottky scheme mechanism, which introduced a charge transfer route at the metal–semiconductor interface, was also discussed for photocatalytic reactions.