Journal of the Australian Ceramic Society最新文献

Understanding uranium valences in nuclear materials is critical as it is known to influence both their physical and chemical properties. As such, the synthesis of uranium-containing materials with varied uranium oxidation states was achieved and their uranium valences, as determined by diffuse reflectance spectroscopy (DRS), herein reported. It was revealed that DRS was well suited to differentiating between U(IV), U(V) and U(VI) in these materials. The U(IV), visible as broad vibronic absorptions in the UV-vis region, U(V), present as sharp peaks arising from f-f transitions and thus restricted to the near-infrared region and U(VI), featured by broad charge transfer bands in the ultra-violet range, were successfully identified in mono-valent and mixed-valence materials. A particular sensitivity to U(V) was revealed, even when present as a minor species. Of particular note was the capability for DRS to determine the coordination environment about the U(V) centres, with a shift of the diagnostic peak to higher wavelengths when the uranium coordination number was changed from 6-fold to 7- and 8-fold. Highlighted in this work is the potential for DRS to be applied to the analysis of nuclear materials across the entirety of the nuclear fuel cycle, towards better understanding and improving their applications.

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This research presents an efficient and stable photocatalyst for the removal of hospital pollutants, characterized by a rapid reaction rate and a cost-effective, straightforward synthesis process. The study focuses on enhancing the photocatalytic performance of graphitic carbon nitride (g-C₃N₄, abbreviated as g-CN) through selenium (Se), leading to the formation of Se/g-CN nanocomposites. These nanocomposites were synthesized via a sintering method in a tube furnace, with varying selenium concentrations (5%, 10%, and 15% of Se/g-CN ratio). X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy confirmed the formation of a heterostructure between Se and g-CN. Field emission scanning electron microscopy (FESEM) images revealed that selenium incorporation altered the porous morphology of pristine g-CN, transforming it into a flake-like structure in the Se/g-CN nanocomposites. Tetracycline (TC) antibiotic was used as the target pollutant, with the Se(10%)/g-CN nanocomposites achieving 96% degradation under 60 min of commercial, low-power light-emitting diode (LED) irradiation. Additionally, the Se/g-CN heterostructures demonstrated stable photocatalytic activity, maintaining their performance after four cycles of reuse. Band structure calculations indicated that Se/g-CN forms an S-scheme heterostructure, where photogenerated electrons in g-CN act as reducing agents, and photogenerated holes in Se function as oxidizing agents.

In this study, the in vitro mineralization, as well as an antitumor drug (fluorouracil) delivery of sol-gel-derived bioactive glasses doped with a lanthanide (III) element (Yb³⁺), have been investigated. Additionally, the cytotoxicity of the related bioactive glasses was examined against osteosarcoma SaOS-2 and osteoblastic MC3T3-E1 cell lines under in vitro conditions. The results demonstrated that the bioactive glass samples containing rare earth element did not induce cytotoxic effects on the mentioned cell lines for up to 7 days. An increase in alkaline phosphatase enzyme activity was observed for all samples during the incubation period. Drug loading experiments showed that the anticancer drug amount adsorbed onto the bioactive glass powders at pH 7.4 ranged between 25% and 35%. Based on the drug delivery studies conducted in phosphate-buffered saline solution at pH 7.4 and 5.5, cumulative drug release from the bioactive glass powders after 500 h was between 60% and 70% at neutral pH. A higher drug delivery was observed at lower pH value. The drug release kinetics were found to be consistent with the Higuchi model. The findings of this study indicate that bioactive glasses containing trivalent ytterbium possess suitable biological properties for use in biomedical applications and they offer improved biocompatibility providing an ideal environment for bone regeneration.

This study examines the effect of barium titanate addition at 3 different rates (BaTiO₃; 1wt%, 3 wt% and 5 wt%) on the mechanical performance, in vitro bioactivity and morphological structure of beta tricalcium phosphate (β-TCP). The best results for β-TCP were achieved after sintering at 1200^oC and with an average grain size of 5.077 ± 0.571 µ. However, sintering at 1250^oC caused a 45% increase in the grain size of β-TCP, micro cracking and decomposition of 3.2% into alpha tricalcium phosphate (α-TCP) resulting in a decrease in its properties. Depending on the BaTiO₃ ratio, 9 different phases with general chemical compositions of Ba_x/Ca_y-Ti_m-O_n, as well as α-TCP, were detected in the composites. As the sintering temperature and BaTiO₃ ratio increased, the α-TCP ratio in the composites increased to 49.7%. The highest mechanical performances in composites were achieved at the sintering temperature of 1200^oC and with the addition of 3wt%-BaTiO₃. In vitro studies showed that the surface of this composite was completely covered with apatite on the 28th day.

Hydroxyapatite (HAP), a cornerstone of bone and teeth, has ignited interest due to its potential bioactivity and therapeutic implications. This study comprehensively assesses the multifaceted nature of HAP, delving into its antioxidant, thrombogenic, and cytocompatibility properties. HAP was synthesized via the sol-gel method, achieving a Ca/P ratio 1.66, confirmed by energy-dispersive X-ray spectroscopy (EDS). X-ray diffraction (XRD) verified compound formation, while Fourier transform infrared spectroscopy (FTIR) identified functional groups. Field emission electron microscopy revealed the surface morphology of HAP. Its structural characterization delves into HAP’s functional potential. Utilizing the DPPH (2,2-diphenyl-1-picrylhydrazyl) assay, pure HAP’s ability to neutralize free radicals, a symbol of antioxidant activity, was evaluated. Additionally, thrombogenic studies using the whole blood clotting assay explored HAP’s influence on blood clotting, a crucial factor for biocompatibility. The MTT (3-(4, 5-dimethythiazol-2-yl)-2, 5-diphenyl tetrazolium bromide) assay was employed in the L929 cell line to assess its interaction with living cells further, shedding light on HAP’s cytotoxicity or potential cell viability enhancement.

Enhancing the efficacy of energy storage materials is crucial for advancing contemporary electronic devices and energy storage technologies. This research focuses on boosting the energy storage capabilities of BaTiO₃ ceramics through Mg²⁺ doping. Introducing Mg²⁺ ions into the BaTiO₃ lattice induces defects and grain boundary effects, significantly influencing ferroelectric properties. Rietveld refinements of X-ray diffraction confirmed that both pure and Mg-doped samples show the same tetragonal phase. SEM analysis revealed a refined grain microstructure in the Mg²⁺ doped BT sample, which resulted in improved thermal stability and pinched ferroelectric hysteresis loops. Incorporating Mg²⁺ ions into the BT host lattice significantly enhanced energy storage density from 0.204 J/cm³ to 1.42 J/cm³ and efficiency rising from 21 to 89%. This enhancement is attributed to defect dipole engineering and the attainment of fine grain size. Furthermore, an examination of the electronic structure, overall density of states (DOS), and electronic density of both samples is undertaken. The defect dipole mechanism proposed in this study introduces a novel and promising strategy for developing high-performance energy storage in ferroelectric ceramics, holding great promise for next-generation applications.

In this research BaAl₂O₄: Eu²⁺/Li⁺ luminescent materials were synthesized through a facile solid-state approach at 1100 °C. To study the effect of Li⁺ ions, different amounts of LiCl were used within the synthesis of BaAl₂O₄-based compounds. The crystal structural, microstructure, surface characteristics, and photoluminescence properties were scrutinized by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), photoluminescence (PL), Fourier transform infrared (FTIR) analyses. It was shown that the addition of LiCl flux material results in very slight changes in the crystallographic properties of BaAl₂O₄ crystal structure while the use of LiCl has severely reduced the average particle size from about 225 nm to 120 nm. Upon the excitation procedure at the wavelength of 343 nm, BaAl₂O₄: Eu²⁺ shows a strong and wide emission in the range of 435–610 nm that is attributed to the 4f⁶5d¹-4f⁷ transition of Eu²⁺. The highest emission occurs when 2.5 wt% LiCl was utilized as flux material. Moreover, through the employment of XPS characterization, it was proved that the addition of Li⁺ ions causes higher binding energies of elements and improvement of crystallization.