Journal of the Australian Ceramic Society最新文献

To enhance the piezoelectric performance of the lead-free Bi_0.5Na_0.5TiO₃-BaTiO₃ (BNT-BT) system, we introduced K_0.5Na_0.5NbO₃ (KNN) via synergistic composition modulation. A series of (0.94-x)BNT-0.06BT-xKNN (x = 0.01–0.04) ceramics were synthesized using a solid-state reaction method. The composition with x = 0.02 exhibited optimal performance, achieving a significantly improved piezoelectric coefficient (d₃₃ = 115 pC/N) and a high depolarization temperature (T_d = 138 °C). Comprehensive structural and electrical characterizations revealed that these enhancements originate from KNN-induced modifications, including the coexistence of rhombohedral and tetragonal phases, refined grain morphology, and optimized domain dynamics. This work demonstrates that KNN modification is an effective strategy for tailoring the functional properties of BNT-BT-based ceramics, positioning the optimized composition as a competitive lead-free piezoelectric candidate for advanced electromechanical applications.

Gold nanoparticles (AuNPs) have drawn a lot of interest due to their unique physicochemical characteristics and several biological uses. Glycyrrhiza glabra (licorice root) and Sarpagandha root extract, a well-known medicinal plant with a variety of bioactive chemicals, are used in this study to investigate the green synthesis of AuNPs. The licorice root extract helps to create stable, monodispersed AuNPs by acting as a stabilising and reducing agent. X-ray diffraction (XRD), particle analysis (PA), and UV-visible spectroscopy are used for characterisation. Their potential in vivo angiogenesis and anti-inflammatory study was highlighted by biological evaluations that showed the prospective reduction of capillary. The results indicate that AuNPs derived from licorice and sarpagandha roots have exceptional therapeutic potential and provide a biocompatible and environmentally friendly substitute for biomedical applications.

Hydroxyapatite is a widely explored bio ceramic, but achieving controlled nanorod morphology remains challenging with conventional synthetic routes. This research focuses on synthesizing hydroxyapatite through a novel method using the biopolymers chitosan and cinnamaldehyde for Schiff base template formation. This template guided the mineralization of phosphate and calcium precursors, thus producing well defined hydroxyapatite nanorods with an aspect ratio from 2.5 to 4 as confirmed by SEM analysis. Structural and chemical analysis verified that the synthesized HA is comparable to commercial HA (HA_C). The cytotoxicity of these nanorods using the MTT and live/dead assays on murine fibroblast cells and mesenchymal stem cells showed > 70% viability over 7 days, indicating non toxicity and enhanced proliferation. The osteogenic potential of the hydroxyapatite was confirmed using alkaline phosphatase and ARS staining, where initiation and completion of mineralization was confirmed. Hence, this work introduces a distinctive, template driven approach for synthesizing biologically active HA nanorods, offering a significant improvement over existing commercial hydroxyapatite.

The global rise in bone reconstructive surgeries necessitates effective artificial bone substitutes, with carbonate apatite (CO₃Ap) being a promising candidate for bone regeneration. However, CO₃Ap cannot be sintered due to thermal decomposition at high sintering temperatures. An alternative method to synthesis CO₃Ap is via dissolution-precipitation reaction of precursor such as calcium carbonate (CaCO₃). This study focuses on the feasibility to synthesis CaCO₃ precursor from natural source material such as limestone. In this study, limestone obtained from the Northern Region of Malaysia were utilized to synthesis CaCO₃. The limestone was subjected to calcination, dissolution in distilled water and dried to produce calcium hydroxide (Ca(OH)₂) powder, which was subsequently carbonated at room temperature and 4 °C to produce calcite and vaterite, polymorphs of CaCO₃, respectively. These were then pressed into pellets and immersed in 1 M sodium hydrogen phosphate (Na₂HPO₄) solution at 80 °C for up to 14 days. Characterization using X-ray Diffraction (XRD), Fourier transform infra-red (FTIR), scanning electron microscope (SEM), particle size analyzer and carbon-hydrogen-nitrogen (CHN) analyzer were conducted to examine the formation of CO₃Ap. FTIR analysis identified the synthesized product as AB-type CO₃Ap. Vaterite precursor treated in 1 M Na₂HPO₄ transform to CO₃Ap within 3 days with 13.5 wt% of carbonate content while for calcite precursor, the transformation to CO₃Ap was within 7 days with 11.8 wt% of carbonate content. This is due to vaterite having higher surface area and solubility when compared to calcite in aqueous solution. These findings suggest the feasibility to obtain high-purity CO₃Ap by utilizing locally available limestone are feasible.

A bioactive glass–ceramic with the composition 53SiO₂-20CaO-23Na₂O-4P₂O₅ (wt%) (S53P4) was synthesized using a modified sol–gel route. In this process, Ca(NO₃)₂·4 H₂O, NaNO₃, TEOS, and TEP were hydrolyzed in hot water to form a homogeneous sol, which was subsequently transformed into a gel inside a hydrothermal reactor. The wet gel was then dried by freeze-drying to preserve its porous structure and finally calcined at high temperature to obtain the glass–ceramic material. The synthesized product was characterized by XRD, SEM-EDX, TEM, BET, and ICP-OES analyses. Bioactivity was examined by immersing the powder in simulated body fluid (SBF), while biocompatibility was evaluated using L-929 fibroblast cells. The results show that the obtained glass–ceramic exhibits a nanostructure with an average particle size of 22.86 nm, high porosity, large specific surface area (311.51 m²/g), and significant pore volume (0.791 cm³/g). Upon immersion in SBF, a hydroxyapatite layer formed within 3 days, confirming excellent bioactivity. Cytotoxicity tests demonstrated high biocompatibility, with cell viability exceeding 90% at all extract concentrations and reaching up to 134% at a 25% extract level.

This research reports the synthesis of graphene oxide (GO), reduced graphene oxide (rGO), and composites of zirconium dioxide with rGO (ZrO₂/rGO) using a microwave-assisted, plant-mediated green synthesis approach. Plant extract of Ocimum tenuiflorum (OT) and Azadirachta indica (AI). The synthesized materials were systematically characterized for their morphological, vibrational, optical, structural, and electrochemical characteristics. XRD analysis confirmed structural modifications upon reduction: the interlayer spacing (d) decreased from 0.85 nm in GO to 0.60 nm in AI-derived rGO (NR) and 0.726 nm in OT-derived rGO (TR), while crystallite size (D) reduced from 7.477 nm (GO) to 1.289 nm (NR) and 3.690 nm (TR). For the composites, OT-derived ZrO₂/rGO (T-ZR) exhibited a D of 0.499 nm, which is smaller than AI-derived ZrO₂/rGO (N-ZR. 0.547 nm. Comparative cyclic voltammetry (CV) analysis has demonstrated specific capacitance (C_S) for the N-ZR (756.63 Fg^− 1) compared to N-ZR (251.83 Fg^− 1) and pristine GO (2.95 Fg^− 1) at a scan rate of 5 mVs^− 1.

The treatment of massive bone defects remains a substantial challenge in orthopedic practice due to the limited regenerative capacity of autographs and metal implants. Tissue engineering approaches that integrate Mesenchymal Stem Cell (MSCs), scaffold, dan bioactive metabolites have shown great potential in promoting osteogenesis, particularly through secretome-mediated mechanisms under hypoxic conditions. The objective of this study to examine the effectiveness of metabolites derived from MSCs cultured under normoxic and hypoxic conditions, in combination with hydroxyapatite scaffolds, on bone regeneration in critical-size bone defects at the fourth and eighth weeks. This research is true experimental research which use post-test only control group design. The samples were 42 male New Zealand White rabbits, which were classified into three groups namely, BHA, BHA + normoxic metabolites, and BHA + hypoxic metabolites. These groups were observed at the fourth and eighth weeks. The parameters assessed included microvascularization (MV), woven bone (WB), COL 1, and radiological scores. Data were analyzed using One-Way ANOVA, Brown-Forsythe, Kruskal-Wallis, Mann-Whitney, Post Hoc LSD, and Games-Howell tests to determine significant differences among groups. In addition, statistical analyses were carried out with SPSS, using a significance level of 5% (p < 0.05). The results of the study demonstrated that the implantation of BHA, BHA + normoxic metabolites, and BHA + hypoxic metabolites in the rabbit radius bone produced significant differences in several parameters of bone regeneration. In the 4th week, significant differences were observed in the microvascular and woven bone parameters (p < 0.05), whereas the radiological scores exhibited no significant differences (p > 0.05). At the 8th week, almost all parameters showed significant differences among groups, except for COL 1 (p > 0.05), with notable increases in microvascularization, woven bone formation, and radiological scores compared to the other groups. Normoxic metabolite supplementation with BHA demonstrated superior bone recovery compared to BHA. However, the hypoxic metabolite + BHA composite exhibited the most promising bone regeneration across groups, suggesting its potential as an alternative treatment for critical-sized defects.

This study investigates the gamma-ray shielding performance of alkali-activated materials derived from thermally treated glauconite (TTG) and thermally treated serpentine (TTS), activated by a sodium silicate solution. Three TTS/TTG binders were prepared by substituting TTS with TTG at 0%, 20%, and 40% by weight. The phase composition and microstructure of the synthesized binders (TTS/TTG-0%, TTS/TTG-20%, and TTS/TTG-40%) were characterized using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDX). The gamma-ray shielding parameters mass attenuation coefficient (µ_m), effective atomic number (Z_eff), half value layer (HVL), and exposure build-up factor (EBF) were determined both theoretically and experimentally across a photon energy range of 0.015–15 MeV. Characterization results indicated that adding TTG led to the formation of high-density, iron-rich magnetic phases such as magnesioferrite, and magnetite, alongside hydration products. Both experimental and theoretical evaluations revealed that increasing TTG content significantly enhanced gamma-ray shielding capabilities, attributed to the presence of high atomic number elements within TTG. The measured values aligned closely with theoretical predictions. The study concludes that the incorporation of TTG improves the shielding efficiency of alkali-activated materials due to the formation of dense, magnetic phases. TTS/TTG-20% and TTS/TTG-40% binders demonstrate potential as low-cost, effective geopolymers for radiation shielding applications in nuclear, medical, and industrial fields.

MgO-CaO-Fe₂O₃-x wt.% SiO₂-y wt.% Al₂O₃-z wt.%Y₂O₃ (3≤x≤15, 0≤y≤12, 0≤z≤12) porous ceramics are prepared by the organic foam template method and the mechanical and thermal performance are investigated. The XRD results illustrate that the main phase is MgO, and the secondary phases include MgSiO₃, MgAl₂O₄, and Y₂O₃. The Mg-O-Si and Mg-O-Y peaks are observed in FTIR spectrum, indicating the successful incorporation of additives. The results from mercury intrusion porosimetry show that the porous ceramic is mainly macro-pores, with few meso-pores distributed on the skeleton, which effectively increase total porosity. The SiO₂ doping changes the fracture manner of MgO-CaO-Fe₂O₃ ceramic from intergranular to transcrystalline, co-addition of Al₂O₃ can promote the formation of MgAl₂O₄ spinel that distribute at the grain boundary and decrease grain size of MgO, and the Y₂O₃ could enable uniform grain size distribution, which disperse external forces evenly to improve the mechanical properties. The MgO composite ceramic synthesized by organic foam template method, due to the high total porosity ~85%, exhibits thermal conductivity below 0.07 W/(m·K), which is almost independent of SiO₂-Al₂O₃-Y₂O₃ doping concentration. Typically, the MgO-2.5 wt.% CaO-1 wt.% Fe₂O₃-3 wt.% SiO₂-0.3 wt.% Al₂O₃-6 wt.% Y₂O₃ porous ceramics exhibit total porosity of 84.6%, compressive strength of 4.3 MPa, and thermal conductivity of 0.063 W/(m·K). Benefiting from their outstanding compressive strength and low thermal conductivity, the MgO based porous composite ceramics exhibit significant potential for application as building insulation materials.

This study investigates the stabilization of the metastable β polymorph of dicalcium silicate (belite) through doping with boric acid (H₃BO₃). Belite, a major constituent of Portland cement clinker, exhibits varying degrees of stability under different conditions. The β polymorph is desirable for its hydraulic activity, but it tends to transform to the less reactive γ form upon cooling. Belite (phase-purity > 95%) was synthesized with H₃BO₃ dopant and characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM) techniques and ImageJ-based grain size analysis. The results show that boric acid doping effectively stabilizes the β-belite polymorph at room temperature. In particular, a 0.35 wt% H₃BO₃ addition was sufficient to stabilize the β-belite phase, resulting in 97.71% β-C₂S content. The stabilization mechanism is attributed to the substitution of BO₃ groups for SiO₄ tetrahedra in the crystal structure. Increased sintering time (3.5 h) resulted in higher β-C₂S content and decreased free lime. The synthesis method yields approximately 800 g of β-belite phase (phase-purity > 95%) in a single 7-h run. The results provide valuable insights into the effects of boric acid doping on the stability and hydration behavior of β-belite, which could inform the development of novel cement-based materials with lower energy requirements and CO₂ emissions.