Journal of the Australian Ceramic Society最新文献

Hydroxyapatite (HAp) is observed as a mineral deposition on bones and in teeth enamel and hence serves as an ideal model or as a component for orthopaedic and dental implants. Synthetic HAp has been synthesized on a lab scale for several decades to mimic the naturally occurring HAp based on its chemical and crystallographic nature. There are several methods for synthesis of HAp available in the literature, amongst which the following are a few examples: dry methods which include the solid-state method and mechano-chemical method, wet methods which include chemical precipitation and sol–gel method, and methods which use high-temperature such as combustion method and pyrolysis method. However, more economical and better yield-giving methods produce HAp with controlled morphology for its potential use in biomedical applications. One such method that exploits Schiff base ligands to form chelating complexes with calcium and phosphate precursors and protect generated HAp nuclei is recent ongoing research for the preparation of HAp. This review presents the synthesis of HAp using a wide array of methods, with the recent HAp using novel methods compared to the traditional synthesis of HAp.

The first time machine learning-based refractive index model proposed based on the density parameter using a glass dataset of 2000 oxide glass samples to predict refractive index of the xZnF₂-(20-x)ZnO-40As₂O340TeO₂. The study uses various machine learning techniques such as gradient decent, artificial neural network, and random forest regression to predict the refractive index and density of glasses. The random forest regression (RFR) model is found to be the most effective with a maximum R² value of 0.950 in the case of refractive index prediction and 0.926 for density prediction. The study also investigates the effects of nitrogen ion implantation on the glasses, finding that increased nitrogen dose causes a reduction in density and an increase in refractive index. The glass transition temperature decreases with increased nitrogen dose, possibly due to implantation defects. However, the glass stability increases with increasing implantation dose for low and high fluorine content glasses, likely due to the development of band gap defect levels and an increase in carrier concentration.

An effect of Cu-doped Ni-Zn nanoferrite particles synthesized through the citrate gel auto-combustion method on structural dielectric and magnetic properties was investigated. The structural characterization of synthesized powder is investigated using XRD (X-ray diffraction), FE-SEM (field emission scanning electron microscopy), EDXS (energy-dispersive X-ray spectroscopy), AFM (atomic force microscope), and TEM (transmission electron microscope). All prepared samples were established to have a single-phase spinel structure and fine grain size with an Fd-3 m space group. The lattice parameter, volume, and crystallite size decrease with increasing copper substitution. By adding copper ions, the surface area rises from 123.9 to 187.4 m² g⁻¹. The surface roughness is increased by AFM examination from 7.6 to 11 nm. From the AFM samples, it is shown that they are soft to hard in nature due to the Cu doping. The real imaginary impedance and the complex electric modulus were studied within the frequency range of 20 Hz to 1 kHz at room temperature, respectively. In the Cole–Cole plots studied for dielectric constant, it was observed that all samples had single semi-circles and continuously decreased with increasing copper content. This shows that the prepared material is good for high-resistance applications and the fabrication of multilayer inductor chips. The magnetic characteristics of hysteresis loops were studied at room temperature using a VSM (vibration sample magnetometer) for nanoferrites. The prepared ferrites samples were examined; copper doping increased the width of the loops, which confirms the change from soft to hard magnetic material. They are utilized in data processing, telecommunications, and the automobile industries. At low temperatures, the prepared samples showed superparamagnetic behavior. It is used in medical and electrical device applications.

Owing to the importance of hydrogen metallurgy for the low-carbon and green iron and steel industries, the reduction behavior and microstructure evolution of two iron oxides (hematite and magnetite) at various temperatures were investigated in a pure hydrogen environment (99.999%). The weight loss ratio, total oxygen content, reduction degree, and phase composition of the iron oxides were also discussed. The hematite shows a better reducibility compared to magnetite. It is indicated that hematite and magnetite transform into iron metal with total oxygen contents below 6790 and 25,200 ppm, respectively, when the reduction temperature exceeds 800 °C. Simultaneously, a porous iron skeleton was formed at 800 °C, and the densification of the porous iron occurred with increasing temperature. The impurities in iron oxides significantly affect the microstructure evolution, weight loss ratio, and total oxygen content.

Fabrication of Ti₃SiC₂ from elemental powder compacts was conducted by combustion synthesis in the mode of self-propagating high-temperature synthesis (SHS). Samples were formulated with three atomic ratios of Ti:Si:C = 3:1:2, Ti:Si:C = 3:1.2:2 (with excess Si by 20 mol.%), and Ti:Si:C:Al = 3:1.2:2:0.1 (a Si-rich and Al-added composition). Combustion reaction was highly exothermic and combustion wave velocity (from 4.1 to 8.8 mm/s) and temperature (from 1340 to 1610 °C) increased significantly with sample compact density varied in the range of 45% to 57.5% TMD (theoretical maximum density). In addition to the sample density, excess Si and a small amount of Al contributed greatly to the formation of Ti₃SiC₂. For the powder compacts of 57.5% TMD, the product synthesized from the sample of Ti:Si:C = 3:1:2 was composed of Ti₃SiC₂, TiC, and Ti₅Si₃ at 64 wt.%, 28 wt.%, and 8 wt.%, respectively. The sample with excess Si by 20 mol.% yielded a product with a weight proportion of Ti₃SiC₂:TiC:Ti₅Si₃ = 70:27:3. The product having the highest yield of Ti₃SiC₂ was obtained from the Si-rich/Al-added sample, which produced Ti₃SiC of 83 wt.%, TiC of 13 wt.% and Ti₅Si₃ of 4 wt.%. As-synthesized Ti₃SiC₂ grains were in a thin plate-like shape with 0.5–1.5 µm in thickness and 5–10 µm in length. Ti₃SiC₂ platelets were stacked closely into a layered structure.

Nanomaterials, especially ferrites, have various applications in mechanical, electrical, and optical fields. However, their abilities in environmental applications remain unexplored. In this work, the flash auto-combustion method has been used to prepare three different compositions of CuFe₂O₄, Zn-CuFe₂O₄, and Co-CuFe₂O₄ nanocomposite. The structure, spectroscopic, surface, and morphological properties of the prepared samples were characterized using XRD, FTIR, BET, and HRTEM, respectively. According to XRD analysis, the prepared ferrites consist of nanocrystalline particles with sizes of 24.5, 37.5, and 32.6 for CuFe₂O₄, Zn-CuFe2O4, and Co-CuFe2O4, respectively. Zn-CuFe₂O₄ and Co-CuFe₂O_{4 had a} single cubic phase, while a tetragonal phase was formed in CuFe₂O₄. The addition of cobalt and zinc to copper ferrite increased the crystallite size and the lattice parameters. The absorption band in FTIR spectra, which represents the stretching vibrations along the [MetalO] bond at the octahedral (B) position, was nearly constant (412 Cm⁻¹) by the addition of Zn to CuFe2O4. The surface area and quantity of gas adsorbed on the surface of Co-CuFe2O4 were the highest. The greatest force constants [(Ko = 1.37 & KT = 1.32 105 dyne/cm] were detected in Zn-CuFe₂O₄. Co-CuFe2O₄ exhibited the highest saturation magnetization as well as magnetocrystalline anisotropy. From FESM, the particles have a homogeneous distribution, which is confirmed by the appropriate synthesis method. The nanonanosamples had an average particle size of 79 nm, 66 nm, and 56 nm for CuFe₂O₄, Co-CuFe₂O₄, and Zn-CuFe₂O₄, respectively. The surface area and quantity of gas adsorbed on the sample surface were increased by doping Cu ferrite with Co and Zn. All the prepared samples were tested for heavy metal (Cr⁶⁺) removal from the water; they demonstrated promising results after optimizing the experimental conditions at pH 7 and contact time 50 min, and these values reached 54%, 90%, and 93% for CuFe₂O₄, Zn-CuFe₂O₄, and Co-CuFe₂O₄ nanocomposite, respectively.

This work examines a number of synthetic glasses with the molecular compositions 60B₂O₃, 5CaO, 5Bi₂O₃, and xEr₂O₃ (BBCEr-x, where x = 0.0–2.0 mol%) to determine their structural, optical, mechanical, physical, and γ-rays protective properties. Glass was shown to be in an amorphous state by XRD measurements. The density (ρ) of BBCEr-x grew from 3.14 to 3.32 g/cm³ when the molar addition of Er³⁺ ions increased from 0.0 to 2.0 mol%. The absorbance spectra of the BBCEr-x samples showed seven absorption bands related to the Er3 + electronic transitions (4f–4f). It has been evaluated the dependency of elastic moduli, including Poisson’s ratio (σ), and the efficacy of shielding against incoming gamma rays on [Er₂O₃] mol%. The Makishima-Mackenzie theory was used to calculate the mechanical parameters. As a function of [Er₂O₃] mol%, the micro-hardness (H) of the Vickers increases while the ratio of the Passion decreases. The mass attenuation coefficient (MAC) has been calculated in the energy range of 0.015–15 MeV using the XCOM and Phys-X/PSD programs and has been compared with Monte Carlo simulations performed using the Geant4 code. The linear attenuation coefficient (LAC), transmission factor (TF), and fast neutron removal cross-sections (Σ_R) all showed monotonic dependence on [Er₂O₃] mol%. With photon energies of 0.015–15 MeV, the sample BBCEr-0.0 had the lowest values of MAC, measuring 34.418–0.029 cm²/g. This result reflects the interaction between density and [Er₂O₃] impacts on the mechanical and radiation shielding capabilities of the synthesized glasses. The greatest MAC values were found in the BBCEr-2.0 sample, which ranged from 39.6 to 0.037 cm²/g. It was found that Σ_R approximates the molar volume (V_m) and exhibits the same trending behavior. This study demonstrated that radiation shielding and mechanical properties could both be customized for indoor or outdoor scientific or industrial usage.

The present in vitro study aimed to evaluate the influence of various surface treatments on the micro-shear bond strength (μSBS) of calcium silicate–based materials (CSMs) to resin composite. Two hundred and forty cylindrical acrylic molds were filled with Biodentine, NeoMTA Plus, NeoPUTTY MTA, TheraCal LC, and Well-Root PT. The specimens were divided into four groups: control with no surface treatment, acid-etching, tribochemical silica coating (TSC), sandblasting with aluminum oxide (AL). Resin composite was applied and photo-polymerized. The μSBS was measured and surface alterations were evaluated using a SEM. Data were examined using two-way ANOVA and Tukey tests at a significance level of 5%. The lowest bond strength values were detected in the controls. Moreover, the lowest μSBS was demonstrated in the untreated NeoMTA Plus group, whereas the aluminum oxide–treated TheraCal LC group exhibited the highest bond strength (p < 0.05). Cohesive failures were observed dominantly for Biodentine and TheraCal LC, adhesive failures in Well-Root PT, and mixed failures for NeoPUTTY MTA. Surface treatments increased the μSBS values of CSMs and affected the micromorphology of the sample surfaces. The study suggests that surface treatments would be advantageous on CSMs.

The effect of the secretome addition to the bovine hydroxyapatite (BHA) as a bone graft candidate was observed through some in vitro testing, histopathological anatomy test, and immunohistochemistry test. BHA and secretomes are first synthesized and then immersed in secretomes to gain the BHA-secretome composite scaffold. The scaffold was freeze-dried and underwent some in vitro and in vivo tests such as morphology, functional group, MTT assay, degradation, and swelling tests. The in vivo test was done to know the woven bone, collagen type I, and osteonectin amount formed during the implantation in rabbits for 30 and 60 days. Based on the SEM morphology test, the average pore size in the two groups of samples was 462.15 µm. All scaffolds from this study contain hydroxyapatite’s functional groups matched with literature and are non-toxic after being tested by the MTT assay. These scaffolds could be applied as bone grafts because the percentage of sample degradation is < 30% after 4 weeks and could swell, which would be good for cell adhesion and infiltration during bone healing. The woven bone in the BHA scaffolds and freeze-dried BHA-secretome composite were 371.89 ± 62.09 and 524.69 ± 81.21, respectively. The osteonectin in the composite group was more than in the control group at 30 days in reverse with collagen type 1. The synthesized scaffolds showed good characteristics of bone graft and supported woven bone formation. This composite is suitable for bone graft applications.

In this study, perovskite La_0.8Sr_0.2FeO₃ nanocrystals were formed in heavy metal oxide glass under Al₂O₃ tailoring. The influence of formation of La_0.8Sr_0.2FeO₃ to glass structure and magnetic behavior was studied through various techniques such as X-ray diffraction, Raman, X-ray photoelectron microscopy, electron paramagnetic resonance, and Mössbauer spectra. The 10-30 nm-orthogonal La_0.8Sr_0.2FeO₃ nanocrystals were synthesized and well distributed in glass whose structure and coordination numbers of B₂O₃, Al₂O₃, and Bi₂O₃ were changed by the La_0.8Sr_0.2FeO₃ crystallization. Aluminum abnormality effect was observed in 10%Al₂O₃ doped glass which showed highest transparency, smallest La_0.8Sr_0.2FeO₃ size (10 nm) and least non-bridging oxygen defects. The glass with 10%Al₂O₃ exhibited enhanced electron paramagnetic resonance signal, highest (71%) tetrahedral FeO₄ units and improved Mössbauer sextets intensity which is promising for photonics device applications.