Journal of the Australian Ceramic Society最新文献

The primary scope of this study is to determine the gamma radiation absorption characteristics of a commercial LD glass-ceramic biomaterial through GAMOS simulation and Phy-X/PSD software, and then compare these results with experimental data to provide information about a radiation absorption property of this material. Elemental analyses of the LD glass-ceramic biomaterial were conducted in this research using X-ray diffraction (XRD) techniques. In the experimental study, gamma rays with energies from 81 keV to 1408 keV, emitted by sources such as ¹³³Ba, ¹⁵²Eu, ²²Na, ¹³⁷Cs, ⁵⁷Co, and ⁶⁰Co, were detected utilizing a gamma spectrometer with a 2″×2″ NaI(Tl) detector and associated electronic systems. The experimental radiation absorption data were analyzed alongside the results generated by the GAMOS simulation and the Phy-X/PSD program for comparison. The linear attenuation coefficients were 0.418, 0.361, 0.266, 0.289, 0.250, 0.208, 0.184, 0.175, 0.142, 0.177, 0.123, 0.123, 0.135, and 0.122 cm-1 at gamma energies of 81, 121.8, 276.4, 302.9, 356, 383.9, 511, 661.7, 779, 964.1, 1173.2, 1274.5, 1332.5, and 1408 keV, respectively. The mass attenuation coefficient values began to decrease rapidly as the gamma photon was increased to 1 MeV. Half value layer ranged from 1.315 cm at 81 keV to 6.243 cm at 1408 keV. Similarly, tenth value layer ​​also increased when photon energy increased. The mean free path values ​​vary between 2.394 cm^− 1 and 8.184 cm^− 1. In conclusion, it has been observed that the radiation absorption parameters of lithium disilicate dental biomaterial vary depending on the energy level.

In recent years, heavy concrete has been widely used in industry due to the growing application of nuclear technology and the harmful effects of atomic radiation, such as gamma rays, on the environment. The primary component of concrete is cement, which is the critical factor that determines the most important properties of concrete, such as durability, hardness, and structural integrity. This study suggests that metaschist-modified cement (Portland Cement, CEM I 52.5 N) produced using traditional cement manufacturing methods may offer an alternative to ordinary cement clay-mixed cement (Portland Cement CEM I 52.5 N) for radiation protection in nuclear energy applications. This study comprehensively investigated materials such as ordinary cement clay and metaschist, which can be potentially used to protect radioactive substances in cement mortars. Mortars produced using micronized metaschist (MSC) and ordinary cement clay (OCC) were analyzed at different energy levels. The mass attenuation coefficient (MAC) of cement samples was determined experimentally using various radioactive point sources. Additionally, hydraulic and mechanical tests were conducted based on cement standards (TSE EN 196-1, TS EN 196-3, and TS EN 196-6) to evaluate the performance of the produced cement samples. The results indicate that the metaschist-modified Portland cement (MMPC-52,5/N) mixture demonstrates superior radioactive shielding performance compared to ordinary cement clay-mixed cement (Ordinary Portland Cement, CEM I 52.5 N). Cement samples containing MMPC-52,5/N demonstrate superior performance characteristics and high radiation shielding properties, indicating significant potential for applications in nuclear technology.

The effects of the processing technique on the properties of modified 0.99 Bi_0.5(Na_0.8 K_0.2)_0.5 TiO₃ − 0.01 Bi (Mg_2/3Nb_1/3) O₃ or BNKT-BMN-based ceramics were investigated. The ceramic samples were synthesized by two different techniques, a conventional solid-state technique (CS) and a two-step technique (2-Step). Both techniques yielded pure perovskite phases without any impurity phase. The 2-Step samples presented a finer grain with a higher density than the CS technique. The 2-Step technique also enhanced many electrical properties such as the dielectric constant (ε_r), energy density (W_rec), dielectric breakdown strength (E_b), electro-strain (S), normalized strain (d₃₃*), piezoelectric coefficient (d₃₃), piezoelectric voltage constant (g₃₃), and figure of merit (FoM). Mechanical properties such as hardness (H) and elastic modulus (E) were as well improved by this technique. However, the 2-Step technique promoted a higher heterogeneous conduction, resulting in a higher degree of loss tangent (tanδ)-frequency dispersion, while the observed tanδ values were still low. Therefore, the 2-Step technique positively affects the properties of the studied ceramics and may also positively impact other lead-free Bi-based piezoelectric ceramic systems.

This study, the ceramics’ sintering, mechanical, and dielectric properties were examined, and the influence of HNT additives on these properties was investigated. HNT was added to the structure as a SiO₂ source to the MgO ceramics, which are difficult to process, since SiO₂ suppresses the grain growth of MgO ceramics and significantly reduces the sintering temperature. After calcination at 800 °C HNT at different ratios (1, 3, 5, 7, 9, 11 wt%) were added to calcined MgO powder. As a result of XRD analysis, it was determined that spinel, forsterite and periclase phases were formed and these results were also confirmed by SEM images. The addition of HNT led to the formation of the forsterite phase at grain boundaries, enhancing mechanical properties. The best mechanical properties were observed in MgO ceramics with 11% HNT additives. Adding HNT at different ratios increased the dielectric constant of MgO ceramics. HNT-added MgO ceramics exhibited higher dielectric constant value than those at ambient temperature. The lowest dielectric constant value was measured as ~ 8.5 for MgO ceramic without any HNT addition. Since the materials to be used as circuit substrates require strict dielectric and mechanical properties, it is aimed to improve the mechanical and dielectric properties of MgO ceramics with the addition of HNT. MgO ceramics incorporating HNT in this study exhibited outstanding dielectric and mechanical characteristics, suggesting their potential as favorable materials for circuit substrates.

This work presents the effect of co-doping of strontium (Sr) and copper (Cu) on the properties of nickel oxide (NiO_x) thin films. 3 wt.% of Cu and various compositions (1, 2, and 3 wt.%) of the Sr were successfully co-doped in the NiO_x. Thin films of NiO_x co-doped with Sr and Cu were deposited on a fluorine-doped tin oxide (FTO) conductive substrate using a solution-processed spin coating technique. Their evolution of structural, morphological, and optoelectronics properties were studied by using X-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive x-rays analysis (EDX), ultraviolet–visible spectroscopy (UV–VIS), and Hall effect measurement system. XRD analysis confirmed the crystalline, cubic phase structure and exhibited direction along the (200) plane. SEM demonstrated that all the samples have homogeneous and pinhole-free surfaces. UV–visible spectroscopy demonstrates that with the increase in concentrations of Sr, the transparency of the thin film reduced from 85% to 78%. The band gap of NiO_x reduces from 3.78 eV to 3.73 eV by increasing the concentration of dopant (Sr 1–3 wt.% and Cu 3 wt.%). The most improved band gap of 3.73 eV was achieved with a co-doping of 3 wt.% Sr and 3 wt. % Cu in NiO_x. The Electrical conductivity of NiO_x was improved by adding the dopant due to the replacement of Ni ions by Sr and Cu. The optimum conductivity (5.67 × 10^–5 (1/ Ω-cm)) was achieved at Sr (2 wt.%) and Cu (3 wt.%). As a result of improved electrical conductivity Sr, and Cu co-doped NiO_x thin films can be used in different types of optoelectronic and photovoltaic applications, such as organic light-emitting diode (OLEDs), gas sensors, electrochromic devices, and solar cells.

The effect of BaO/CeO₂ substitution on the structure, linear optical properties, and γ-ray absorption efficiency of glasses with formulation 50B₂O₃ + 25Bi₂O₃+(10-x)BaO + 15Li₂O + XCeO₂: X = 0 (BBBLC-0.0) – 1 (BBBLC-1.0) mol% has been investigated. The traditional melt-quenching route is used for the glass production process. Raman spectroscopy, UV-Vis measurement, MCNP simulation code and EpiXs software were employed to achieve the mentioned objective. Density (ρ) slightly increased from 4.6892 to 4.7011 g/cm³, while molar volume (V_m) decreased from 36.4913 to 36.4389 cm³/mol as CeO₂ increased in the glass network. Raman intensity decreased as the concentration of CeO₂ increased in the glass network, which leads to a decrease in the formation of additional non-bridging oxygen (NBO) and bond breakage. The values of direct optical gap ((:{varvec{E}}_{varvec{g}}^{varvec{D}varvec{i}varvec{r}varvec{e}varvec{c}varvec{t}})) reduced going from 2.53 ± 0.01 eV to 2.25 ± 0.01 eV, while values of the indirect gap ((:{varvec{E}}_{varvec{g}}^{varvec{I}varvec{n}varvec{d}varvec{i}varvec{r}varvec{e}varvec{c}varvec{t}})) varied from 2.51 ± 0.01 eV to 2.17 ± 0.01 eV. Values of Urbach’s energy (E_U) declined from 0.4052 to 0.3282 eV for BBBLC-1.0. As the substitution ratio of Ce ions increased, the refractive index (n) and optical dielectric constants (ε₁ and ε₂) improved. Linear absorption coefficient (:left({upmu:}right)) verified as: BBBLC-0.0 < BBBLC-0.25 < BBBLC-0.5 < BBBLC-0.75 < BBBLC-1.0. In terms of half-value (HVl), and tenth-value (TVl) values, the synthesized BBBLC-1.0 sample is the lowest. When compared to the manufactured BBBLC-X glasses, the BBBLC-1.0 sample offers superior protection against gamma radiation.

This study explores the impact of bismuth (Bi) and erbium (Er) co-doping on the structural, morphological, and electronic properties of hydroxyapatites (HAp). Bi/Er co-doped HAp samples at varying concentrations were synthesized through a wet chemical process and characterized using X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, and scanning electron microscopy (SEM). Additionally, density functional theory (DFT) was employed to analyze band structure (BS), energy gap (Eg), density of states (DOS), and linear attenuation coefficient (LAC). Results revealed a systematic decrease in the energy gap from 4.0340 eV to 3.9222 eV with increasing Bi content, highlighting a reduced band gap energy trend as the Bi and Er concentrations increase. Higher Bi concentration also influenced the DOS and BS, and reduced crystallite size (D) across samples. Among them, the 0.26Bi-0.39Er-HAp sample exhibited the lowest crystallinity (76.56%) and smallest crystallite size (27.84 nm). This study provides valuable insights into how co-doping affects HAp properties, with potential implications for biomedical and environmental applications.

Hydroxyapatite (HAP) has a composition that is analogous to that of real bone. Because of this, titanium alloys coated with HAP material have been a widespread choice for bone implants in load-bearing applications. Due to the HAP coatings’ restricted osteo-inductive capabilities, growth factors or dopants can be added for better osseointegration. The purpose of this work is to examine the impact of naturally occurring Centella Asiatica extract (CAE), on the viability of osteoblast like MG-63 cells in-vitro along with the Fe and Ce doped hydroxyapatite (MHAP)/Bovine serum albumin (BSA) composite coatings. The MHAP ceramic was prepared by wet precipitation method. The MHAP/BSA/CAE composite coatings were developed on the titanium (Ti) surface with the use of dip coating method. The coatings were characterized by FT-IR, XRD, SEM, and TEM techniques. SEM with EDX and HR-TEM techniques provided the morphological data and bio-activity nature of the prepared coatings from micro to nano scale levels. The in-vitro results indicate that the addition of CAE has increased the osteoblast cell viability along with increased anti-bacterial activities against gram-negative E. coli and gram-positive Staphylococcus strains. Meanwhile MHAP/BSA/CAE coatings at high concentrations was toxic to osteoblasts cell viability. But it clearly inhibited the bacterial growth. Our findings show that using natural extract in conjunction with a naturally obtainable bio protein on a titanium implant covered with doped hydroxyapatite can effectively regenerate bone tissue along with anti-microbial ability for orthopedic applications including weight bearing conditions.

Magnesium aluminate has the spinel structure and, due to good mechanical, chemical, and thermal properties, has a wide range of applications including refractory ceramics, optically transparent ceramic windows, and armors. Calcined MgO and Al₂O₃ powders were mixed in a one-to-one molar ratio to produce phase-pure spinel. The MgO powder was calcined at 1000 ^oC for 1 h prior to mechanical activation to avoid presence of hydroxide and carbonate at the powder surface. The powders were mechanically activated for 15, 30, and 60 min in a high-energy planetary ball mill in air atmosphere. The mechanically activated powders were pressed into pellets and heated to 1300 ^oC at 10 ^oC/min and held for 1 h for the reaction. Afterwards pellets were ground and sieved. Synthesized powders were sintered at 1450 ^oC at 10 ^oC/min for 2 h and examined for phase composition, crystal structure, and morphology. The results showed that mechanical activation and sintering led to formation of pure spinel phase. Mechanical activation times of 30 min and 60 min led to spinel that was more highly crystalline and phase-pure. Raman spectroscopy showed the presence of all five Raman active modes (A_1g + E_g +3T_2g), and their positions were in a good agreement with previous investigations. Powder morphology analysis showed that particles were comminuted, but that agglomerates formed for longer activation times. The maximum in the particle size distribution curves decreased from 14.7 μm for non-activated powder to 9.1 μm after 15 min of mechanical activation and 8.1 μm after 30 min of mechanical activation, but increased to10.5 μm after 60 min of activation.

Laser processing the surfaces of plasma-sprayed thermal barrier coatings is one of the methods used to improve the corrosion resistance of the coatings. However, laser glazing alone is not sufficient to fully protect coatings from corrosion. In this study, optimum laser surface modification parameters were determined for plasma-sprayed LZ/YSZ double-layer thermal barrier coatings. The coating surface, whose entire surface was scanned with optimum parameters, was modified with nano YSZ using the electrophoretic deposition technique. Thus, the network cracks formed during laser glazing were filled with nano YSZ. The coating modified by laser and electrophoretic deposition processes was subjected to corrosion tests. As a result of the characterizations, it was determined that the optimum laser surface modification parameters for LZ/YSZ thermal barrier coatings were 200 mm laser distance, 120 scan speed, and 28w laser power. With these parameters, discontinuities on the as-sprayed coating surface were eliminated. A dense layer was successfully created on the LZ layer. As a result of the corrosion tests, it was determined that modifying the laser-glazed surface with nano YSZ reduced the penetration depth of corrosive contaminants. Thus, the glassy melt and hot corrosion resistance of LZ/YSZ thermal barrier coatings was increased.