Journal of the Australian Ceramic Society最新文献

Due to the rapid development of China’s regeneration industry, secondary aluminium ash (SAA) has been extensively produced. The reuse of SAA and Y₂O₃ doping was studied in this research. This proved that SAA can turn into a raw material for gehlenite/magnesia-alumina spinels. Furthermore, doping with Y₂O₃ can aggrandize the densification feature of gehlenite/magnesia-alumina spinels. The densification of the gehlenite/magnesia-alumina spinel without Y₂O₃ was lower than that of the doped spinel in the temperature range of 1573 to 1773 K. At 1673 K, 3 wt% Y₂O₃ was added to the gehlenite/magnesia-alumina spinel. It had a density of 2.05 g·cm⁻³ and a compressive strength of 91.2 MPa. Generally, 3 wt% Y₂O₃ was added, and the sintering temperature at 1673 K was appropriate. The elevation of the densification feature was also attributable to the solubility of Y₂O₃ and the formation of a low-viscosity liquid phase such as YCaAl₃O₇. The SAA can be reused for the recovery of gehlenite/magnesia-alumina spinels. Doping it with Y₂O₃ can broaden its reutilization in new water-resistant ceramic materials.

The electrolyte additives are used in dye-sensitized solar cells to improve the photovoltaic performance of the devices, but they still remain their problems on the long-term stability of the solar cells and chemical safety. We have studied the use of two deep eutectic compounds based on choline chloride and phenol with two ratios of 1:2 and 1:3 as alternative electrolyte additives. These compounds own their advantages as eco-friendly chemicals, low cost, and simple synthesis process even at a large amount production. The two compounds, in comparison with the popular additive 4-tert-butylpyridine (4-TBP), were implemented in the functional devices which were characterized by current–voltage measurement and electrochemical impedance spectroscopy. Results showed that the two new additives could improve open circuit voltage values about 10–40 mV, whereas about 100 mV for 4-TBP, compared to the case without additives. Furthermore, using these new additives could result in a higher the short circuit current (J_sc) which was not observed with 4-TBP. These phenomena were explained by the shielding effects and charge transfer processes at the interfaces of electrodes and electrolyte. This study helped to design new efficient and eco-friendly additives for dye-sensitized solar cells in future scale-up production and commercialization.

To promote sustainable development in the refractory industry, ferrotitanium slags, including titanium–alumina slag (TAS) and calcium alumino–titanate (CAT), were used in this study to prepare Al₂O₃-SiC-C (ASC) castables. In this study, low-cost ASC castables were prepared using TAS and compared with those prepared using CAT in different atmospheres. The results show that metallic inclusions and Ti-concentrated areas in TAS aggregates lead to lower cold mechanical strength in TAS-based castables when fired in air. The performance of the TAS-based castables was similar to that of the CAT-based castables in low-oxygen environments. In the TAS aggregates, titanium suboxide showed local enrichment at the crystal boundary of Al₂O₃ in the form of Ti₂O₃. Both CAT and TAS showed the structural commonalities that aggregates were damaged along the boundary of the main crystal phase after heat treatment in an oxidizing atmosphere.

Abstract

In this paper, the variation of suspension stability under the electric field was studied. Ceramic suspensions such as YSZ/acetyl acetone, YSZ/1propanol, and SnO₂/ethanol were analyzed by applying different voltages. The novel turbidimetry technique was employed to illustrate the stability changes versus electrophoretic deposition (EPD) time. Macro-photography was employed to study the colloidal stability before and after EPD. Also, the weight of the deposited particles was measured. Particles in the suspension were sediment after applying voltage, making the suspension transparent in our deposition cell, especially at 100 V. The electrical conductivity of suspension increased by applying the electric field, showing a peak at 100 V. The suspension conductivity measurements also revealed a peak at 100 V. The occurred transparency became more in-depth over time. As suspension stability is an essential factor for a successful EPD process, the electric field-assisted agglomeration of particles should be considered in tests to reach repeatable results. Our research showed that despite the use of high voltage in routine EPD research, the instability of suspensions and its effect on the results of the coating should be considered.

Graphical abstract

Over the past decade, oxy-fluoride glasses are the subject of investigation by many researchers. Calcium fluoride incorporated alumina-bismuth borate glasses reinforced with minute quantity of copper ions have been synthesized by melt-quenching process and the amorphous nature is approved by X-ray diffraction (XRD) spectra. The samples are further analyzed, to know the effect of Al₂O₃ on CaF₂-Bi₂O₃-B₂O₃–CuO glasses, with the help of density, molar volume, optical, electron paramagnetic resonance (EPR), and Raman and Fourier transform infrared (FTIR) spectra. A decreasing trend was observed in density values with increasing Al₂O₃ even though the relative density of Al₂O₃ is higher than the CaF₂. This decrease in density is attributed to the larger bond length of Al-O in AlO₄ units as compared to B-O bond length in BO₃ and BO₄ units. The bandgap values estimated from optical absorption spectra were found to increase with Al₂O₃ content, indicating the decrement in the number of non-bridging oxygens. Spin-Hamiltonian parameters ({g}_{parallel })>({g}_{perp })>({g}_{mathrm{e}}) (({g}_{mathrm{e}}) = 2.0023) and ({A}_{parallel }) (>{A}_{perp }) are of the opinion that the Cu²⁺ ions were taken the positions of octahedral sites with tetragonal distortion and ground state being ({d}_{{mathrm{x}}^{2}-{mathrm{y}}^{2}}) orbital. FTIR and Raman spectra suggested that these glasses are composed of BiO₆, BO₃, BO₄, and alumina polyhedral.

Abstract

Abstract

Optical properties and gamma-ray attenuation competence of bismo-tellurite sodium titanium zinc glass samples with chemical formula (80 − x)TeO₂–10ZnO–5TiO₂–5Na₂O–xBi₂O₃, where x = 5, 8, 10, 12, and 15 mol% have been explored. Values of optical electronegativity (χ^*) were varied from 0.715 for B5 glass sample to 0.677 for B15 glass sample. Values of linear dielectric susceptibility (χ⁽¹⁾) were varied from 0.400 for B5 glass sample to 0.430 for glass sample. Values of non-linear optical susceptibility (χ³) and non-linear refractive index (left({n}_{2}^{mathrm{optical}}right)) were varied from 4.379 × 10⁻¹² to 5.812 × 10⁻¹² (esu) and from 6.719 × 10¹¹ to 8.656 × 10⁻¹¹ (esu) for B5 and B15 glasses, respectively. The B15 sample with the highest Bi₂O₃ content had the maximum mass attenuation coefficient (µ_m) values across all examined photon energies, while B5 sample with the lowest Bi₂O₃ content had the minimum (µ_m). Both half-value layer (T_0.5) and mean free path (λ) followed the trend as follows: (T_0.5, λ)_B5 > (T_0.5, λ)_B8 > (T_0.5, λ)_B10 > (T_0.5, λ)_B12 > (T_0.5, λ)_B15. The exposure and energy absorption buildup factor (EBF and EABF) values decrease from B5 to B15, demonstrating that the shielding enhancement of glass samples has strengthened. The effective atomic number (Z_eff) parameter followed the trend as follows: (Z_eff)_B15 > (Z_eff)_B12 > (Z_eff)_B10 > (Z_eff)_B8 > (Z_eff)_B5. Our findings confirm that the enhancement of Bi₂O₃ content in the bismo-tellurite sodium titanium zinc glass samples plays an important role of improvement in both optical and gamma-ray protection properties.

Advanced ceramics find significant application areas due to their superior mechanical, electrical, magnetic chemical and thermal properties. By combining these materials, significant properties can be obtained as a result of production of the composites of hard metal compounds in nanoscale dimensions. Self-propagated high-temperature synthesis (SHS) is one of the prominent methods for the production of such nanoparticles. SHS is a combustion synthesis method. In this study, nanocomposite powders of B₄C-TiB₂ were synthesized by SHS method. FactSage software was used for thermochemical simulation and computational stoichiometric optimization. In the experimental step, 2 different SHS sets were prepared. In the first stage, B₄C and TiB₂ powders were synthesized. The B₄C-TiB₂ composite was produced in the final set of experiments. Then, production parameters of B₄C-TiB₂ composite powders, from B₂O₃, TiO₂, and carbon black, were investigated. Magnesium powder was used as reductant agent. Afterwards, HCl leaching process was performed, and acid concentration was optimized. The effect of carbonic acid and H₂O₂ addition on dissolution of undesired phases was also been investigated as a new method. Products were characterized by XRD, SEM and BET analysis. B₄C-TiB₂ composite powder with quite high surface area, fine particle size and high porosity could be synthesized with reasonable purity. According to the results, the optimum molar ratios were determined as TiO₂:B₂O₃:Mg:C = 1:3:12:1.6. Optimum acid concentration was found to be 10.5 M for leaching process, and carbonic acid addition on leaching step found to be effective on TiO₂ removal. The highest purity could be obtained with 50%-50% stoichiometry. It has also been determined that the synthesis of B₄C-TiB₂ composite powder has a positive effect on both the chemical content and the morphology that will increase the sintering ability.

Abstract