Papers by Keyword: Molten Salt Method

Abstract: Microbial resistance has become a threat that causes thousands of deaths yearly; therefore, efforts are required to address this problem. One of the promising methods used to inhibit bacterial growth is photocatalyst technology. In this research, CaTiO₃ compounds was synthesized using the molten salt method and tested for antibacterial activity in both UV-unexposed and UV-exposed conditions on Staphylococcus aureus bacteria. The diffractogram showed that the CaTiO₃ compound was successfully synthesized without impurities that indicated by the characteristic peaks at 2θ (^o) = 23.29; 33.18; 47.52; 59.33; 69.48; 79.17. The micrograph results showed that the CaTiO₃ compound had a regular polyhedral shape and was agglomerated with particle sizes in the 0.2941 ± 0.0144 µm range. The UV-Vis DRS spectra showed that the CaTiO₃ compound had a bandgap energy of 3.48 eV (315 nm). In the antibacterial activity test results under UV irradiation, the growth of Staphylococcus aureus decreased by 3.95, 0.91, and 1.45 CFU/mL.

Abstract: In this research, the Ba(Zr_0.05Ti_0.95)O₃ powders were prepared by molten salt method. The powders were calcined at 600-1100°C for 3 h with heating rate of 5°C/min. The BZT powders were synthesized by molten salt method to reduce the calcination temperature by up to 300°C. The sintering procedure was carried out at 1250°C for 2 h with a heating/cooling rate of 5°C/min. Phase formation and microstructure were examined by XRD and SEM, respectively. The influence of the CuO additive on density and dielectric properties were investigated. The density of the sintered samples was measured by Archimedes method with distilled water as the fluid medium. Dielectric properties were examined by LCR meter. The BZT+2.0 mol% CuO ceramic sintered at 1250°C showed the highest density of 5.76 g/cm³, and the room temperature dielectric constant and dielectric loss at 1 kHz were 2687 and 0.01, respectively.

Abstract: In this study, the physical properties, dielectric properties, and micro-hardness of (Ba_0.90Ca_0.10)_0.90(Na_0.50Bi_0.50)_0.10TiO₃ or BCT-NBT ceramics prepared by molten salt method with various sintering temperatures were investigated. The powders were calcined at 500-1100°C for 4 h with heating rate of 5°C/min. It was found that the optimum calcination condition was 1000°C for 4 h. These powders were pressed and sintered at 1200-1400°C for 3 h with a heating rate of 5°C/min. The microstructure was examined by scanning electron microscope (SEM). The density of the sintered samples was measured by Archimedes method with distilled water as the fluid medium. Dielectric properties were examined by LCR meter. The micro-hardness of the BCT-NBT ceramics was determined using the Vickers and Knoop indentation techniques. The results showed that the average grain sizes increased with increasing sintering temperatures. At sintering temperatures higher than 1200°C, the fracture mode changed from partial intra-granular to mainly intra-granular. The sintering temperature at which the density, dielectric and hardness properties were maximal was 1350°C. The highest density was about 5.4 g/cm³, and the Vickers and Knoop micro-hardnesses were 6.6 and 6.4 GPa, respectively. The dielectric constant at the Curie temperature was 3682 and the dielectric loss was 0.01 at 1 kHz frequency.

Abstract: Plate-like Magnesium Aluminum spinel (MgAl₂O₄) with octahedral structure was synthesized using Al₂O₃ plate-like particles and MgO powders as raw materials in the molten salt of LiCl, KCl or NaCl, respectively. The Results indicated that the molten salts accelerated MA formation, and LiCl was more effective than KCl and NaCl, which may be attributed to the higher solubility of MgO in the former than in the latter two. The outline shape of MA spinel product phase was the same as that of original plate-like Al₂O₃ particles. The growth mechanism of plate-like MgAl₂O₄ spinel particles with octahedral structure should be governed by “template formation mechanism” accompanied with “dissolution-precipitation mechanism”.

Abstract: Titanium silicon carbide (Ti₃SiC₂) were obtained by molten salt synthesis method using the Ti-Si-Fe alloy extracted from high titania blast furnace slag and natural graphite as the raw materials. The phase composition, microscopic structure of the products were characterized by powder X-ray diffraction, scanning electron microscope and transmission electron microscope. The influence of firing temperature and chloride salts species on the phase and morphology of the products were investigated. The results indicated that the synthetic temperature of Ti₃SiC₂ by molten salt synthesis method was about 100 °C, which was lower than that without molten salts. The “dissolution-precipitation” mechanism governed the overall molten salt synthesis process. The lamellar Ti₃(Si,Al)C₂ crystal growth obeyed by a two-dimensional ledge growth mechanism.

Abstract: This research studied the effect of the different preparation technique on phase transition and electrical properties of Ba_0.8Sr_0.2TiO₃. The samples compared 3 preparation technique, there are conventional mix-oxide, molten-salt and seed-induced method. The samples prepared by molten-salt calcined at 800 °C, the samples prepared by conventional mix-oxide and seed-induced method was calcined at 1200 °C for 3 h. All of samples sintered at 1400 °C for 3 h. The phase formation and morphology of samples were characterized via X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. The dielectric properties of the samples were measurement by LCR-meter.

Abstract: In the research, the properties of potassium sodium niobate – barium titanate [(1-x)K_0.02Na_0.98NbO₃–(x)BaTiO₃: (1-x)KNN–(x)BT] ceramics prepared by molten salt method with various molecular weight of BT or x are 0 and 0.05 were investigated. The calcined powders of pure K_0.02Na_0.98NbO₃ and (0.95) K_0.02Na_0.98NbO₃-(0.05) BaTiO₃ were pressed and sintered at 1250 – 1325 °C and 1225 – 1300 °C for 2h, respectively. It was found that, the samples showed phase structure changing from monoclinic to orthorhombic with small amount BaTiO₃ addition. The densification of K_0.02Na_0.98NbO₃ ceramics and dielectric properties were improved with the addition of BaTiO₃. The (0.95)K_0.02Na_0.98NbO₃–(0.05)BaTiO₃ ceramics sintered at 1250 °C showed maximum density and dielectric constant (∼8035), which was even comparable with that of K_0.02Na_0.98NbO₃ ceramics sintered at 1225 – 1300 °C.

Abstract: Ba_0.85Ca_0.15Zr_0.1Ti_0.9O₃ (BCZT) ceramics were produced by using the seed-induced method. The nano-particle BZ (BaZrO₃) seeds were mixed with BaCO₃, CaCO₃, ZrO₂ and TiO₂ powder for preparing by the mixed oxide method. The XRD results indicated that all powder and sintered ceramic samples showed a pure perovskite phase with coexistence between rhombohedral and tetragonal phase. As the BZ seed content increased, the density of ceramics tended to decrease from 5.61 g/cm³ to 5.37 g/cm³. The average grain size of the ceramics was in the range of 12.15 -13.50 mm. The dielectric loss (tand) was less than 0.03 for all samples at room temperature (at 1 kHz). Other electrical properties, including dielectric constant (ε_r), remnant polarization (P_r), and piezoelectric charge coefficient (d₃₃) values decreased with increasing BZ seed doping with relates to the decreasing grain size and density of BCZT ceramics. However, the values of coercive field (E_c) decreased and piezoelectric voltage coefficient (g₃₃) increased with BZ seed doping.

Abstract: Zircon whiskers were synthesized via non-hydrolytic sol-gel process combined with molten salt method by using anhydrous zirconium tetrachloride as zirconium source, TEOS as silicon source, anhydrous ethanol as solvent, and sodium molybdate as molten salt. The effects of heat treatment mode and cooling rate on the synthesis of zircon whiskers have been studied by means of XRD, FE-SEM, TG and TEM. The results indicate that well-developed whiskers can be prepared through heat treating the sample at 850°C for 3 h followed by a furnace cooling process. The zircon whiskers which were fabricated by this heat treatment mode grew along the [001] direction and showed diameter of 50~100 nm and aspect ratio of 20~30.

Abstract: Mullite whiskers were prepared via non-hydrolytic sol-gel process combined with molybdate molten salt using tetraethoxysilane and anhydrous aluminum chloride as precussor, anhydrous ether as oxygen donor, molybdate as molten salt. The effects of heat treatment temperature, molten salt amount, holding time on synthesis and morphology of mullite whiskers were investigated by X-ray diffraction (XRD) and field emission scanning electron microscopy (FE-SEM). The results show that the mullite whiskers appeared at the lowest temperature of 800°C, and optimized mullite whiskers could be prepared at 900°C for 8 h with the mass ratio of xerogel and molybdate as 1:2, the diameter of the whiskers was in the range of 0.15-0.22 μm with the aspect ratio of more than 40.