نشریه علم و مهندسی سرامیک
سال دوازدهم شماره 1 (پیاپی 44، بهار 1402)

We report the electronic, structural and optical properties of topological insulator SnBi2Te4 calculated by means of linear augmented plane waves with full potential (FP-LAPW) within the framework of density functional theory (DFT) implemented in Wien2k code. Bulk band gaps of 0.36eV and 0.22eV are predicted by using PBE and LDA approximations, respectively. These gaps indicated that SnBi2Te4 is potentially suitable for room temperature electronics applications. The results are in accordance with other works.

Mesoporous manganese oxide nanoparticles were prepared using SBA-15 hard silica template (SBA-MnO2) and were investigated as electrode material for electrochemical pseudocapacitors. Also, for comparison, mesoporous manganese oxide nanoparticles were prepared using pluronic P123 copolymer as a soft template (P123-MnO2). Structural and morphological characterizations of the prepared manganese oxide nanostructured materials were conducted using X-ray diffraction (XRD), nitrogen absorption/desorption test, scanning electron microscope (SEM) and transmission electron microscope (TEM). In addition, electrochemical investigations of the electrode materials were performed using cyclic voltammetry (CV) and galvanostatic charge-discharge (GCD) examinations. The results showed that the SBA-MnO2 active material has a higher specific capacitance (1200 F g-1 in a current density of 1 A g-1) than the P123-MnO2 material (1200 F g-1 in a current density of 1 A g-1) due to its higher specific surface area and more porous structure. Therefore, the mesoporous SBA-MnO2 active material can be introduced as a potential electrode material for high-performance electrochemical capacitors.

In recent years, the synthesis of nanoparticles via the green method attracted more attention from scientists regarding environmental problems. In this work, mesoporous cobalt oxide (Co3O4) nanoparticles (NPs) have been synthesized by the sonochemistry method in the presence of Deep Eutectic Solvent (DES). The effect of DES has been investigated on the morphology of the final product and its photocatalytic performance. Different techniques like XRD, SEM, and nitrogen adsorption-desorption are used to characterize the NPs regarding their crystallinity, structure, and porosity. To investigate the effect of DES, different nanoparticles have been synthesized in the absence of DES and compared with the last sample. The results proved that DES has a considerable effect on the porosity and the size of the nanoparticles. Finally, the performance of the final nanoparticles has been investigated in a sonophotocatalytic process. The Co3O4 NPs synthesized in deep eutectic solvent (DES) exhibited excellent sonophotocatalytic (UV+US) performance, degrading 99.54% of the caffeine in 55 min.

In this research, the production process of YSZ powder for thermal spraying by co-precipitation method is presented, which is divided into two main stages. In the first stage, YSZ material is obtained through a series of processes, including preparing a soluble precursor from the salts that make up the YSZ powder based on stoichiometric ratios, hydrolyzing the precursor, filtering the precipitates, drying the precipitates, and calcining them. After various tests and confirmation of the chemical composition, phase composition, and purity of the synthesized YSZ powder, the first stage is completed. In the second stage, the produced powders undergo the granulation process to increase their flowability and thermal sprayability. Following the completion of the second synthetic stage, YSZ powder is ready for use in thermal barrier coatings. The synthesized powder closely resembles the highly regarded Metco 204NS-G powder, known for its superior performance and final coating structure.

: TaC-HfC composites with various contents of tantalum carbide powder (0, 10, 20, 25 and 30 vol.%) were prepared via pressure less method and sintered at 2200, 2300 and 2400 °C. Physical and mechanical properties of the samples including density, hardness, modulus elastic and microstructure were investigated. In this research, it was found that density increases by rising tantalum carbide percentage in hafnium carbide-based composite and increasing sintering temperature, so that relative density changes from 52.8% in zero vol.% TaC composite to 64.55% in 30 vol.% of it at 2200 °C sintering temperature. Also, the hardness of the samples increased as the sintering temperature and tantalum carbide additives increased. The highest value of the hardness obtained as 26 GPa for the HfC-25 vol.% TaC composite sintered at 2400 °C. Microstructure studies showed less porosity and more density by sintering the composite at higher temperature and TaC content.

As a result of their low weight and significant physical, mechanical and ablation behaviors, the carbon fabric composites and reinforced felt with ultrahigh temperature ceramics (UHTCs) have become the focus of aerospace industries. In this research, carbon fabric composites and resin have been used as matrix and the combination of ZrB2 76 wt%, ZrC 10 wt%, SiC 10 wt% powders as reinforcement and B4C 4% powder has been utilized as additive the mixture of mentioned powders with weight ratio of 25, 50, 75 precent was splashed on the carbon fabric and felt layers. for comparison, samples of 100% ceramic powder and 100% carbon fabric and felt were made as control samples. When the samples become dried up, they were pressed and sintered by pressureless sintering method. The results indicated that increasing the amount of powders led to samples density and shrinkage increase. The highest density is related to the sample without carbon fabric and felt with a relative density of 98.5. Also, the porosity decreased with the increase in the weight percentage of the powder, and the lowest porosity is related to the sample without carbon fabric and felt with a value of 0.5%. In this research, it was found that the lowest linear oxidation is related to the sample containing 75% ceramic powder in the carbon fabric group with a value of 3.17×10-2  (s ) in the felt group.   mm s )  and the sample containing 75% powder with a value of 3.61×10-2 ( mm.

In this study, Fe3O4/SiO2/GO nanocomposites were investigated as a pH-responsive nanocarrier for the loading and release of the anticancer drug curcumin. Fe3O4/SiO2/GO nanoparticles were synthesized by thermal treatment method and characterized and drug delivery properties were investigated using VSM, FTIR, SEM, UV-visible, EDX, and, TEM techniques. The size of Fe3O4/SiO2/GO nanocomposites was about 56 nm. The X-ray diffraction pattern results of Fe3O4/SiO2/GO nanocomposite showed the presence of crystalline, cubic, and tetragonal phases with a crystal size of 14.79 nm, and the VSM results showed the ferromagnetic behavior at room temperature .The results of FTIR analysis and SEM images before and after drug loading confirmed the functionalization of nanocomposites with curcumin. The loading capacity of curcumin on the surface of Fe3O4/SiO2/GO nanocomposites was approximately 19.21%. The curcumin release from nanocarriers increased from 28% to 68% by changing pH from 7.4 to 4.8. Results of the MTT test showed that nanocarriers are significantly toxic on U87 cell lines in a dose-dependent manner, while they are relatively safe for human fibroblast cells.