Iranian Journal of Materials Science and Engineering

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Abstract: The direct reduction of copper sulfide concentrate from Iranian Sarcheshme deposits with carbon in the presence of lime was investigated in the temperature range of 800-1000 ºC. The reduction kinetics was determined by means of weight loss measurements. It was found that the rate of reaction increased considerably with increasing the temperature. The kinetics was also improved when large excesses of lime and carbon were present in the mixture. The effects of catalytic additives of Na2CO3 and K2CO3 were also investigated. It was realized that the rate of reaction increased by higher concentrations of additives. X-ray diffraction analysis of reduced samples revealed that sulfur was fixed as solid CaS, and metallic copper was formed.

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Abstract: Auto-ignited gel combustion process has been used for producing a red hematite-zircon based pigment. The combustible mixtures contained the metal nitrates and citric acid as oxidizers and fuel, respectively. Sodium silicate (water glass) was used as silica source for producing zircon phase. X-Ray Diffractometery, Electron Microscopy and Simultaneous Thermal Analysis were used for characterization of reactions happened in the resulted dried gel during its heat-treatment. L* a* b* color parameters were measured by the CIE (Commission International de I'Eclairage) colorimetric method. This research has showed that solution combustion was unable to produce coral pigment as the end product of combustion without the need for any further heat treatment process.

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An actuator is a device that converts input energy into mechanical energy. According to various types of input energy, various actuators have been advanced. Displacement in the electromagnetic, hydraulic and pneumatic actuators achieve by moving a piston via electromagnetic force or pressure, however the piezoelectric actuator (piezoceramic plates) displace directly. Therefore, accuracy and speed in the piezoelectric device are higher than other types of actuators. In the present work, the high-field electromechanical response of high-quality (1−x)(Bi 0.5Na0.5)TiO3–x(Bi0.5K0.5)TiO3 samples abbreviated to BNKTx with x = 0.18, 0.20, 0.22 and 0.24 ceramic materials across its MPB was investigated. The piezoelectrics and actuation characteristics were characterized. Ourresults indicate that x = 0.20, indeed, constitutes the best choice for the MPB composition in the system. Maximum of remanent polarization (37.5 μC cm−2) was obtained for x=0.20. High-field electromechanical responses were also obtained for BNKT0.20 samples. This material exhibited giant field induced strains of 0.13% under 1 kV mm -1 at room temperature.

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Porous nanostructured SnO₂ with a sheet-like morphology was synthesized through a simple green substrate-free gelatin-assisted calcination process using Tin tetracholoride pentahydrate as the SnO₂ precursor and porcine gelatin as the template. Crystalline phase, morphology, microstructure, and optical characteristics of the as-prepared material were also investigated at different calcination temperatures using X-ray diffraction (XRD), Field emission scanning electron microscopy (FESEM), UV-visible absorption, and Photoluminescence spectroscopy (PL), respectively. XRD patterns of all the samples revealed the presence of a tetragonal crystalline structure with no other crystalline phases. Moreover, the synthesized hierarchical sheets assembled with nanoparticles displayed a large surface area and porous nanostructure. The calculated optical band gap energy varied from 2.62 to 2.87 eV depending on the calcination temperature. Finally, photoluminescence spectra indicated that the nanostructured SnO₂ could exhibit an intensive UV-violet luminescence emission at 396 nm, with shoulders at 374, violet emission peaks at 405 and 414 nm, blue-green emission peak at 486 nm, green emission peak at 534 nm and orange emission peak at 628 nm.