فهرست مطالب

Advanced Ceramics Progress - Volume:3 Issue: 4, Fall 2017

Advanced Ceramics Progress
Volume:3 Issue: 4, Fall 2017

  • تاریخ انتشار: 1396/08/30
  • تعداد عناوین: 7
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  • J. F. M. Ibrahim *, A. Mergen, E. Lhan Sahin, H. S. Basheer Pages 1-5
    Single phase Eu doped GdMnO3 ceramics were prepared using solid state reaction route. Several different characterization techniques were used to investigate the structural and magnetic properties of the samples, including X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDX) and Vibrating Sample Magnetometer (VSM). All samples indicated single phase which confirmed by XRD and SEM. Magnetic measurements of the doped samples at low temperature (10K) revealed the existence of ferromagnetic order with certain doping concentration which could be possibly due to slight structural distortion in the lattice. Eu doped GdMnO3 could be the potential candidate for multiferroic application exhibiting better ferromagnetic property.
    Keywords: Doping, Multiferroic Materials, GdMnO3 Ceramics, Solid State Reaction, Magnetic Properties
  • S. Ebrahimi, B. Yarmand *, N. Naderi Pages 6-12
    Zinc sulfide (ZnS) films were deposited through a simple and low cost spray pyrolytic technique using mixed aqueous solutions of zinc nitrate and thiourea. The structural and optical properties of these films were investigated as a function of initial (Zn:S) molar ratio in the precursor solution, which varied between (1:1) and (1:3). X-ray diffraction (XRD) analysis revealed that wurtzite zinc oxide (ZnO) and cubic ZnS phases formed in the film prepared by the equal molar ratio of zinc to sulfur ions and with increasing sulfur content in the precursor solution, only single cubic ZnS phase was appeared. The transmittance spectra measured by UV-Vis spectrophotometer indicated that with the increment of the sulfur content, the transmittance of the films increased in the visible and near infrared regions about 50% and the absorption edges shifted to shorter wavelengths. As a result, the band gap energy (Eg) increased from 3.43 to 3.72 eV and the band tail width (Eu) decreased from 553 to 259 meV, which is due to the phase composition and the decrement of structural defects. By extracting a linear relevance between the band gap energy and width of the band tail of ZnS, the optical band gap at Eu= 0 was estimated to be 3.977 eV.
    Keywords: ZnS, spray pyrolysis, zinc to sulfur molar ratio, band gap energy, width of Urbach tail
  • F. Shojaeepour, M. Kazemzad Asiabi *, M.R. Rahimpour, Ali Khanlarkhani Pages 13-20
    Pseudomorphism is known as a suitable technique for producing mesoscale pore in silica powders keeping their original morphologies. Herein, silica discs with several millimeter dimensions have been prepared using the same method. This method has been utilized through application of pseudomorphism reaction of preshaped bodies by immersion in a solution containing surfactant and swelling reagents. The pseudomorphism reactions were performed on time and temperature controlled condition. Large surface area of mesoporous silica discs have been considered here for investigation in methane steam reforming as catalyst support. The silica support has been utilized for preparation Ni-silica catalyst through impregnation method. The physical properties of synthesized mesoporous support and nanocatalysts have been characterized by nitrogen adsorption-desorption surface measurement (BET- BJH method) and Archemideous immersion analysis as well as field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), inductively coupled plasma (ICP) analyses techniques. Investigation on catalytic behavior of prepared samples in steam reforming of methane resulted improving of methane conversion in addition to hydrogen production yield.
    Keywords: Mesoporous silica, Pseudomorphism, catalyst, methane reforming
  • M. Heydari *, M. Sarmast, M.R. Vaezi, A. A. Behnam Ghader, A. H. Pakseresht Pages 21-24
    In this work, hydroxyapatite/silica nanopowders were granulated to fabricate plasma sprayable feedstocks. For this purpose, the wet powders obtained by heating a hydroxyapatite/silica slurry were stirred and sieved. To realize the feedstock application in the plasma spray process, powders were deposited on titanium substrate. The morphology of granulated feedstock and sprayed coating was studied using field emission scanning electron microscopy (FESEM). The evaluation of sprayable powder such as apparent density and flow rate of feedstock was performed according to ASTM nos. B 212-99 and B 213-03 standards. The results demonstrated that the granules were spherical and semi-spherical in shapes. The apparent density and flow rate of granulated feedstock were 540 kg/m3 and 0.1089 gr/sec, respectively. Also, the granules yielded the coating with molten/unmolten regions and porosity.
    Keywords: Nanocomposite, Coating, Plasma Spray, Hydroxyapatite, Silica
  • M. M. Kalantarian *, S. Asgari Pages 25-33
    Lithium iron orthosilicate (Li2FeSiO4) with Pmn21 space group is theoritically investigated as a chathode material of Li-ion batteries using density functional theory (DFT) calculations. PBE-GGA (+USIC), WC-GGA, L(S)DA (+USIC) and mBJ+LDA(GGA) methods under spin-polarization ferromagnetic (FM) and anti-ferromagnetic (AFM) procedure are used to investigate the material properties, including structural parameters, theoretical reaction voltage (TRV), magnetic state and electerical properties (based on density of states, DOS). Theoretical structural assessments carried out in this research imply electrochemical reversibility and structural stability of Li2FeSiO4. Based on DFT calculations, switch between magnetic states are proposed to account for the experimentally observed extra oxidation voltage in the first cycle.
    Keywords: lithium-ion, battery, cathode, Li2FeSiO4, DFT
  • M. Behtaj, P. Sangpour * Pages 34-40
    α‒Fe2O3/MoS2 nanocomposites were synthesized via hydrothermal method and characterized in terms of crystal structure, particle size and morphology, elemental purity and optical properties. Results confirmed the formation of α‒Fe2O3/MoS2 nanocomposites containing hematite nanoparticles with average diameter of 40 nm and MoS2 nanosheets with hexagonal crystal structure and sheet thickness of < 10 nm. Optical band gap measurements revealed decrease of the band gap of α‒Fe2O3 nanoparticles from 2.65 to 2.15 eV upon loading MoS2 nanosheets. The as‒synthesized α‒Fe2O3/MoS2 nanocomposites showed a high absorption capability in the visible irradiation. Photocatalytic examinations showed over 98 % degradation of Rhudamine Blue (Rh B) organic dye within 75 min. α‒Fe2O3/MoS2 nanocomposites enhanced the rate of degradation as compared to pure α‒Fe2O3 nanoparticles and MoS2 nanosheets.
    Keywords: ?-Fe2O3-MoS2 Nanocomposite, Photocatalytic activity
  • R. Nasrollahnezhad, H. Majidian *, L. Nikzad, T. Ebadzadeh Pages 41-48
    Corrosion resistance of zircon reinforced alumina refractories has been carried out through static crucible test. The corrosion measurements with percentage, the penetration depth of molten steel and the microstructure of the refractories were evaluated after soaking 150 h at the temperature of 1500˚C. Results showed that the corrosion resistance of alumina increased by adding 20 wt% zircon, and decreased with further increasing of zircon. Also, the samples containing 20 wt% of zircon obtained the minimum porosity. Microstructural features of this composite showed needle-like mullite grains and higher amount of zirconia particles which may be responsible for providing the corrosion resistance to melt penetration.
    Keywords: AMZ composites, zircon, corrosion resistance, phase composition