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Showing 2 results for A. Nemati

A. Nemati, K. Pourazarang,
Volume 5, Issue 3 (Summer 2008 2008)

Abstract: The PZT-based ceramics with a composition of Pb1.1-xLax (Zr0.53Ti0.47)O3, were prepared by conventional mixed oxide followed by mechanical alloying and sol-gel methods in which x was chosen in the range of 0.02–0.06. The samples were calcined in the range of 450 °C - 750 °C for 4h. The physical and electrical properties of the samples were determined as a function of the calcination temperature. The obtained data from two methods were compared with conventional mixed oxide method. Microstructural and compositional analyses of the samples were carried out using XRD and SEM. Dielectric properties of the samples were measured with an impedance analyzer. The ferroelectric properties of the PZT and PLZT samples were measured using the frequencies applying equipment and d33 tester. The results indicated a complete tetragonal phase prepared from both methods. It was shown that the addition of La and reduction in calcination temperature improved both the dielectric and piezoelectric properties. The dielectric constant tended to increase with doping content, giving the maximum value of about 2000 at 3 mol% La3+. In addition, the mechanical coupling factor (Qm) of the doped samples showed a significant decrease. Finally, the value of planar coupling factor (kp) reached the maximum value of 0.47 at 1 mol% La3+.
J. Jac Faripour Maybody, A. Nemati, E. Salahi,
Volume 10, Issue 2 (June 2013)

In the present study, bioceramic composites based hydroxyapatite (HAp) reinforced with carbon nanotubes (CNTs) was synthesized via sol-gel technique. The dried gels were individually heated at a rate of 5°C/min up to 600°C for 2 h in a muffle furnace in order to obtain HAp-MWCNTs mixed powder. Composites were characterized by XRD, FT-IR, SEM, TEM/SAED/EDX and Raman spectroscopy techniques. Results showed the synthesis of HAp particles in the MWCNTs sol which was prepared in advance, leads to an excellent dispersion of MWCNTs in HAp matrix. Apparent average size of crystallites increased by increasing the percentage of MWCNTs. The average crystallite size of samples (at 600°C), estimated by Scherrer’s equation was found to be ~50-60 nm and was confirmed by TEM. MWCNTs kept their cylindrical graphitic structure in composites and pinned and fastened HAp by the formation of hooks and bridges.

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