Sharif Digital Repository

By a single-step supercritical hydrothermal synthesis method, yttrium oxide nanoparticles were successfully prepared without additional treatment. Yttrium oxide nanoparticles were employed as an adsorbent to study the adsorption of some heavy metal ions. This study revealed that nano structure yttrium oxide was an effective adsorbent for removal of lead ions from aqueous solutions  

Distributed power generation and the ever-growing load demand have caused fault current levels to exceed the nominal rating of the power system devices, and fault current limiters are more needed. Superconducting fault current limiter (SFCL) forms an important category of current limiters. In this paper, a novel flux-based model for the inductive shield-type high-temperature SFCL is developed based on the Bean model. This model is employed to simulate the SFCL performance in a sample circuit. Utilizing the model, the signal characterization of the limited current is determined. A prototype laboratory scale SFCL has been fabricated with superconducting rings. Yttrium barium copper oxide... 

Yttria-stabilized tetragonal zirconia polycrystals (Y-TZP) have been widely applied in fixed partial prostheses as well as dental uses i.e. a substructure for crowns. However, Y-TZP has limited applications, which is due to the presence of defects in its microstructure introduced during the manufacturing process. Accordingly, due to Y-TZP limitations, the novel (X)Y-TZP- 20Al2O3-(80-X) SiO2 (X = 65, 70 and 75) ceramic nanocomposites were successfully fabricated via the powder metallurgy method. X-ray diffraction (XRD) patterns of commercial powders showed the stabilization of monoclinic zirconia (ZM) by increasing the silica content. In order to determine the fracture load and micro-bending... 

We report on the response of a monolithic high Tc transition-edge bolometer to about 3 mmWave for the first time. The detector structure consisting of 400-nm YBa2Cu3O7-x(YBCO) film on buffered yttria stabilized zirconia substrate without any coupled antenna, shows bolometric type responsivity to the 3-mmWave radiation at its transition temperature. The YBCO thin film Ce0.9La0.1O2 buffer layer are both fabricated by the metal-organic deposition method. The meander line pattern of the bolometer is designed for obtaining maximum absorption and responsivity possible when the polarized radiation of the source is aligned with the pattern. Meander lines are 50 micrometers wide and 1.5-mm long. We... 

Monitoring the oxygen in the fume and controlling its amount at high temperatures is an efficient way to regulate combustion efficiency. Zirconia can be an attractive candidate for use in oxygen sensors due to its good physical and chemical properties. The crystal structure of pure zirconia nanopowder due to the lack of cubic phase cannot be used for the fabrication of gas sensor electrodes. Moreover, the change of temperature during ceramic processing and application can promote structural and phase stresses. In this work, to achieve a pure cubic phase, yttria was successfully added to zirconia by a large-scale and effective method called Pechini. The yttria-stabilized zirconia nanopowders...