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Phase Field Simulation of Microstructure Ternary Eutectic Solidification
, M.Sc. Thesis Sharif University of Technology ; Tavakoli, Rouhollah (Supervisor)
Abstract
Physical and mechanical properties of cast alloys is partly a function of the morphology and volume fraction of phases from freezing. The microstructure of the eutectic solidification is function of physical properties (especially mobility and surface tension) and the volume fraction of phases involved in the evolution. The prediction of solidification microstructures will be very helpful for improving the mechanical properties of casting alloys and designing of new families of alloys. The theoretical study of the formation of eutectic microstructures is very difficult and almost impossible in general cases and empirical studies are expensive. The purpose of this study is to predict the...
Controlling morphology and structure of nanocrystallineVcadmium sulfide (CdS) by tailoring solvothermal processing parameters
, Article Journal of Nanoparticle Research ; Volume 13, Issue 7 , 2011 , Pages 3011-3018 ; 13880764 (ISSN) ; Mohammadi, M. R ; Sharif University of Technology
2011
Abstract
Cadmium sulfide (CdS) with different morphologies was successfully prepared by solvothermal process by controlling the processing parameters, including nature of precursor and solvent, reaction temperature and process time. X-ray diffraction patterns revealed that, in all cases highly pure and crystallized CdS with hexagonal structure were obtained. In addition, it was found that the processing parameters influence on preferable growth direction of CdS nanostructures. Field emission scanning electron microscope analysis showed that CdS nanowires with different aspect ratios were obtained (depending upon the reaction temperature and process time) in presence of sulfur powder and...
Preparation and Characterization of Nanocrystalline One-dimensional Cadmium Sulfides by Solvothermal Process for Solar Cell Application
, M.Sc. Thesis Sharif University of Technology ; Mohammadi, Mohammad Reza (Supervisor)
Abstract
One-dimensional (1D) cadmium sulfide (CdS), nanostructures have significant potential applications in solar cells, photocatalysts and many electronic devices. There are many experimental approaches to synthesis 1D CdS nanostructures. Among them solvothermal method has many advantage such as controllable and inexpensive method. 1D CdS nanostructures with different properties in morphology, crystal structure, band gap energy and etc can be obtained by controlling solvothermal processing parameters. In the present work the effect of solvothermal processing parameters including reaction temperature (120ºC ,160ºC and 200ºC), process time (12h, 48h and 72h), sulfur source (S powder, Thiourea and...
One-dimensional cadmium sulfide (CdS) nanostructures by the solvothermal process: Controlling crystal structure and morphology aided by different solvents
, Article Materials Letters ; Volume 65, Issue 9 , 2011 , Pages 1291-1294 ; 0167577X (ISSN) ; Mohammadi, M. R ; Fray, D. J ; Sharif University of Technology
2011
Abstract
Cadmium sulfide (CdS) nanowires and nanorods with different aspect ratios were successfully synthesized by the solvothermal method aided with various solvents, namely ethylenediamine, ethanolamine and triethylene tetraamine. X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) analyses revealed that, highly pure CdS nanostructures were crystallized with different structures and preferable growth orientations depending on solvent nature. Field emission electron microscope (FE-SEM) images showed that the aspect ratio of CdS nanostructures depends upon the dielectric constant and boiling temperature of solvents. CdS nanostructures with the highest aspect ratio in the form...
Drying shrinkage in alkali-activated binders – A critical review
, Article Construction and Building Materials ; Volume 190 , 2018 , Pages 533-550 ; 09500618 (ISSN) ; Kinnunen, P ; Dalvand, A ; Mohammadi Firouz, R ; Illikainen, M ; Sharif University of Technology
Elsevier Ltd
2018
Abstract
Alkali-activated binders have been proposed and have emerged as an alternative to ordinary Portland cement (OPC) binders with acceptable mechanical and durability performances in addition to positive environmental impacts. These alternative binders use a wide range of aluminosilicate precursors, with differing availabilities, reactivities, costs and CO2 emissions. Despite all the studies published on improving the characteristics of these materials in the last decades, some aspects of alkali-activated binders require further investigations. For instance, shrinkage in alkali-activated binders due to the different chemical processes being involved is more complicated than OPC composites and it...