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Investigation on Parameters of Carbon Nanotubes Growth and Effect of Interaction between H2 Gas and their Surfaces and Determining Capacity of Hydrogen Storage
, Ph.D. Dissertation Sharif University of Technology ; Moshfegh, Alireza (Supervisor) ; Nozad, Ahmad (Supervisor)
Abstract
In this study, growth of MWCNTs in form of thin film and powder for hydrogen storage was investigated. Different analytical techniques including SEM, TEM, STA, XRD, XPS, BET, BJH and Raman spectroscopy were applied to characterize the samples. The results showed that substrate, catalyst thickness and type of catalyst are influenced in yield of the growth, structure and quality of MWCNTs. The study has also indicated that MWCNTs grown on Fe-Pd bimetallic catalyst with 25-75 proportion had the highest growth yield. Moreover, decreasing of the growth temperature from 970 to 920 oC produced single-walled carbon nanotubes (SWCNTs) with high quality (IG/ID = 15.8) and low growth yield....
Study of Nanocrystallization Kinetics, Microstructure and Magnetic Properties of Finemet-type Soft Magnetic Materials
, Ph.D. Dissertation Sharif University of Technology ; Madaah Hosseini, Hamid Reza (Supervisor) ; nozad, Ahmad (Supervisor) ; Beitollahi, Ali (Co-Advisor)
Abstract
Nanocrystallization kinetics of amorphous Finemet-type alloys was studied using Isokinetic and Isoconversional methods (Kissinger model-fitting method, Vyazovkin advance method, Kissinger–Akahira–Sunose(KSA),Flynn–Wall–Ozawa(FWO),Tang and Starink) under isothermal and non-isothermal conditions. Effects of chemical composition on the nanocrystallization kinetics, microstructure and magnetic properties of Fe73.5Si13.5B9Nb3Cu1 and Fe77Si11B9Nb2.4Cu0.6 alloys were also investigated. Kinetic triplet (activation energy, frequency factor and reaction model) were determined by these methods and compared for the alloys. According to isoconversional methods, the activation energy is variable as a...