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Synthesis and properties of Fe-Pd Shape Memory thin Films by Electrodeposition

Rezaei, Milad | 2010

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 40825 (07)
  4. University: Sharif University of Technology
  5. Department: Materials Science and Engineering
  6. Advisor(s): Ghorbani, Mohammad; Dolati, Abolghasem
  7. Abstract:
  8. In this study, an alkaline bath for co-deposition of Fe and Pd was selected. In order to investigate the mechanism of deposition, each of the metals iron and palladium electrodeposited from selected bath separately; and the kinetics of electrodeposition by electrochemical techniques such as linear voltammetry, cyclic voltammetry, chronoamperometry and chronopotentiometry were evaluated. Electrodeposition processes of Fe, Pd and their alloy were irreversible and under diffusion of reducing agents are controlled. Moreover the electroreduction of palladium from utilized bath was performed in two steps. At following, the mechanism of iron– palladium alloy electrocrystallization was discussed and it turned out that the nucleation of alloy is instantaneous which is associated with the growth of three-dimensional hemisphers. It also revealed that at low overpotentials, the alloy deposition process was controlled by palladium reduction while at higher overpotentials the reduction of iron is governed the process. The alloy films on the substrates include copper; brass and FTO/glass were deposited. Then the alloy plating parameters such as cathode current efficiency and chemical composition of alloys were determined; the bath efficiency is low and at maximum reaches to 34% on brass substrate. The alloy films in a wide range of chemical composition from 12.1 to 93.2 atomic percent of iron were deposited at different electrodeposition potentials. The chemical composition of alloy was demonstrator an anomalous co-deposition. The grain sizes of obtained deposits by AFM microscope were measured and were between 54 to 129 nm. The created layers were annealed and their surface morphology by SEM, FESEM and AFM microscopes were investigated. Crystallographic structure and the obtained phases during the deposition and also during annealing heat treatment were determined by XRD method. Then the films with chemical composition about 30 atomic percent of palladium were exposed under annealing - Quench heat treatment and shape memory behavior were investigated by XRD and DSC methods. Then the deposits by VSM magnetometer have been investigated and the magnetic parameters of alloy films such as magnetic saturation and coercivity force, before and after annealing were measured. Finally the presence of magnetoresistance property in deposits has been shown
  9. Keywords:
  10. Electrochemical Deposition ; Kinetics Study ; Magnetic Properties ; Shape Memory Thin Film ; Iron-Palladium Thin Film ; Nanostructural Thin Films

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