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Title:	Physical and magnetic properties of erbium-substituted yttrium iron garnet thin film prepared via sol-gel technique
Authors:	Ramadan Ebrahim Ali Shaiboub
Supervisor:	Mustaffa bin Hj Abdullah, Prof.Dr.
Keywords:	Universiti Kebangsaan Malaysia -- Dissertations Dissertations, Academic -- Malaysia Yttrium iron garnet. Garnet-Magnetic properties. Magnetic resonance. Thin films-Magnetic properties
Issue Date:	26-Apr-2012
Description:	Erbium-substituted yttrium iron garnet (Er-YIG) films of composition ErxY3-xFe5O12 (0 ≤ x ≤ 3) were prepared via a sol-gel method at different annealing temperatures varying from 800 to 1000 °C. Temperature of 800 °C was chosen as the starting temperature for the preparation of Er-YIG films due to a better garnet phase formed as observed by X-ray diffractometer (XRD) analysis. The goals of this research were the preparation and studies of the structural, magnetic and magneto-optical (MO) properties of the Er-YIG films. The YIG precursor sol was prepared using nitrates of Y(NO3)3.6H2O, Fe(NO3)3.9H2O, and Er(NO3)3.5H2O as the raw materials. 2- methoxyethanol and acetic acid were used as solvents. The whole process was carried out under reflux condition. The gel was transformed into film onto a quartz substrate using the spin coating technique. The rate of the spinning process was 3500 rpm and it was done for 30 seconds. Then the films were annealed from 800 to 1000 ° C in airfor 2 hours. The nanostructures of all the samples at different annealing temperatures were characterized by XRD, the magnetic properties and the grain size were studied using a vibrating sample magnetometer (VSM) and a field emission scanning electron microscope (FESEM), respectively. The MO properties were characterized using a spectrophotometer-UV and a Faraday rotation (FR) experimental set-up. The X-ray diffractions of the filmsshow a number of diffraction lines corresponding to the cubic garnet phase. The crystallizationof the films is more complete as the annealing temperatures increased. The lattice constants of ErxY3-xFe5O12 (0 ≤ x ≤ 3)films decrease from 12.364 Å to 12.338 Å, 12.355 Å to 12.339 Å and 12.354 Å to 12.315 Å as Y is completely substituted by Er for annealing temperature of 800, 900 and 1000 °C, respectively. The FESEM micrographs for all samples annealed at temperatures of 800, 900 and 1000 °C exhibit highly agglomerated particles having an average particle size of 48, 58 and 86 nm, respectively. The average values of crystallite size are almost equal at different annealing temperatures and are smaller than the particle size. The average values of saturation magnetization (Ms) and the coercivity (Hc) decrease with increasing Er contentand increase at each annealing temperature. The results of the optical characterization show that the absorption coefficient increases with the annealing temperature.Faraday rotation at wavelength of 633 nm increases with the increase of magnetic field and Er content. In conclusion, Er-YIG films have been successfully prepared by sol-gel method. The increase of annealing temperature increases the crystallization, particle agglomeration and also absorption coefficient of the films. The increase of Er content increases the Faraday rotation but reduces the saturation magnetization and coercivity values of the films.,'Certification of Doctoral Thesis' is not available,Ph.D
Pages:	159
Call Number:	QC766.F3S533 2012 tesis
Publisher:	UKM, Bangi
Appears in Collections:	Faculty of Science and Technology / Fakulti Sains dan Teknologi

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