Details

Study of the strutural and electric properties of garnets ferrimagnetc GdIGXYIG1-X and its aplications in componentes of microwaves.

by Almeida Fechine, Pierre Basílio

Abstract (Summary)
Due to a fast progress in the development of communication systems, the dielectric and magnetic ceramics (ferrites) have become attractive to be used in devices. Although the ferrites of the spinel type were the first material used in the microwave range, garnets have smaller dielectric losses and, therefore, are chosen for many applications. High demands for modern electric applications in magnetic materials results in new techniques and products being permanently studied and researched, with a consequent appearance of new solutions for a wide applications series. In this sense, the research in composites is employed to reach new materials. This work presents the study of the ferrimagnetic composite, constituted by Y3Fe5O12 (YIG) and Gd3Fe5O12 (GdIG) phases, through solid state synthetic route and submitted to high-energy mechanical milling. The X-Ray Diffraction and the Raman, Infrared and Mössbauer Spectroscopy were essential for the structural characterization of the composites. The peculiarities in the morphology of the samples were elucidated by Scanning Electron Microscopy and Vickers Microhardness. Additionally, experiments were made in order to evaluate the electric and magnetic behavior of the composites at radio frequency and microwave range and then later suggest an adequate technological application. The composites were efficient as ferrite resonator antennas (FRAs) and microstrip antennas (thick films deposited on metalized surface alumina substrate by screen-printing technique), in the microwave frequency range. The experiments with FRAs showed satisfactory due to the control of the antennas radiation characteristics and their tuning by the use of an external magnetic field. They present a wideband antenna profile. The composite resonators studied in this work can be important to the development of a third generation (3G) wideband antennas to cell phones and other wireless products. Due to a fast progress in the development of communication systems, the dielectric and magnetic ceramics (ferrites) have become attractive to be used in devices. Although the ferrites of the spinel type were the first material used in the microwave range, garnets have smaller dielectric losses and, therefore, are chosen for many applications. High demands for modern electric applications in magnetic materials results in new techniques and products being permanently studied and researched, with a consequent appearance of new solutions for a wide applications series. In this sense, the research in composites is employed to reach new materials. This work presents the study of the ferrimagnetic composite, constituted by Y3Fe5O12 (YIG) and Gd3Fe5O12 (GdIG) phases, through solid state synthetic route and submitted to high-energy mechanical milling. The X-Ray Diffraction and the Raman, Infrared and Mössbauer Spectroscopy were essential for the structural characterization of the composites. The peculiarities in the morphology of the samples were elucidated by Scanning Electron Microscopy and Vickers Microhardness. Additionally, experiments were made in order to evaluate the electric and magnetic behavior of the composites at radio frequency and microwave range and then later suggest an adequate technological application. The composites were efficient as ferrite resonator antennas (FRAs) and microstrip antennas (thick films deposited on metalized surface alumina substrate by screenprinting technique), in the microwave frequency range. The experiments with FRAs showed satisfactory due to the control of the antennas radiation characteristics and their tuning by the use of an external magnetic field. They present a wideband antenna profile. The composite resonators studied in this work can be important to the development of a third generation (3G) wideband antennas to cell phones and other wireless products.
This document abstract is also available in Portuguese.
Bibliographical Information:

Advisor:Antonio Sergio Bezerra Sombra; Adrião Duarte Dória Neto; Claudio Lenz Cesar; Lindomar Roberto Damasceno da Silva; Luiz Constantino Grombone Vasconcellos

School:Universidade Federal do Ceará

School Location:Brazil

Source Type:Master's Thesis

Keywords:Ferritas Ferrits, magnetic ceramics, resonator antennas, materials characterizations. materialscharacterizations.

ISBN:

Date of Publication:04/25/2008

© 2009 OpenThesis.org. All Rights Reserved.