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Master's Dissertation
DOI
10.11606/D.43.2013.tde-26112014-135553
Document
Author
Full name
Valquiria Fernanda Gonçalves de Lima
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
São Paulo, 2013
Supervisor
Committee
Santos, Antonio Domingues dos (President)
Bakuzis, Andris Figueiroa
Nagamine, Luiz Carlos Camargo Miranda
Title in Portuguese
Preparação e caracterização de nanopartículas magnéticas de Sm-Co, Nd-Fe-B, Fe-Pt e Co-Pt pelo método de agregação gasosa
Keywords in Portuguese
Magnetismo
Nano-imãs
Nanopartículas
Sputtering
Abstract in Portuguese
Atualmente, nanopartículas (NPs) são utilizadas em todos os ramos da tecnologia. Suas promissoras aplicações envolvem entre outros, o campo dos sensores e transdutores, mídia de gravação magnética, carreadores magnéticos de drogas medicinais. Com o objetivo de produzir NPs pelo método físico, um gerador de nanopartículas foi adaptado usando um dos canhões do sistema de magnetron sputtering, baseando-se no método de agregação gasosa. Com o gerador somos capazes de produzir NPs de diversos materiais e codepositá-las em matrizes dielétricas ou metálicas. Neste trabalho apresentamos o desenvolvimento da metodologia para a produção de nanopartículas de materiais magnéticos duros, usando alvos de SmCo5, Sm2Co17, Nd2Fe17B, FePt e CoPt. Investigamos a influência dos parâmetros de deposição (pressão, fluxo de gás e potência de sputtering), tipo de substrato e a existência de buffer e/ou codeposição, na obtenção das propriedades estruturais e magnéticas desejadas para esses materiais. As NPs produzidas são analisadas magneticamente pelo VSM e SQUID, sua morfologia e tamanho por TEM e SEM, a sua estequiometria pelo RBS, e a sua estrutura cristalina por XRD, a fim de obter nano-ímãs de alta anisotropia magnética. Da caracterização morfológica, através de microscopia eletrônica, encontramos para as NPs produzidas e estudadas diâmetros entre 5 e 17 nm. Através de análises de RBS obtemos para composição das NPs que as mesmas possuem estequiometria diferente dos alvos usados. Estudos estruturais e magnéticos mostram que para Sm-Co, Fe-Pt e Co-Pt é possível obter NPs cristalinas e com coercividade da ordem de 1 kOe.
Title in English
Production and characterization of nanoparticles of high magnetic anisotropy of Sm-Co, Nd-Fe-B, Fe-Pt e Co-Pt using the gas aggregation method
Keywords in English
magnetism
nano-magnets
Nanoparticle
sputtering
Abstract in English
In the recent years, nanoparticles (NPs) are being in all fields of technology. Their promising applications involve among others, the field of sensors and transducers, magnetic recording media, magnetic carriers of medicinal drugs. Aiming to produce NPs by physical method, a generator of nanoparticles was adapted using a system of guns "magnetron sputtering", based on the aggregation gas method. With the generator we are able to produce NPs with different types of material. In this work, we present the development of the methodology for the production of nanoparticles of hard magnetic materials, using targets of SmCo5, Sm2Co17, Nd2Fe17B, FePt and CoPt. We investigated the influence of the deposition parameters (pressure, gas flux and sputtering power), substrate type and the existence of the buffer and/or codeposition layers, to obtain the desired structural and magnetic properties for the nanoparticles. The produced NPs were magnetically analyzed by VSM and SQUID, the morphology and size by TEM and SEM, the stoichiometry by RBS and the crystal structure by XRD. The main objective of this work is to obtain nano-magnet with high magnetic anisotropy. Through the morphological characterization by electron microscopy, we found for NPs produced and studied have diameters between 5 and 17 nm. Through RBS analysis we have obtained the composition of the NPs, and also that they have different stoichiometry in relation to the used targets. Structural and magnetic studies have show that for Sm-Co, Fe-Pt and Co-Pt it is possible to obtain crystalline NPs with coercive field around 1 kOe.
 
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Publishing Date
2014-11-27
 
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