Estudo de filmes finos nanocompósitos de titanato de bário/ferrita de cobalto produzidos pelo processo sol-gel

• Ano de defesa: 2012
• Autor(a) principal: Helen Rose de Castro Silva Andrade
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Minas Gerais; UFMG
• Palavras-chave em Português: titanato de bário; elipsometria espectroscópica; filme fino multiferróico ferroelétrico-ferrimagnético; dip-coating; tratamento térmico; nanoindentação; Filmes finos; nanocompósitos; Físico química; Processo Sol-Gel; Propriedades magneticas
• Link de acesso: http://hdl.handle.net/1843/SFSA-A8PRB5

In this work, a study of the physical-chemistry properties of materials consisting of BaTiO3, CoFe2O4 and intercalated BaTiO3/CoFe2O4 thin films produced by sol-gel process, using dip-coating technique, was realized. The barium titanate shows ferroelectric propertywhile cobalt ferrite has magnetic characteristic, providing conditions for a magneto-electric coupling in the nanocomposite BaTiO3/CoFe2O4.BaTiO3 thin films were prepared from an alcoholic solution containing titanium isopropoxide (IV) and barium acetate, and CoFe2O4 thin films were prepared from an alcoholic solution containing iron (III)-acetyl-acetonate and cobalt (II) nitrate hexahydrate.The intercalated nanocomposite BaTiO3/CoFe2O4 thin films were prepared using the same alcoholic solutions described previously.The employed heat treatments have generated structural, morphological and textural changes in these films, whose structure are dependent on factors such as the type of substrate, heating temperature, time of temperature exposure and cooling method. These changes were studied using high-resolution microscopy techniques that providedinformation about the crystallinity, size and shape of the BaTiO3 and CoFe2O4 nanoparticles that form the thin films. Nanoindentation technique has provided important mechanical information of theBaTiO3 thin films as the Young's modulus and hardness, and these values varied with the temperature of thermal treatment. The Spectroscopic Ellipsometry technique was useful in the evaluation of optical properties of these films, such as refractive index, extinctioncoefficient, optical thickness and roughness. The morphological, structural and textural evaluation of the obtained thin films alloweda broad assessment of the characteristics of these films, and therefore, a statement of which of them can be a good multiferroic ferroelectric-ferrimagnetic thin film.