Síntese, caracterização estrutural e magnética das perovskitas complexas La0.9Tr0.1Fe0.5Mn0.5O3 (Tr = Nd, Eu)

• Autor(a) principal: Santos, Jeferson Marques
• Data de Publicação: 2016
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Repositório Institucional da UFS
• Texto Completo: http://ri.ufs.br/jspui/handle/riufs/10985
• topic: Perovskitas complexas; Método de reação de combustão; Ordenamento ferromagnético; Interação de supertroca; Complex perovskites; Method of combustion reaction; Ferromagnetic ordering; Superexchange interaction; CIENCIAS EXATAS E DA TERRA::FISICA

New complex perovskites are widely researched in Condensed Matter Physics, this fact is due to their functionality’s properties and efficacy in the use of electronic devices. The goal in this work was to synthesize, to characterize structurally and magnetically the compounds La0.9Tr0.1Fe0.5Mn0.5O3 (Tr = Nd, Eu). Structure, chemical composition, morphology and magnetization have been investigated in our laboratory by means of X-ray diffraction (XRD), X-ray fluorescence (XRF), scanning electron microscopy (SEM) and magnetometry (magnetization versus temperature - MxT and magnetization versus magnetic field - MxH). The samples of this work were synthesized by the combustion reaction method using the reagents: lanthanum nitrate, neodymium nitrate, europium nitrate, iron nitrate, manganese chloride and citric acid anhydride as fuel subsequent heat treated at 1300°C for 18 hours in an oxygen-free atmosphere. X-ray diffraction analyzes indicates single-phase compounds with the space group Pbnm. Macerated, the fine powders obtained after calcination were analyzed by the FRX that show good agreement between the nominal and calculated formula. Images obtained by SEM shows that grain formation of micrometric order size, nonhomogeneous morphology and high coalescence. Magnetic measurements of MxT show that the magnetic susceptibility of both compounds indicates ferromagnetic arrangement that extends to room temperature, MxH from 2 to 100 K presents magnetic hysteresis with ferromagnetic coupling corroborating with the results of MxT. The low temperature magnetization of La0.9Eu0.1Fe0.5Mn0.5O3 is greater than of La0.9Nd0.1Fe0.5Mn0.5O3 possibly due to the magnetic moments of the Nd3+ ions located in the centers of dodecahedral structures that are opposite to the moments of the Mn3+ and Fe3+ ions in the centers of octahedral structures.