Ferrimagnetic Phase
Mostrando 1-11 de 11 artigos, teses e dissertações.
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1. Ferrimagnetic to paramagnetic transition and dielectric relaxation in Ni1-xZnxFe2O4 ferrites
Abstract The spinel ferrite system Ni1-xZnxFe2O4 (x=0-0.7, Δx=0.1) was prepared by wet chemical co-precipitation method using sulfates of respective metal ions. The electrical resistivity and dielectric properties of the prepared samples have been studied as a function of temperature, frequency, and Zn content (x). The DC resistivity (ϱ) was measured in th
Cerâmica. Publicado em: 2021-06
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2. Synthesis and Characterization of Hybrid Ni0.5Zn0.5Fe2O4@SiO2/chitosan
In this work we evaluate the use of silane agent 3-aminopropyltrimethoxysilane and biopolymer chitosan to functionalize ferrites Ni0.5Zn0.5Fe2O4 using the solvent evaporation method aiming at obtaining hybrid material Ni0.5Zn0.5Fe2O4@SiO2/chitosan for use as a biosensor. The nanoparticles before and after the functionalization showed the major phase Ni0.5Zn0
Mat. Res.. Publicado em: 24/08/2017
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3. Characterization and Chemical Stability of Hydrophilic and Hydrophobic Magnetic Nanoparticles
Magnetic nanoparticles can improve the efficiency of phase separation time in multi-stage operations when a magnetic field is present. As such operations involve contact with aqueous and/or organic solutions, hydrophilic magnetic nanoparticles synthesized through the co-precipitation method were functionalized with oleic acid to attain hydrophobic magnetic n
Mat. Res.. Publicado em: 10/04/2017
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4. Thermal Transformation and Characterization of Synthetic Al-Substituted Maghemites (γ-Fe2-xAlxO3)
ABSTRACT Burning is a common practice in tropical areas and related changes in mineralogy might affect the chemical and physical behavior of soils. Maghemite is a common iron oxide in soils formed from basic rocks in tropical regions. This mineral and hematite are the main pigments in these soils and exhibit high magnetization stemming from the precursor mag
Rev. Bras. Ciênc. Solo. Publicado em: 03/11/2016
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5. Otimização da síntese de nanoferritas de nizn dopada com cobre e cobalto
Foram sintetizadas diferentes composições da ferrita Ni0-5-xCuxZn0,5Fe2O4 e Ni0,5- xCoxZn0,5Fe2O4 com 0 ≤ x ≤ 0,3 pelo método dos citratos precursores. As composições estequiométricas foram calcinadas em atmosfera ambiente na temperatura de 350C e depois prensadas em pastilhas e toróides. As amostras prensadas foram sinterizadas nas temper
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia. Publicado em: 01/08/2011
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6. Investigation of structural, electronic and magnetica properties of Ca2-xLaxFelrO6, Sr2-xLaxFelrO6 e TbMnO3 oxides / Investigação as propriedades estruturais, eletronicas e magneticas dos oxidos Ca2-xLaxFelrO6, Sr2-xLaxFelrO6 e TbMnO3
For many decades the transition metal oxides are subject of great scientific interest because of the wide variety of interesting physical properties and their potential technological applications. More recently, for example, oxides of transition metals with multiferroic properties have been considered as potential magneto-electronic devices. Many transition
Publicado em: 2010
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7. Estado fundamental do modelo de Hubbard estendido na cadeia AB2
In this dissertation we study the extended Hubbard model in the AB2 chain. The model hamiltonian contains a kinetic term, parameterized by t, and two terms of coulomb repulsion,U (intra-site) and V (inter-site). Considering a peculiar local exchange symmetry of the chain, as well as global symmetries of the Hubbard hamiltonian, we have applied the numerical
Publicado em: 2008
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8. On the synthesis and magnetocaloric effect of Fe2P, Mn2Sb and MnAs based compounds / Da sintese e do efeito magnetocalorico de compostos derivados do Fe2P, Mn2Sb e MnAs
On this PhD thesis some results on the magnetic, magnetocaloric and structural properties of some series of compounds suitable for applications on magnetocaloric effect-based refrigeration are presented. The FeMnP1-xAsx series preparation methods are studied in order to optimize their magnetocaloric properties as well as to shorten its preparation time. A ne
Publicado em: 2008
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9. A study on the influence of titanium and cobalt ions in the magnetic and electromagnetic absorption properties of barium hexaferrite / Estudo da influência de íons titânio e cobalto nas propriedades magnéticas e absorvedoras de ondas eletromagnéticas de hexaferrita de bário / Estudo da influência de íons titânio e cobalto nas propriedades magnéticas e absorvedoras de ondas eletromagnéticas de hexaferrita de bário / A study on the influence of titanium and cobalt ions in the magnetic and electromagnetic absorption properties of barium hexaferrite
In this work Cobalt and Titanium doped Barium hexaferrites were synthesized by the ceramic method in order to study their use as electromagnetic absorbing materials in high frequencies. The dopants were used individually (Ti and Co) and with both simultaneously (CT). Ceramic characteristics and magnetic properties of calcined powders, as well as of their pel
Publicado em: 2008
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10. Phase diagrams of the Blume-Emery-Griffiths thin films
We study the spin-1 Blume-Emery-Griffiths model with bilinear and biquadratic exchange interactions and single-ion crystal field, using the mean field theory. In addition to the four usual phases: The disordered phase D, the ferromagnetic phase F, the staggered quadrupolar phase SQ and The ferrimagnetic phase I, we found two new phases, in the case of a thin
Brazilian Journal of Physics. Publicado em: 2006-06
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11. Uso de metodo sol-gel e de coprecipitação na preparação de oxidos metalicos
This thesis describes the preparation of two crystalline solids obtained by thermal decomposition of poorly crystallized solids obtained by precipitation techniques. Magnetite a ferrimagnetic crystalline solid, was obtained by heating non-crystalline iron (III) hidroxoacetate (HAFe), under nitrogen. Mixed oxides of La-Ba-Cu and Y-Ba-Cu, which are superconduc
Publicado em: 1992