Spinel
Mostrando 1-12 de 86 artigos, teses e dissertações.
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1. Influence of the Local Structure on the Photocatalytic Properties of Zinc Spinel Ferrite Nanoparticles
The correlation between iron distribution in octahedral or tetrahedral sites in synthetic magnetite and zinc spinel ferrites and their catalytic properties were investigated in this work. The zinc-doped nanomagnetites were prepared by co-precipitation method and annealed at 420 °C. X-ray diffraction, UV-Vis, X-ray absorption and 57Fe Mössbauer spectroscopi
Journal of the Brazilian Chemical Society. Publicado em: 2022
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2. Biphasic 0.8BaTiO3/0.2Ni(1-x)CoxFe2O4 nanopowders by in situ sol-gel synthesis
Abstract Nanopowders of the 0.8BaTiO3/0.2Ni(1-x)CoxFe2O4 (x=0, 0.25, 0.5, 0.75, and 1) were synthesized by the in situ sol-gel method using poly(acrylic acid) (PAA1800) as a chelating agent. The synthesis developed using PAA1800 ensured the simultaneous crystallization of two phases. The results provided a reliable method for producing biphasic nanopowders i
Cerâmica. Publicado em: 2022
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3. Iron Cobaltite (FeCo2O4) Nanocatalysts for Water-Oxidation: Effects of Annealing Temperature on Catalytic Properties
The development of efficient, stable, and non-precious metal water oxidation catalysts (WOCs) is a matter of importance for sustainable energy research. In this work, iron cobaltite (FeCo2O4) nanoparticles were prepared by the coprecipitation method, and we present the effect of heat treatment (250, 350, 450, 650 and 900 °C) on the catalytic properties. Cat
Journal of the Brazilian Chemical Society. Publicado em: 2022
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4. 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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5. Experimental and Theoretical Study of LiMn2O4 Synthesized by the Solution Combustion Method Using Corn Starch as Fuel
Lithium manganese oxide, LiMn2O4, was synthesized in two temperature stages, where the first consisted by an ecofriendly solution combustion method at 300 °C. Finally, the as-burned powders were thermal treated at 500 and 700 °C. The structural and morphological changes were evaluated by the Rietveld method and density functional theory (DFT) calculations.
J. Braz. Chem. Soc.. Publicado em: 2020-02
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6. Cation Vacancies in NiFe2O4 During Heat Treatments at High Temperatures: Structural, Morphological and Magnetic Characterization
Nickel ferrite (NiFe2O4) was synthesized by mixing stoichiometric amounts of α-Fe2O3 and NiO using mechanical milling and heat treatments at high temperatures. The physical characterization of the samples was carried out using X-ray diffraction, infrared and Raman spectroscopies, Mössbauer spectrometry, magnetization measurements, scanning electron microsc
Mat. Res.. Publicado em: 20/12/2019
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7. Obtenção de ferritas de cálcio dopadas com cromo visando aplicação em esmaltes transparentes brilhante e mate
RESUMO Este trabalho tem como objetivo obter óxidos com estrutura tipo espinélio de composição CaFe1,8Cr0,2O4 pelo método gelatina, visando aplicação em esmaltes transparentes brilhantes e mate. Os pós precursores, resultantes do processo de síntese, foram calcinados a 600 °C e a 800 °C para a obtenção da fase espinélio. Os pós foram caracteri
Matéria (Rio J.). Publicado em: 25/11/2019
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8. Caracterização de termistores automotivos do tipo NTC
RESUMO Os termistores automotivos são eletrocerâmicas com características sensoras alojadas em estojos metálicos fixadas no radiador, que têm como função controlar a temperatura da água de resfriamento do motor. O objetivo deste trabalho foi caracterizar dois termistores comerciais aplicados em veículos automotores. Os termistores caracterizados for
Matéria (Rio J.). Publicado em: 25/11/2019
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9. Nanoparticles of Ni1-x Znx Fe2 O4 used as Microwave Absorbers in the X-band
Ferrites nanoparticles of Ni1-xZnxFe2O4 ferrites with x varying between 0 and 1, in steps of 0.2, were obtained by solution combustion synthesis (SCS) and dispersed in oil paint at the concentrations of 10, 20, 30 and 40% by ferrite weight of ferrite, with the aim of producing electromagnetic wave absorbing composites, in the X band (8-12 GHz). The ferrite p
Mat. Res.. Publicado em: 21/10/2019
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10. Síntese e caracterização de cobaltita de níquel (NiCo2O4) obtida pelométodo dos precursorespoliméricos
RESUMO A cobaltita de níquel (NiCo2O4) de estrutura do tipo espinélio apresenta baixa estabilidade térmica em torno dos 400 °C, que ocasiona a perda de NiO, afetando de maneira significativa as propriedades físicas e estruturais do material produzido. Neste trabalho a cobaltita de níquel foi preparada pelo método dos precursores poliméricos. O materi
Matéria (Rio J.). Publicado em: 16/09/2019
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11. Study of ZnAl2O4 spinel nanoparticles synthesized using gelatin as organic precursor
Resumo Neste trabalho, pós do espinélio aluminato de zinco foram preparados por um método Pechini modificado, rápido, simples, ambientamento seguro e de baixo custo, utilizando gelatina comercial como precursor orgânico. Os materiais foram calcinados a 600, 700 e 800 °C e caracterizados por análise termogravimétrica, difratometria de raios X (DRX) in
Cerâmica. Publicado em: 06/06/2019
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12. Thermal behavior (TG-DTA-TMA), sintering and properties of a kaolinitic clay from Buenos Aires Province, Argentina
Resumo As propriedades tecnológicas de um caulim local, considerado um potencial material industrial, foram correlacionadas com o comportamento térmico e processos de sinterização realizados por meio de uma série de análises termoquímicas. A caracterização química e mineralógica do material foi realizada, juntamente com uma simples caracterizaçã
Cerâmica. Publicado em: 06/06/2019