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Browsing by Author "Villada Gil, Stiven"

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    Síntesis de la espinela ZnCrxFe2-xO4(0 ≤ x ≤ 1) por combustión en solución y estudio termodinámico de la estabilidad de fases
    (Corporación Universitaria Lasallista, Editorial Lasallista., 2018) Montoya Carvajal, Juan Fernando; Chavarriaga Miranda, Andrés; Villada Gil, Stiven
    Introduction. Spinels are metal oxides generally used for their chemical, electrical and magnetic properties. The occupation of transition metals in tetrahedral and octahedral positions generates characteristics of technological interest and the study of the interaction of the material with external fields is motivating and justifiable. The synthesis of spinels has commonly been using the traditional method (ceramic), but to obtain better control in the particle size alternative methods have been chosen, among them the method of combustion in solution. Objective. Synthesize the spinel by the combustion method in solution and study the phase transitions as a function of temperature. Materials and methods. The compound was synthesized (for x = 0, 0.2, 0.4, 0.6, 0.8, 1.0) by combustion in solution, using metallic nitrates and glycine as fuel, generating an ignition around 1500 ° C approximately. Results The samples were characterized morphologically (SEM), compositionally (EDS), structurally (XRD), thermogravimetrically (TGA) and calorimetrically (DSC). The characterization was carried out for precalcined samples (without thermal treatment), heated to 750 and 850 ° C, this in order to compare the results obtained in the characterizations of the compounds and thereby identify the physical changes generated by the formation of secondary phases .
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    Síntesis y caracterización de la Espinela FeCr2O4
    (Corporación Universitaria Lasallista, 2015-08-03) Montoya Carvajal, Juan Fernando; Chavarriaga Miranda, Edgar Andrés; Villada Gil, Stiven; Muñoz García, Andrés Mauricio; Restrepo Baena, Óscar Jaime
    Introduction. Compounds with spinel structures are known for having cations in their tetrahedral and octahedral structures, a fact that gives them versatility for technological applications given their physical and chemical properties (Ziemniak, Anovitz, Castelli y Porter, 2007, 1474–1492). Ferrites and chromites are especially interesting due to their diverse physical properties and their consequent versatility for technological applications (Gopal y Spaldin, 2006, 094418-9; Singh y Rhee, 2010, 1233-1237). Objective. Synthetize, with the traditional ceramic method, the FeCr2O4 spinel and identify its main properties taking its structural, colorimetric and magnetic characterization as a base. Materials and Methods. By the use of reactions in the solid state at high temperatures, by means of the iron and chromium oxides (Cr2O3 and Fe3O4) at fixed proportions as precursors, the FeCr2O4 compound with a spinel type structure was synthetized. For the synthesis of different temperatures, a characterization of the material obtained was performed by means of X ray diffraction (DRX), UV-VIS-NIR spectroscopy, thermal analysis (DTA/TGA) and the magnetic susceptibility. Results. The results obtained agree with the reports and it can be seen that the changes in the reflectance spectrums are correlated with the base identified, with the crystallinity degree and with the magnetic response. Conclusions. The FeCr2O4 spinel was satisfactorily synthetized by the use of the traditional method for temperatures between 800 and 1300 °C, and samples with structural and optically stability were obtained.