Síntese e caracterização de ligas metálicas nanométricas FeNi pelo método sol-gel proteico

Abstract

In recent decades, nanoscience has led science to revolutionize the field of materials. The superparamagnetic properties of nanocrystals are being widely studied due to their applications in medical and biological areas, which are used in cancer treatment, and are important vectors cell transport, proteins and drugs. The work aims at the synthesis and determination of the nanocrystal properties of iron-nickel (FeNi), whose most significant application is in industry, where it acts as an important catalyst. The protein sol-gel method is a fast synthesis process and economically viable, which allows to produce materials with nanoscale features currently very desirable in terms of applications. Alloys produced used iron and nickel nitrates, edible gelatin Gelita mark as a precursor agent and hydrogen as a reducing agent. The calcining the xerogel occurred primarily in a tubular furnace coupled with rotation, at 700oC for two hours with an air flow of 30 mL/min to oxidize the sample. And reducing subsequent formation of FeNi alloy, series were carried out varying the temperature (500, 600 and 700oC) and hydrogen flow (25, 30, 40 and 50 mL/min). We observed the formation of pure alloy thermal all series at 700oC and for streams 40 and 50 mL/min applied to the material reduced at 500 to 600oC. The X-ray diffraction was used to characterize the obtained alloys, identifying the phases present in each sample. The Rietveld structure refinement was applied, determining the structural and microstructural parameters of the samples. The equation of Scherrer and graphical method of Williamson-Hall were used in the calculations of the crystallite size and scanning electron microscopy of the morphological characteristics of the nanocrystals. The vibrating sample magnetometry was used in the study of magnetic properties, where a magnetic field variation applied to the material at room temperature caused magnetic saturation and coercive field. Obtaining the Mo¨ssbauer spectra were of fundamental importance because of the low concentration of spurious phases containing iron element in the alloy that the technique of X-ray diffraction does not detect. The protein Sol-gel method showed significant results for the synthesis of FeNi alloy, which showed nanoscale spherical partially morphology and homogeneous grain size distribution showing the efficiency of this synthetic route to obtain the alloy with significant features for their application.