masterThesis
Obtenção e caracterização de dióxido de estanho nanoestruturado pelo método de síntese contínua por combustão em solução
Fecha
2012-02-07Registro en:
ARAUJO, Micheline dos Reis. Obtenção e caracterização de dióxido de estanho nanoestruturado pelo método de síntese contínua por combustão em solução. 2012. 105 f. Dissertação (Mestrado em Processamento de Materiais a partir do Pó; Polímeros e Compósitos; Processamento de Materiais a part) - Universidade Federal do Rio Grande do Norte, Natal, 2012.
Autor
Araujo, Micheline dos Reis
Resumen
Continuous Synthesis by Solution Combustion was employed in this work aiming to
obtain tin dioxide nanostructured. Basically, a precursor solution is prepared and
then be atomized and sprayed into the flame, where its combustion occurs, leading
to the formation of particles. This is a recent technique that shows an enormous
potential in oxides deposition, mainly by the low cost of equipment and precursors
employed. The tin dioxide (SnO2) nanostructured has been widely used in various
applications, especially as gas sensors and varistors. In the case of sensors based
on semiconducting ceramics, where surface reactions are responsible for the
detection of gases, the importance of surface area and particle size is even greater.
The preference for a nanostructured material is based on its significant increase in
surface area compared to conventional microcrystalline powders and small particle
size, which may benefit certain properties such as high electrical conductivity, high
thermal stability, mechanical and chemical. In this work, were employed as precursor
solution tin chloride dehydrate diluted in anhydrous ethyl alcohol. Were utilized molar
ratio chloride/solvent of 0,75 with the purpose of investigate its influence in the
microstructure of produced powder. The solution precursor flux was 3 mL/min.
Analysis with X-ray diffraction appointed that a solution precursor with molar ratio
chloride/solvent of 0,75 leads to crystalline powder with single phase and all peaks
are attributed to phase SnO2. Parameters as distance from the flame with atomizer
distance from the capture system with the pilot, molar ratio and solution flux doesn t
affect the presence of tin dioxide in the produced powder. In the characterization of
the obtained powder techniques were used as thermogravimetric (TGA) and
thermodiferential analysis (DTA), particle size by laser diffraction (GDL),
crystallographic analysis by X-ray diffraction (XRD), morphology by scanning electron
microscopy (SEM), transmission electron microscopy (TEM), specific surface area
(BET) and electrical conductivity analysis. The techniques used revealed that the
SnO2 exhibits behavior of a semiconductor material, and a potentially promising
material for application as varistor and sensor systems for gas