Nanoparticle characterization of tin oxide synthesized by different methods

Full text: The control gas emissions are becoming most rigorous and there is a growing need for gas sensors with superior performance (1). Solid-state sensors are based on the fundamental principle that some semiconductor metal oxides such as SnO₂ are very reactive on the surface, where adsorbs the gas simply by changing the resistance of the sensor material when the gas disappears, the sensor returns to its original condition, enabling the detection of gaseous species (2). This work presents results of the characterization of commercial SnO₂ powder and obtained by different methods of synthesis with different temperatures of calcination, for making sensors for methane gas generated by the mining of fossil coal. Results obtained by Infrared Spectroscopy (FTIR) showed similar behavior where all samples showed characteristic peaks corresponding connections of the SnO₂. By means of X-ray Diffraction (XRD), it was observed the existence of a preferential orientation in the plane direction (110), where all peaks are consistent with the phases of pure SnO₂ with the crystal structure of cassiterite, an increase crystallite size and crystallinity in samples calcined at higher temperatures was also observed. Images obtained by Scanning Electron Microscopy (FESEM) showed that the SnO₂ is composed of larger clusters consisting of particles with a smaller size. Through Energy Dispersive Spectroscopy (EDX) it can be seen that the percentage by weight Sn and O in the samples are presented around the value indicated for SnO₂. Analysis of Transmission Electron Microscopy (TEM) indicated a SnO₂ synthesis with nanometric structure. The particles have a regular size distribution for each calcination temperature, with larger size and degree of agglomeration for the samples calcined at higher temperatures. [1] S.D. Bakrania, M.S. Wooldridge, Sensors, 9, 6853 (2009). [2] G. F. Fine, et al. Sensors, 10, 5469 (2010). (author)