Structural, optical properties, impedance spectroscopy studies and electrical conductivity of SnO2 nanoparticles prepared by polyol method

Tin oxide nanoparticles (SnO2) with controlled shapes and sizes were prepared at 160 degrees C by a simple polyol method. The formation of typical rutilE-type was confirmed by X-ray diffraction studies, and it was found to be a tetragonal structure. X-ray diffraction and transmission electron microscopy show the average diameter of SnO2 nanoparticles about 13 nm obtained after calcination at 700 degrees C. Moreover, the calcined sample is composed of an aggregated network of almost spherical nanoparticles. The optical property was investigated using an UV-visible Diffuse Reflectance Spectroscopy, the band gap is found to be 3.4 eV. Electrical properties were performed using impedance spectroscopy technique in the frequency range 6 KHz-1 MHz at various temperatures (523-723 K). The complex impedance diagram at different temperatures showed a single semicircle, implying that the response originated from a single capacitive element corresponding to the grains. Ac and dc conductivities were studied to explore the mechanisms of conduction. In fact, AC conductivity is found to follow Jonsche's s universal power law. As a result, the exponent's' was found to increase with increase in temperature. Further analysis revealed that, the non overlapping small polaron tunneling model mechanism was applicable at the present temperatures.