Grain size effect on the universality of AC conductivity in SnO2 Original Research Article

Nanocrystalline tin oxide (SnO2) material with different grain sizes was synthesized by using a chemical precipitation method. This material was characterized by using the X-ray diffraction and transmission electron microscopy. The electrical properties of compressed nanocrystalline SnO2 were studied by using impedance spectroscopy. AC conductivity data for SnO2 material having grain sizes between 9 and 34 nm were analyzed using a power law. The exponent n is found to be 0.5 for bulk (34 nm) and unity for material with grain size below 18 nm. The results show a universal behavior for very low average grain sizes and the non-universal behavior for larger grain sizes even at room temperature.