IMF2017

The SnO₂ is an intrinsic n-type semiconductor that at ambient pressure commonly crystallizes as cassiterite, which has the rutile structure with tetragonal symmetry (space group P42 / mnm). Another polymorph of SnO₂ is with the orthorhombic structure which is a metastable phase originally obtained in experiments with high pressures and temperature. In this work, we have investigated the formation of the orthorhombic phase of α-PbO₂-type SnO₂ in the nanoparticle system x = 0, 0.05, 0.1 and 0.3 synthesized at 750 °C in an air atmospheric by the Pechini’s method. We studied the formation of the α-PbO₂-type phase as a function of the synthesis temperature and Cerium concentrations. The structural and morphological characterization was performed using experimental techniques such as X-ray diffraction (XRD), allied to the Rietveld refinement, field emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM). The reflections in the XRD pattern and clear lattice fringes observed by HRTEM confirm the formation of the orthorhombic SnO₂ phase. Through the Rietveld refinement analyzes it can be observed that the sample with 0.3 moles of cerium reaches a significant mass fraction of the orthorhombic phase, approximately 36%. The reducing atmosphere generated by the heat treatment process of the samples and the strain originated due to the difference of ionic rays between the tin and cerium ion can play a crucial role in the formation of α-PbO2-type SnO₂.