Structural and frequency-dependent dielectric properties of (SnO₂)_1−x(Fe₂O₃)_x

A series of iron-substituted tin dioxide ceramics with composition Sn_x−1Fe_xO₂ was synthesized using a conventional solid-state method in order to investigate its detailed structural and dielectric properties. Samples formed in the tetragonal structure with grain sizes of around 88–48 nm. Reduction in grain size was found because of the suppression in the grain growth with Fe addition. From FTIR analysis, a broad peak was centered on 650 cm⁻¹ due to Sn–O vibration. Many Raman-active phonon modes observed for as prepared samples. The Fe substitution in SnO₂ essentially changes the position of modes, where all the modes shifted to a lower wave number. For all the samples, frequency-dependent dielectric and AC conductivity measurements collected at room temperature and in the frequency range from 75 kHz to 10 MHz. In this frequency range, large dielectric dispersion was noted. According to our analysis of electrical properties of the samples under study, it is found that the conduction mechanism in these materials is based only on a small polaron.