Immittance response of the SnO2-Bi2O3 based thick-films

The SnO₂-Bi₂O₃ based thick-film polycrystalline material is fabricated on alumina substrate via screen-printing technique. This material system is evaluated at various temperatures (35 °C≤T≤100 °C) using ac small-signal (immittance) measurements in the frequency range 10 Hz≤f≤10⁶ Hz. The simplistic analytical scenario for the immittance data employed the Cole-Cole empirical equation in conjunction with the estimation of the inspected input parameters. This is an alternate approach compared to the complex nonlinear least squares (CNLS) fitting procedure, and purely based on the appearance of the semicircular relaxation in the complex plane. It is found that the constituting components of the semicircular relaxation in the impedance plane are thermally activated indicating complexity in the grain boundary contributions despite the Debye and non-Debye relaxation responses. The possible degree of uniformity or non-uniformity in the grain boundary activity associated with its capacitance term observed via the Debye or non-Debye semicircular relaxation in the impedance (Z?) plane has been postulated.