Nonlinear electrical behaviors and conductivity mechanisms in Ca_1‐xYb_xCeNbWO₈ ceramics

Abstract

In this study, we investigated the nonlinear electrical behaviors and conductivity mechanisms of Ca1‐xYbxCeNbWO8 ceramics, which are prepared by the solid‐state sintering method. CeO2 and CeNbO4 phases occur when the Yb3+ doping amount is greater than 0.1 in the CaCeNbWO8‐based ceramics. With the continuous incorporation of Yb3+, the grain size of the ceramics first decreases and then increases. The Ce3+ concentration in the ceramics decreases with increasing Yb3+ content. In the temperature range of 298.15 to 1073.15K, the relationship between ln ρ and 1000/T shows nonlinear electrical behaviors, which is attributed to the different conductivity mechanisms at high and low temperatures (ρ and T are resistivity and temperature, respectively). In the temperature range of 298.15 to 773.15K, the electrical conduction in Ca1‐xYbxCeNbWO8 ceramics follows the Efros‐Shklovskii variable‐range hopping (ES‐VRH) conduction mechanism, thermal activation conduction (x < 0.2), and two‐dimensional Mott VRH conduction mechanism (x = 0.2). Furthermore, the electrical conduction obeys the thermal activation conduction mechanism in the temperature range of 773.15 to 1073.15K. The activation energy for the electrical conduction is calculated based on the different hopping conduction mechanisms.