Nonlinear electrical behaviors and conductivity mechanisms in Ca1-xYbxCeNbWO8 ceramics

In this study, we investigated the nonlinear electrical behaviors and conductivity mechanisms of Ca_1-xYb_xCeNbWO₈ 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 Ca_1-xYb_xCeNbWO₈ 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.