Structural and electrical properties of La-Sr-Mn-O ceramics with Bi3+ content for thermistor devices

Abstract

La0.7Sr0.3-xBixMnO3 (LSBMO) (0.025 ≤ x ≤ 0.15) films are fabricated by a sol-gel method and spin-coating method. All of thefabricated films have typical polycrystalline perovskite structures. In addition, no preferential orientation or impurity couldbe observed. The surface SEM images show almost homogeneous and uniform microstructures and the average thickness forthe LSBMO films is approximately 230 to 260 nm. When the resistivity is measured at room temperature, the TCR andB85/25-values gradually increases as the amount of Bi3+ increased, and the highest values of 0.023 mΩ·cm, 0.31%/°C and 299K are obtained in the La0.7Sr0.225Bi0.075MnO3 thin films. Polycrystalline LSBMO films follow the variable-range hopping (VRH)conduction model as they show electron-electron scattering and electron-phonon interactions for thermal stimulation.