Identification of Chemical Short-Range Order, Structure Evolution, and Origin of Nonlinear Electrical Properties in 0.4La0.9Ca0.1CrO3-0.6MgAl2O4 Composite Ceramics

LaCrO3-based perovskite oxides have garnered substantial attention in advanced electronic devices because of their highly tunable structure as well as their considerable stability. However, the atomic-scale characterization and nonlinear electrical properties in the chromium-based perovskite composites are still far from being fully understood. Here, we firstly reported the chemical short-range orderings (CSROs) as well as the structure evolution and origin of nonlinear electrical properties in 0.4La0.9Ca0.1CrO3−0.6MgAl2O4 composite ceramics. It is found that the CSROs are formed within its cation sublattice of the MgAl2O4 phase involving Mg/Al elements separated by the Cr atom, confirming the interchange of Cr3+ and Al3+ in these two phases. In the wide temperature range of −50 °C∼1000 °C, the ln ρ versus 1/T relation of the composites transforms around 600 °C, which may be due to the phase transition and the decline of CSROs. The values of Ea-50/600◦C and Ea600/1000◦C are 0.207 eV and 0.046 eV, respectively. Tanδ shows an exponential increase above 600 °C, suggesting a phase transition in around 600 °C. Based on complex impedance analysis, we further explore and verify the structural evolution and reason for the electrical performance anomaly. These outcomes indicate that the structure can be modulated by composite design, opening a route to tailor the properties of LaCrO3-based materials.