Optimizing the defect chemistry of Na1/2Bi1/2TiO3-based materials: Paving the way for excellent high temperature capacitors
Abstract
In applications for the automotive, aviation and renewable energy industry the temperature and power requirements have increased significantly for electronic components. Especially capacitors have been identified as the most critical part considering the fulfillment of these requirements. Ceramics are the most promising materials for high temperature capacitors but no ceramic was able to meet the necessary electrical properties so far. In this work, Na1/2Bi1/2TiO3 (NBT) solid solutions are investigated investigated to optimize the respective electrical properties. A reduction of bismuth vacancy and oxygen vacancy concentration by increasing the initial Bi content leads to a significant decrease in dielectric loss. Additionally, energy efficiencies of up to 97% can be achieved for the composition Na1/2Bi1/2O3-BaTiO3-CaZrO3 (NBT-BT-CZ) and the temperature range of stable high permittivity together with low dielectric loss (tanδ≤0.02) extends from -67 °C to 362 °C. Hence, the optimization of the defect chemistry of NBT-materials results in highly stable electrical properties over a large temperature and electric field range, which lead to the fulfillment of industrial requirements.