Stress-induced tailoring of phase boundaries and energy storage properties in lead-free antiferroelectric AgNbO3

• Applicant: Neamul Hayet Khansur, Ph.D.
• Subject Area: Synthesis and Properties of Functional Materials
• Term: since 2020
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 447864104

Electrical energy storage plays a crucial role in the realization of sustainable energy by enabling the more efficient use of energy generated from renewable sources as well as in modern electronics. In recent years, there has been an effort to develop environmentally friendly, i.e., lead-free, new energy storage materials with a superior integrated performance that enables high energy and high power densities to support emerging applications. Electrochemical devices and dielectric devices are the two candidates at the forefront of energy storage technology. Among them, dielectric ceramic capacitors have the advantages of fast charge-discharge time (>1µs) and high power density (W/cm3), and are promising candidates for energy storage devices, especially for pulse power (PP) and power electronics applications, where high voltage and maximum potential energy density (J/cm3) are desirable. In this regard, non-linear dielectric ceramic materials, e.g., antiferroelectric (AFE) materials, are attractive for such applications. Unfortunately, most high performance antiferroelectric ceramic capacitors are lead-based. Recent work has shown high energy density in AgNbO3 bulk ceramics that is comparable to the lead-based bulk antiferroelectric ceramics. However, the full potential of energy storage performance in AgNbO3 has not yet been realized primarily due to the challenges in the synthesis of phase pure and dense AgNbO3 ceramic films. In addition, the effect of mechanical stress on the temperature-dependent phase boundaries in bulk, as well as thick film AgNbO3, has not yet been investigated. An understanding of this external field-induced phase transformation is crucial to implement these materials into applications and improve the working temperature range of AFE-based capacitors. The aim of this project is the investigation of stress-induced tailoring of phase boundaries and energy storage properties in AgNbO3.

• DFG Programme: Research Grants