The impact of microstructure in (K,Na)NbO3-based lead-Free piezoelectric fibers: From processing to device production for structural health monitoring

The development of (K,Na)NbO3-based ceramics is attracting great interest due to growing environmental concerns. We investigated the effect of sintering dwell times on the microstructure and on the electromechanical properties on (K,Na)NbO3-based ceramic fibres. The results show that microstructural control is the impetus for the development of the improved electromechanical properties as it was found that a shorter sintering dwell time improved the small signal properties while a longer dwell profile improved the large signal properties. Varying the sintering dwell time resulted in the formation of a secondary phase which displaces the alkaline elements, from the main perovskite phase, generating the stabilization of the orthorhombic phase at room temperature. The microstructure has a close relationship to the electromechanical response, that is, a uniform and fine grain microstructure is required for high mechanical strength. A prototype sensor for applications like structural health monitoring, that produces a detectable electromechanical response was produced.