High Piezoelectric Voltage Coefficient in Structured Lead-Free (K,Na,Li)NbO₃ Particulate—Epoxy Composites

Abstract

A high-voltage coefficient has been found in lead-free piezoelectric particulate composites based on epoxy with lead-free (K_0.50Na_0.50)_0.94Li_0.06NbO₃ (KNLN) piezoceramic particles with a natural cubic morphology. The KNLN powder used in the composites has been prepared using a new solid-state double calcination processing route. These particles were subsequently used to create random and structured KNLN-epoxy composites. Using dielectrophoresis, these natural cubical KNLN particles were structured into one-dimensional chains inside the epoxy matrix. Composites produced with these powders showed piezoelectric properties about a factor of 2 higher than those of composites processed with conventionally calcined KNLN powders. The dielectrophoretically structured KNLN-epoxy composites with optimized particle size and morphology showed excellent piezoelectric properties, which can replace lead containing piezoelectric composites for sensor and energy harvesting applications in future.