0-3 piezocomposites with anisometric single-crystalline filler particles crystallographically oriented by dielectrophoretic alignment method

Abstract

This study investigates the synthesis, structural characterization, and dielectrophoretic alignment of potassium strontium niobate-KSN (KSr2Nb5O15) particles to develop textured 0-3 piezocomposites with enhanced dielectric and piezoelectric properties for tactile sensor applications. KSN particles were synthesized using a molten salt process. Anisometric needle-like morphology of the particles were confirmed by electron microscopy and their single crystalline nature by electron diffraction techniques. Dielectrophoretic alignment under an alternating current (AC) electric field facilitated particle orientation along the [001] c-axis of the tetragonal structure, as confirmed by x-ray diffraction and quantified using the Lotgering factor (f(00l)). An f(00l) = 0.83 was achieved for piezocomposite containing 5 vol% KSN particles and cured under an AC field of 2 kV mm-1 at 200 Hz. Electrical characterization revealed a strong correlation between particle alignment and properties. Compared to random piezocomposites prepared without AC field, increase in dielectric constant of up to two-folds, in polarization of up to ten folds, and in piezoelectric charge coefficient of up to 3 folds were observed in textured piezocomposites. A tactile sensor prototype developed using these textured piezocomposites exhibited voltage output proportional to particle orientation, demonstrating the importance of particle alignment in enhancing the functional properties of piezocomposites.