The synthesis and characterization of alkaline niobate-based ceramic composites containing L-lysine Hydrochloride

Abstract

Some lead-free piezoelectric ceramics are known to have high dielectric and piezoelectric properties but are limited by their brittle nature. A few amino acids have recently been reported to exhibit rather low dielectric and piezoelectric properties but have the advantage of being biocompatible and flexible. It would therefore be interesting to form a composite that will combine the inherent advantage of high dielectric properties from the ceramics and flexibility from the biomolecule. In this research, the properties of lead-free (K0.45Na0.51Li0.04)(Nb0.85Ta0.1Sb0.05)O3 (KNNLST) ceramics and L-lysine hydrochloride (L-LHCl) have been combined to produce dielectric composites. The samples were produced by mixing the constituents from 0 wt.% to 100 wt.%, pelletising and heat-treating them. Bulk density, X-ray diffraction, scanning electron microscopy, and dielectric characterisation were techniques used to determine the density, phases, morphology, and dielectric properties of the produced composites. The results show an increasing bulk density value from 1.2 g/cm3 for L-LHCl to 4.67 g/cm3 for the KNNLST ceramics. The morphology of the composite shows very tiny grains when small amounts of the ceramics were introduced. The L-LHCl transforms from an amorphous phase to a crystalline phase having the orthorhombic-tetragonal structure with the introduction of the KNNLST ceramics. The dielectric constant values increased with increasing KNNLST ceramics content from 10 @1 kHz to 200 for the composite with 80 wt%. KNNLST content. The dielectric loss values decreased for L-LHCl from 0.9 @1 kHz to 0.2 @1kHz. The electrical conductivity values increased with increasing KNNLST ceramics content. The results show that the composites produced from these constituents may be suitable for dielectric applications.