Conclusion
In this work, all ceramic samples were produced by solid-state reaction method. The optimum
sintering temperature for prepare the KNN-N, KNN-LS and KNN-LST12 ceramics
is 1130◦C for 4 h. The crystal structure of ceramic samples was perovskite structure with
different symmetry. KNN-N samples only represent orthorhombic phase while KNN-LS
and KNN-LST12 ceramics represent the mixture of orthorhombic and tetragonal phase.
The density of all ceramics increases with increasing sintering temperature and Ta content.
The KNN-LST12 was found to be the best of all samples due to it showed maximum piezoelectric
constant d33 (∼192 pC/N) and dielectric constant (∼1019) with low dielectric
loss (∼0.038). This result indicates that the optimum sintering temperature and Ta addition
develops the dielectric and piezoelectric properties of KNN-based ceramics.