effect of nio sintering aid on the electrical properties of knn-lst lead-free piezoceramics

The current research focuses on the synthesis and characterization of sodium potassium niobate (knn), a lead-free piezoelectric compound. the objective is to replace lead-based compounds like pzt using knn-lst, which is sodium potassium niobate piezoceramic powder doped with lithium, antimony, and tantalum. to this end, solid-state method was employed to sinter the samples at 1110 °c with varying percentages of nio sinter aid (0%, 0.75%, 1.5%, and 2.25%). x-ray diffraction analysis confirmed the formation of pure knn-lst perovskite phase at 1110 °c with a composition containing 1.5% nio. scanning electron microscope images also demonstrated that cubic particles inherent in knn were observed in samples with no nio addition as well as those containing 0.75% and 1.5% nio; however, these particles were transformed into cylindrical grains when incorporating 2.25% nio. with an increase in the sintering percentage from zero nio content to higher amounts, sample density also increases from approximately 85% up to its peak at around 94%, followed by a slight decrease by about 91%. similarly, the dielectric coefficient increased from approximately850 without any contribution from nio sinter addition up to1500 upon addition of 1.5%nio sinter but then, it decreased again by approximately 1200 followed by addition of 2.25% nio sinter. conversely, dielectric loss initially reduced from roughly 0.14% during no nio sinter addition by merely 0.04% during 1.