Electrical Properties and Impedance Spectroscopy of Lithium Modified Potassium Sodium Niobate Ceramics

Lead-free potassium sodium niobate (KNN) ceramics were prepared with lithium and tantalum modification. Structural properties were investigated. Impedance spectroscopy was used as a tool to analyze electrical behavior of ceramics as a function of frequency from 100Hz to 10MHz at a temperature range from 573K to 798K. Neither Li nor Li + Ta modification caused any secondary grain boundary phase, however both of them caused a densification of the ceramic. Increasing the lithium addition was found to decrease the impedance, while the Li + Ta addition drastically increased it. Finally, a temperature induced relaxation process was observed in the samples with the relaxation frequency shifting with temperature.