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

Abstract

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 100 Hz to 10 MHz at a temperature range from 573 K to 798 K. 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.

Comprehensive investigation of structural, dielectric and local piezoelectric properties of KNN ceramics

“…The value of FWHM evaluated from the normalized spectrum is greater than log 2þ p 3 2À p 3 , and this indicates the non-Debye type behavior which is well supported by complex modulus plot. 21,22 The ac conductivity ( ac ) of the samples was calculated from the dielectric data using the relation ¼ ω""0 tan δ where "0 is the vacuum permittivity and ω is the angular frequency. The conductivity of all the samples was estimated in the paraelectric temperature range 430-500 ○ C. The variation of ln ac with temperature (KÀ1) is shown in Fig.…”