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Abstract
The dielectric properties of K1−x, Lix, Tal−y, Nby 03(KLTN) crystals as functions of the frequency, temperature and electric field are presented. The dielectric measurement were conducted on several crystals with moderate Nb concentration, 10%–40% and small Li concentration, <I%. In this article we present the results for two representative samples, one with 16% of Nb and 0.8% of Li and the other with 36% of Nh and 0.6% of Li.
The dielectric permitivity in the vicinity of the phase transition in the sample with 16% of Nb increases when an electric field is applied. This increase is connected with the sign change from positive to negative of y, the coefficient of p4 in the free energy function. This result suggests that the phase transition in KLTN crystal is first order phase transition. A relaxation process with activation energy of 0.107eV and a high temperature frequency of 3×1011Hz was found. This relaxation process was attributed to Li 90° flips.