Ionic conductivity, ferroelectricity and chemical bonding in TKWB type ceramics of the K₆Li₄Ta₁₀O₃₀-Pb₅Ta₁₀O₃₀ system

Abstract

Correlations between Curie temperature and chemical bonding were found in ferroelectric tetragonal potassium tungsten bronze type ceramics [TKWB] using the extended Hckel tight-binding (EHTB) method. The influence of Pb for K,Li substitution is shown. AC complex impedance measurements were performed on ceramics with compositions corresponding to Pb_5xK_6(1–x)Li_4(1–x)Ta₁₀O₃₀ (PKLT) in a wide temperature range. The conductivity relaxation parameters of Li⁺ conducting PKLT ceramics were determined. Transport properties in these materials appear to be due to a Li⁺ ion hopping mechanism. The influence of the substitution 6K⁺+4Li⁺→5Pb²⁺ on the mobility is discussed with the assistance of the results obtained from EHTB calculations.

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