Dielectric properties, relaxor behavior and temperature stability of (1−x)(K0.4425Na0.52Li0.0375)(Nb0.87Ta0.06Sb0.07)O3-xBa0.4Sr0.6TiO3 ceramics

Abstract

In this paper, Ba0.4Sr0.6TiO3 was added in the (K0.4425Na0.52Li0.0375)(Nb0.87Ta0.06Sb0.07)O3 ceramics to improve the temperature stability. The phase structure, microstructure, dielectric, diffuse phase transition, relaxor behavior and temperature stability of (1−x)(K0.4425Na0.52Li0.0375) (Nb0.87Ta0.06Sb0.07)O3-xBa0.4Sr0.6TiO3 (abbreviated as (1−x)KNLNTS-xBST)ceramics were investigated. The phase structure of these ceramics changed from tetragonal phase to cubic phase with Ba0.4Sr0.6TiO3 additives. A significant reduction in the temperature dependence of relative permittivity occurred at x = 0.15, with ΔC/C298K was around ±15% over the temperature range 273–528 K, and loss tangent, tanδ ≤ 0.03. The result indicated that this material may have great potential for a variety of high temperature applications. The diffuse phase transition and the temperature of the maximum dielectric permittivity shifting toward higher temperature with increasing frequency, which were observed in the (1−x)KNLNTS-xBST solid solution. The dielectric relaxor behavior obeyed a modified Curie-Weiss law. The dielectric relaxor was attributed to the appearance of polar nanoregions owing to the formation of random fields. The ferroelectric characteristic decreased with the addition of BST. These results confirmed that the (1−x)KNLNTS-xBST ceramics can be regarded as an alternative for high temperature lead-free piezoelectrics.