Investigations the effect of crystallographic texturing on electrocaloric property in lead free BaTiO3 VE (K,Na)0.5Bi0.5TiO3 ferroelectric ceramics

In this thesis, effects of composition and crystallographic anisotropy on electrocaloric effect in lead free ferroelectrics was investigated. Lead free bulk ceramic systems of BaTiO3 and 0.82(Na0.5Bi0.5TiO3)-0.18(K0.5Bi0.5TiO3) were produced via templated grain growth (TGG) method and gained high degree of crystallographic texturing. The shaping method of bulk ceramics was tape casting. Matrix powders used to produce ferroelectric ceramics were synthesized by solid state mixed oxide method. BaTiO3 and Na0.5Bi0.5TiO3 platelet powders were utilized as template particles for two ceramic systems so that fabricated high degree of textured microstructures. For both in two ceramic systems, effects of degree of texturing with respect to different amount of templates on electrocaloric properties was investigated. The high degree of texturing was obtained in contain 10 wt.% platelet ceramics. The electrocaloric temperature change was observed for BT ceramic material, 1.3K and 0.82(Na0.5Bi0.5TiO3)-0.18(K0.5Bi0.5TiO3) ceramic material, 1.68K. These results are one of the highest values compared to the same compositions in the literature. In addition, degree of crystallographic texturing contributed positive effect on electrocaloric temperature change for BT ceramics.