Fabrication of textured Sr2Na0.9K0.1Nb5O15 ceramics: Anisotropy in structures and electrical properties

Highly textured Sr2Na0.9K0.1Nb5O15 (SKNN) ceramics were fabricated by reactive templated grain growth method using acicular Sr2KNb5O15 (SKN) templates. CuO (1 wt.%) was used as sintering additive. SKN templates were aligned in matrix powders of SrNb2O6 and NaNbO3 via tape casting and sintered at higher temperatures to obtain texture morphology. Through carefully controlling the processing conditions, a texture fraction of 86% was obtained. The structure evolution was explained by liquid-phase-assisted growth mechanism, in which the whole process was divided into 3 steps according to priority: phase formation stage, densification stage, and texture development stage. The textured ceramics exhibited anisotropic properties with the highest electrical properties obtained in c-axis direction: ɛr = 2212, ɛm = 4869, Pr = 15.92 μC cm−2 and d33 = 82 pC N−1, showing that reactive templated grain growth method is very effective to improve the physical properties of SKNN ceramics.