Comparing investigation of the anisotropic thermoelectric properties of textured KSr₂Nb₅O₁₅ ceramics

High ZT at a certain direction is highly desirable for tungsten bronze structure material which has anisotropic lattice structure. The anisotropic thermoelectric properties of KSr₂Nb₅O₁₅ were studied using first-principles calculations. KSr₂Nb₅O₁₅ has a high ZT of 1.379 in the ∥c direction, which is 16.65 times larger than that in the ⊥c direction. In addition, KSr₂Nb₅O₁₅ textured ceramics were prepared by reactive templated grain growth, and their anisotropic thermoelectric properties were studied. The sample along the ∥c direction has a power factor of 0.236 mW/(mK²), which exhibits much larger thermoelectric properties than that along the ⊥c direction. Both the calculated results and experimental results have good consistency and verify the obvious anisotropic thermal properties of KSr₂Nb₅O₁₅. Furthermore, the mechanism of the anisotropy of the thermoelectric properties of KSr₂Nb₅O₁₅ is simply clarified. This research provides a basis for improving the thermoelectric performance of KSr₂Nb₅O₁₅ ceramics.