Improved Thermoelectric Properties of Bi-M-Co-O (M = Sr, Ca) Misfit Compounds by Laser Directional Solidification

摘要

In this work, improvement of the thermoelectric properties of bulk samples due to texture developed by a directional laser-assisted solidification process (laser floating zone melting method) is reported for cobaltite materials with compositions Bi₂Sr₂Co_1.8O _y and Bi₂Ca₂Co_1.7O _y . Sample composition and microstructure have been studied using x-ray diffraction and scanning electron microscopy. Thermoelectric properties have been measured between 4 K and 300 K by simultaneous determination of electrical resistivity and thermopower. All textured samples showed remarkable increase of power factor values as compared with conventional sintered ceramics.