The thermoelectric properties of n-type single crystals of bismuth seleno-telluride and their relationship to those of pressed powder compacts

In preparing ingots of thermoelectric materials by pressing anisotropic powders partial alignment occurs. A theoretical model is proposed which enables the electrical and thermal conductivities of the ingot to be predicted. For the purpose of this prediction measurements of the conductivities in principal directions have been made on good single crystals of alloys in the range 0–20 mol.% Bi₂Se₃ in Bi₂Te₃. The theory is compared with pressed powdered materials from this system. It is concluded that some alignment occurs.