Reduction in thermal conductivity of Bi–Te alloys through grain refinement method

Ternary alloys of thermoelectric materials Bi–Sb–Te and Bi–Se–Te of molecular formula, Bi0·5Sb1·5Te3 (p type) and Bi0·36Se0·064Te0·576 (n type), were prepared by mechanical alloying method. The preparation of materials by mechanical alloying method has effectively reduced the thermal conductivity by generating a large number of induced grain boundaries with required degree of disorder. The process of frequent milling was adapted for grain refinement. Substantial reduction in thermal conductivity was achieved due to nano-structuring of these alloys. Thermal conductivity values were found to be very low at room temperature, 0·5 W/mK and 0·8 W/mK, respectively for p and n type materials.