Reaction mechanism of room-temperature synthesized n-Bi2Te3 and high thermoelectric performance p-(Bi,Sb)2Te3-Te using nanosized precursor methods: A novel and energy-efficient production method

Bi2Te3-based thermoelectric materials remain the largest segment of sales in thermoelectric products. Therefore, it is desirable to manufacture Bi2Te3-based thermoelectric materials with energy-efficient synthesis conforming to the 6th principle for green chemistry. We present the formation mechanism for room-temperature synthesized n-Bi2Te3 nanocomposites involving interaction between atoms of Bi and Te with high yield (near 100%) without using any organic substance. It is found that nanosized Bi and Te would first form before the growth of n-Bi2Te3. As such, to shorten the growth period of 14 days, we develop a procedure of producing p-Bi0.45Sb1.55Te3 using nanosized precursors of Bi, Sb, and Te to speed up the process. These nanosized precursors are obtained in one day at room temperature, followed by heat treatment. As a result, the zT is 1.27 at 400 K for p-(Bi, Sb)(2)Te-3-Te composite and zT = 1 for n-Bi2Te3 at 425 K.