Prospects for Peltier cooling of the cuprate superconductors

The figure of merit z of commercial Peltier modules has been measured to drop from z=2.3/spl times/10/sup -3/ K/sup -1/ with the warm end near 295 K to z=4/spl times/10/sup -4/ K/sup -1/ with the warm end at 80 K. Therefore, for reaching the superconducting temperature range even for the cuprates with the highest critical temperature T/sub c//spl ap/130 K, new thermoelectric materials with their maximum value of z around 150 K or lower must be developed. We present experimental results on p- and n-doped compounds of the family Bi/sub 2-x/Sb/sub x/Te/sub 3-y/Se/sub y/ showing improved values of z at 150 K and below. We have studied in particular the influence of sintering.