Thermoelectric Power of Gray Tin

Thermoelectric power measurements on gray tin filaments in the temperature range from 77 to 270°K are described. Data are presented for pure samples and for $n$-type and $p$-type samples having various impurity concentrations. Pure samples are always $n$ type, and exhibit a maximum of approximately -100 μv/°K in the neighborhood of 100°K. Other $n$-type samples have a maximum of about -160 μv/°K at somewhat higher temperature, and this maximum shifts to higher temperature as the impurity concentration is increased. The $p$-type samples also exhibit a maximum of the order of 140-160 μv/°K which occurs in the range 90-100°K. All $p$-type samples become $n$ type as the temperature rises, and the crossover point shifts to higher temperature as the impurity concentration increases.