Cryogenic thermoelectric cooler at operating temperature below 90 K

It is considered the possibility of creating thermoelectric coolers for operating temperatures below 90 K. For these temperatures it is not possible to use a standard circuit of a thermoelement, consisting of two $n$- and $p$-semiconductor legs, connected in a series electrical circuit. In the area of cryogenic temperatures there is only an effective thermoelectric material of $n$-type conductivity, based on solid solutions Bi–Sb. In this case thermoelements composed of thermoelectric $n$-type leg and a passive leg, based on high temperature superconductor (HTSC) were studied. A thermoelectric cooler (module), consisting of six $n$-type legs (extruded crystals Bi$_{0.91}$Sb$_{0.09}$) and passive legs based on HTSC (YBa$_{2}$Cu$_{3}$O$_{7-x}$) films was designed. A magnetic field was used to increase thermoelectric figure of merit $ZT$ of the cryogenic module. For created cryogenic module at hot side temperature $T_h$ = 80 K, a current $I$ = 6.4 A and a voltage $U$ = 0.10 V the maximum value of temperature drop $>$ 13.5 K and a maximum cooling capacity $Q_c>$ 0.36 W were achieved.