GB865541A - Improvements in or relating to thermoelectric devices - Google Patents

Abstract

865,541. Thermocouples. WESTINGHOUSE ELECTRIC CORPORATION. April 9, 1958 [April 16, 1957], No. 11202/58. Class 37. A thermocouple comprises one element consisting of a compound of the formula Li m A (1-m) B or Al n A (1-n) B where A represents one or more of the elements Mn, Fe, Co, Cu and Zn, B represents S, Se, Te or O, and m and n have values between 0.001 and 0.1. Preferred thermocouples utilize a member made of one of the compounds Li m A (1-m) B which have positive thermoelectric powers, connected to a member made of one of the compounds Al n A (1-n) B which have negative thermoelectric powers. Alternatively a member of Li m A (1-m) B may be used in combination with a member made of a compound MZ (1-a) , and a member Al n A (1-n) B used with a member made of a compound MZ (1+a) , where M is at least one element selected from Cr, Mn, Fe, Ni, Co, and. Cu, Z is at least one of the elements Se, Te, S, As, Sb, Bi and a has a value in the range 0.001 to 0.1. Such an arrangement used as a heat pump is shown in the Figure. The thermocouple members 12, 14 are joined within an insulated chamber by a strip 16 of copper or silver soldered to metal layers 18, 20, vacuum evaporated or ultrasonically brazed on the elements. The strip 16 and strips 22, 24 similarly soldered to the other ends of the elements outside the chamber may be finned to facilitate absorption and dissipation of heat. With the circuit shown, heat is absorbed at strip 16 and rejected at strips 22, 24. A number of such couples may be connected in series to increase the cooling effect. The couples may also be used as current generators by placing one set of junctions in a furnace and cooling the other set. Couples consisting of any of the compounds and a metal, e.g. copper, silver, copper alloys, silver alloys and molybdenum, are also useful. Materials of the formula MZ (1Œa) specifically described are non-stoichiometric compounds of chromium or manganese with tellurium, arsenic, antimony or bismuth, e.g. manganese arsenide, telluride, bismuthide and antimonide and chromium telluride, which are made by intimately mixing the correct proportions of the elements, firing in a protective atmosphere and compressing and sintering the resulting powder. The compound Li .01 Zn .92 Cu .07 O is made by mixing suitable proportions of lithium peroxide, zinc oxide and cupric oxide, compressing, and heating in a sealed container to 900‹ C. for several hours. The resulting non-homogeneous mass is fused, and recrystallized by slowly withdrawing from a furnace to form a homogeneous, preferably monocrystalline body. A compound of the formula Al n Cu (1-n-p) Zn p O may be made by heating an alloy of copper with 10 atomic per cent of aluminium in an oxidizing atmosphere and mixing the resulting oxide with a suitable amount of zinc oxide. The mixture is then melted and resolidified to a homogeneous mass. Specification 865,542 is referred to.