Electrical conductivity and thermoelectric power of alloys in the As-Te and As_40-xTe_60-yIn_x+y molten systems

Experimental investigation has been made of the variation of electrical conductivity and thermoelectric power with composition and temperature in the As-Te and As_40-xTe_60-yIn_x+y molten systems. For the As-Te system, the electrical conductivity, sigma , is a continuous and decreasing function of the arsenic content over the range 5-55 atomic per cent arsenic; while the thermoelectric power is a continuous and increasing function of the arsenic content over the range of 15-55 atomic per cent arsenic. The temperature coefficient of conductivity, d sigma /dT, is positive for all investigated alloys. Just above the melting points of these alloys, in a temperature range which increases with increasing As content, the conductivity activation energy is constant and independent of composition. Thereafter, the activation energy decreases with temperature. The behaviour of the thermoelectric power, S, is consistent with the behaviour of the electrical conductivity discussed above. Additions of small quantities of indium to replace either arsenic or tellurium in As₂Te₃ lead to a decrease in conductivity.