Development of High Temperature Thermoelectric Materials and Fabrication of Devices

Thermo Electric Conversion (TEC) is a technique, where heat is directly converted into electrical energy. Development of thermoelectric materials which operate at temperatures up to 700–900C may be an attractive proposition, due to its potential application to the proposed high temperature nuclear reactors. Technologically important high temperature thermoelectric materials and their prototype devices have been developed in the Energy Conversion Materials Section of the Materials Group. Two types of materials i.e. FeSi 2 based intermetallic and mixed oxide ceramic materials have been synthesized and characterized, for high temperature thermoelectric properties, and then they were consolidated and finally integrated into miniature devices. A two–couple miniature device consisting of pins of dimensions 4 x 4 x 20mm, made up of n–type Fe 0.94 Co 0.06 Si 2 and p–type Fe 0.91 Mn 0.09 Si 2 intermetallics, exhibited 8μW power output at 100 oC which increased to 3 mW at 600 oC hot end temperature. On the other hand, a two–couple device made up of oxide ceramic materials, namely, n-type Ca 0.92 La 0.08 MnO 3 , as well as p-type Ca 2.75 Gd 0.25 Co 4 O 9 showed power out put of 18 mW at a hot end temperature of 750 °C.