YbCu2Si2–LaCu2Si2 Solid Solutions with Enhanced Thermoelectric Power Factors

Abstract

Cryogenic Peltier coolers are ideal for cooling infrared sensors on satellites. To make these thermoelectric devices a realistic option for this application, the efficiency of thermoelectric materials at cryogenic temperatures must be substantially enhanced. Intermediate valence Yb-based compounds have large peaks in the Seebeck coefficient at low temperatures; to optimize these materials this must be understood. We created solid solutions between the intermediate valence compound YbCu2Si2 and an isostructural compound LaCu2Si2 to manipulate the temperature at which the Seebeck coefficient peaks and to maximize zT by reduction of lattice thermal conductivity. An enormous power factor of 110 mu W/cm K-2 at 100 K and a maximum zT of 0.14 at 125 K were achieved for one of these solid solutions.