Electrocaloric refrigeration at cryogenic temperatures

Refrigeration utilizing the electrocaloric effect can be produced with no moving parts and thus, promises to be highly reliable. This paper reviews the principles and experimental results on electrocaloric refrigeration, particularly in the 4–15K temperature range. Many electrocaloric materials were studied but none was found with a sufficiently large reversible electrocaloric effect for a practical refrigerator. The largest effects were seen in a SrTiO3 ceramic, followed by a KTaO3 single crystal. Temperature reductions of about 0.3K at 10K were observed during depolarization from fields of 20 kV/cm. A theoretical model based on the lattice dynamics of displacive dielectrics is postulated to explain the observed temperature changes in such materials.