Thermal conductivity can be altered by applying an electric field to an antiferroelectric material or a pressure to a ferroelectric material, thereby inducing a phase transition. The materials have compositions close to a phase boundary separating the ferroelectric and antiferroelectric phases, such as PbZr.sub.1-xTi.sub.xO.sub.3 (with x.ltoreq.0.08), Pb(Nb.sub.xZr.sub.ySn.sub.zTi.sub.1-y-z)O.sub.3, (Pb,La)(Zr.sub.ySn.sub.zTi.sub.1-y-z)O.sub.3, NaNbO.sub.3, Bi.sub.0.5Na.sub.0.5TiO.sub.3, or AgNbO.sub.3. By inducing a phase transition using either an electric field or pressure, the resulting change in the thermal conductivity can be used to provide a thermal switch or a continuous thermal conductivity tuning element.
STATEMENT OF GOVERNMENT INTEREST
 This invention was made with Government support under contract no. DE-AC04-94AL85000 awarded by the U.S. Department of Energy to Sandia Corporation. The Government has certain rights in the invention.