Electrocaloric effects across room temperature in multilayer capacitors

A growing number of cooling devices^1-4 exploit large electrocaloric effects associated with a supercritically driven first-order ferroelectric phase transition in multilayer capacitors of PbSc_0.5Ta_0.5O₃ (PST)⁵. However, these multilayer capacitors only operate above the room-temperature Curie temperature and require an energetically expensive 42-day anneal for high B-site order to maximize latent heat. Here we show that exaggerating valence mismatch through dilution with PbMg_0.5W_0.5O₃ (PMW) maintains high B-site order and latent heat with no anneal, while disrupting dipolar order to reduce the Curie temperature as low as 230 K. Our multilayer capacitors of PST-PMW show supercritical electrocaloric effects of about 3 K across and well below room temperature owing to 17.1 V μm^-1 fields we apply >10⁷ times without breakdown. Using our multilayer capacitors in an ideal fluid regenerator and assuming work recovery yields cycle efficiencies of 70-90%. Taken together, our findings imply that multilayer capacitors of PST-PMW should now replace multilayer capacitors of PST in electrocaloric prototypes to permit electrocaloric refrigeration.