A growing number of cooling devices exploit large electrocaloric (EC) effects associated with a supercritically driven first order ferroelectric phase transition in multilayer capacitors (MLCs) of PbSc0. 5Ta0. 5O3 (PST). However, these MLCs only operate above the room temperature Curie temperature, and require an energetically expensive 42-day anneal for high B-site order to maximise latent heat. Here we show that exaggerating valence mismatch via dilution with PbMg0. 5W0. 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 MLCs of PST-PMW display supercritical EC effects of ~3 K across and well below room temperature due to 17. 1 V μm^-1 fields we apply >10⁷ times without breakdown. Employing our MLCs in an ideal fluid regenerator and assuming work recovery yields cycle efficiencies of 70-90%. Taken together, our findings imply that MLCs of PST PMW should now replace MLCs of PST in EC prototypes to permit EC refrigeration.
Mathur et al. (Thu,) studied this question.