Large electrocaloric effects in unannealed multilayer capacitors of partially ordered lead scandium tantalate

Multilayer capacitors of PbSc0.5Ta0.5O3 with good B site cation order (S₁₁₁ ~ 0.9-0.96) are driven by supercritical fields of 15.8 V μm⁻¹ in prototype coolers, such that large electrocaloric effects arise over a wide range of temperatures and peak to give thermocouple measured temperature jumps of |∆Tj| ~ 4.0 K near room temperature. However, the high degree of B site order requires an energetically expensive 42 day high temperature anneal that would be economically expensive and environmentally damaging in mass production. Here we report that the performance reduction (4.0 K → 3.1 K) for unannealed multilayer capacitors of PbSc0.5Ta0.5O3 with partial B site order (S₁₁₁ ~ 0.6) is surprisingly small because reduced latent heat is mitigated by high-field electrocaloric effects in the induced ferroelectric phase. Eliminating the anneal without unduly compromising performance should render unannealed multilayer capacitors of PbSc0.5Ta0.5O3 attractive for applications.