Regulation of the Ordered Occupation of Heterovalent B-Site Ions in (1 - x)PbSc0.5Ta0.5O3-xPbSc0.5Nb0.5O3 Solid Solutions and Its Influence on the Electrocaloric Effect.

The development of integration and miniaturization of components makes localized overheating a great challenge in microelectronic equipment, for which the electrocaloric (EC) refrigeration provides a promising solution. PbSc0.5Ta0.5O3 (PST) is a normal ferroelectric material with a large EC cooling temperature change (ΔT), but its temperature range (Tspan) cannot fully cover the requirements of chip cooling yet. We proposed an efficient approach by introducing PbSc0.5Nb0.5O3 (PSN) relaxor ferroelectric with a wide Tspan and forming the solid solution of (1 - x)PST-xPSN (0 ≤ x ≤ 1) ceramics. With more PSN content, the arrangement of heterovalent B-site ions gradually changes from partially ordered to disordered accompanied by a diffused phase transition. With the increase of PSN content, the EC ΔTmax shows a U-shaped trend and the Tspan increases due to the simultaneous increase of polarization and diffusiveness. Especially, the x = 0.8 ceramic has a fairly large EC ΔTmax of 1.25 K (@40 kV cm-1) at 75 °C with a wide Tspan of 93 °C (48-141 °C). This work not only broadens the application range of EC refrigeration, but also provides a targeted material design strategy to address these emerging requirements.