Invited
Outstanding electrocaloric cooling and pyroelectric energy harvesting with first order phase transition in ceramics

Multilayer capacitors made of ceramics have multiple virtues. Whereas they were initially developed for their large capacitance, they proved to be also interesting for cooling purposes, if the ceramic exhibits large electrocaloric properties such as lead scandium tantalate (PST). Indeed, they can exhibit up to 5.5 K of adiabatic variation of temperature when an external voltage is applied [1]. As detailed in this talk, several multilayer capacitors can be assembled in a regenerator to amplify the total variation of temperature, which can reach 13 K when a fluid is used to transport heat [2]. Besides, the same multilayer capacitors made of PST exhibit excellent pyroelectric properties and can transform heat in electricity. We recently observed that electrical energy density as large as 4.4 J cm-3 can be generated with these multilayer capacitors through proper thermodynamic cycles [3]. We also built an energy harvester that can generate 11 J of energy in one cycle between 10°C and 100°C with only 42 g of active PST. These outstanding cooling and energy harvesting properties stem from a strong first order phase transition occurring in PST combined with very low leakage current enabling long cycles and high reliability.

[1] Nair, B. et al. Large electrocaloric effects in oxide multilayer capacitors over a wide

temperature range. Nature 575, 468–472 (2019).

[2] Torelló, A. et al. Giant temperature span in electrocaloric regenerator. Science 370,

125–129 (2020).

[3] Lheritier, P et al., Large harvested energy with non-linear pyroelectric modules, Nature 609 (7928), 718-721 (2022).