Modeling of Olsen cycle for pyroelectric energy harvesting and assessment of abnormal electrocaloric effect in ferroelectric single crystals

The energy conversion potential of ferroelectric materials originating from their phase transitions, in particular temperature ranges and electric field values, is very promising. Pyroelectric energy harvesting consists of directly converting thermal energy into electrical energy. Due to its high energy conversion potential, the Olsen cycle is the most favorable for pyroelectric energy harvesting. This cycle includes two isothermal and two constant electric field branches. In this study, the Olsen cycle was modeled, then varying temperatures and applied electric field directions for different crystal orientations were simulated. Polarization responses were obtained via the Landau-Devonshire theory. Then, an innovative way to model the electrocaloric effect was proposed; experimental results and first-principle calculations confirmed the simulation results. The resulting negative electrocaloric effect due to crystal orientation, previously reported in the literature, has been successfully simulated through a phenomenological approach. Finally, we identified which phase transitions are interesting for pyroelectric energy harvesting applications depending on crystal orientations while obtaining an energy density in the order of asymptotic to 10(2 )mJ / cm 3. This value corresponds to previous results in the literature. Published under an exclusive license by AIP Publishing.

Automated summary

The energy conversion potential of ferroelectric materials, specifically in temperature ranges and electric field values, is highly promising. Pyroelectric energy harvesting, which converts thermal energy directly into electrical energy, is most effectively achieved through the Olsen cycle. This study successfully modeled the Olsen cycle, simulating varying temperatures and electric field directions for different crystal orientations. The results confirmed the negative electrocaloric effect previously reported, and identified the phase transitions most suitable for pyroelectric energy harvesting applications, with an energy density in the order of 10(2) mJ/cm 3.