An analysis of lead-free (Bi_0.5Na_0.5)_0.915-(Bi_0.5K_0.5)_0.05Ba_0.02Sr_0.015TiO₃ ceramic for efficient refrigeration and thermal energy harvesting

This article demonstrates the colossal energy harvesting capability of a lead-free (BiNa)-(Bi K)BaSr TiO ceramic using the Olsen cycle. The maximum harvestable energy density estimated for this system is found to be 1523 J/L (1523 kJ/m) where the results are presented for extreme ambient conditions of 20-160 °C and electric fields of 0.1-4 MV/m. This estimated energy density is 1.7 times higher than the maximum reported to date for the lanthanum-doped lead zirconate titanate (thin film) system. Moreover, this study introduces a generalized and effective solid state refrigeration cycle in contrast to the ferroelectric Ericson refrigeration cycle. The cycle is based on a temperature induced polarization change on application of an unipolar electric field to ferroelectric ceramics.