Pseudo-first-order phase transition for ultrahigh positive/negative electrocaloric effects in perovskite ferroelectrics

<p>Figure 1. The free energy versus polarization of ferroelectric nanoparticles with and (A) schematic drawing of a 3D energy landscape for a free-standing nanoparticle at T=333 K, (B–D) the minimum free energy paths versus the orientation angle with respect to sustained mechanical compressions of , and −0.003, respectively, (E) The temperature–stress phase diagram of the BaTiO3 nanoparticles, symbols: c phase,ab phase, paraelectric phase. (B–D) are plotted by the analytic solution of Landau–Devonshire free energy, while the phase diagram (E) is plotted based on the remnant polarization determined from phase field calculations. Symbols of solid and open balls indicate the positions of the ab and c phases, where solid and open balls denote the phases which will be survived and un-survived, respectively, after the applied field decreases from its maximum value to zero.