Double Hysteresis Loops and Large Negative and Positive Electrocaloric Effects in Tetragonal Ferroelectrics

<p>Fig. 7 (A) Temperature–electric field phase diagram of the BaTiO3 nanoparticles under sustained compression σ33* = −0.002, where the applied electric field is reduced from E3* = 1.5 to a specific value. Symbols: ★ c phase, ab phase, paraelectric phase, abc phase. (B) Domain structures under sustained compression σ33* = −0.002 and applied electric field E3* = 0.2 at temperatures ranging from 283 K to 393 K.</p> <p>