Phase transitions, phase coexistence, and piezoelectric switching behavior in highly strained BiFeO(3) films.

Highly strained BiFeO3 films transition into a true tetragonal state at 430 °C but remain polar to much higher temperatures (∼800 °C). Piezoelectric switching is only possible up to 300 °C, i.e., at temperatures for which strain stabilizes the stripe-like coexistence of multiple polymorphs.