Nanosecond electric pulse-induced ultrafast piezoelectric responses in Co3+ substituted BiFeO3 epitaxial thin films

Understanding the ultra-fast dynamics of ferroelectric materials is essential for advancing the development of next-generation high speed electronic and photonic devices. Here, the ultrafast piezoelectric response of cobalt-substituted BiFeO₃ (BiFe_1-xCo_xO₃) with x = 0.15, consisting of morphotropic phase boundary of monoclinic M_C and M_A –type phases is investigated. The real-time piezoelectric response in (001)-oriented BiFe_0.85Co_0.15O₃ (BFCO) epitaxial thin film was monitored using the time-resolved X-ray microdiffraction technique under an applied electric field with pulse widths 70 ns and 100 ns. The BFCO thin film yielded a high piezoelectric strain of approximately 0.53 % along [001] direction, with a giant c/a ratio (∼1.26) at an electric field of 1.3 MV/cm and a pulse width of 100 ns, with a piezoelectric coefficient ($d_{33}$) of 40 pm/V. This finding is an important step towards the development of a high performance lead-free piezoelectric material for ultrafast operations in advanced technological applications.