Improving the photostriction of BiFeO3-based ceramics by bandgap and domain size engineering

The photostrictive properties of (1-x)BiFe0.96Mn0.04O3-xBaTiO3 (0.23 < x < 0.38) ceramics were investigated using the solid-state synthesis method. Appropriate addition of manganese significantly reduces the bandgap, while the introduction of BaTiO3 changes the phase structure from rhombohedral to pseudo-cubic and significantly optimizes the ferroelectric domain size. The photostriction was observed in the visible light wavelength range with a response time of around 45 s. Specifically, both enhanced photo-induced deformation around 1.27x10-3 and high photostrictive efficiency of 8.40x10-12 m3 W-1 were obtained for the 0.67BiFe0.96Mn0.04O3-0.33BaTiO3 ceramics. The significantly narrow bandgap (-1.89 eV) and the increased domain wall density due to reduction in ferroelectric domain size enhance the separation and motion of photogenerated carriers, and consequently improve the photostrictive performance. Besides, the prominent Raman peak redshift with the increasing of Raman power reveals the enhanced FeO6 octahedral distortion and stretching vibration of Fe-O bond, which indicates the lattice expansion caused by the photoexcited charge carriers.