Photostriction of Ferrites Under Visible Light

Developing photostrictive materials with wide visible light response and desirable photostriction strength remains a great challenge in view of practical applications. Ferrites with rich physical and chemical properties have great potential in this regard. Here, the photostrictive performances of three ferrite materials, CdFe2O4, CaFe2O4, and YFeO3, with different crystal structures are systematically investigated. A large photostriction around 0.1% with a decent photostrictive efficiency of ∼10–11 m3/W is obtained for all the three ferrites under 405, 520, and 655 nm laser illumination. Further investigation reveals that the photothermal effect-induced expansion and the light-induced nonthermal part contribute almost equally to the measured shape deformation. In situ X-ray diffraction with external laser illumination in conjunction with the laser power-dependent Raman spectra analysis indicates that the strong photostriction is not a uniform deformation microscopically, which is closely related to the various degrees of response of the lattice planes to light and mainly attributed to the light-induced distortion of FeO6 octahedrons. Further analysis suggests a bond length rule to account for both the difference between their photostrictive performances and the screening of materials.