Plate-like Ca₃Co₄O₉: A novel lead-free piezoelectric material

Large-size Ca₃Co₄O₉ microplates in the range of 10 μm to 18 μm, were prepared by using molten salt synthesis method. The piezoelectric properties of Ca₃Co₄O₉ were reported in the first time. The crystal structure was characterized by X-ray diffractometry along with Rietveld refinement of lattice parameters. In situ piezoresponse force microscopy (PFM) measurements demonstrated that a maximum piezoelectric strain coefficient d*₃₃ of 95.1 pm/V was obtained, rooting in the non-centrosymmetric and anisotropic crystalline structure. This work suggests that the misfit-layered cobaltite oxides can be considered to be a promising alternative lead free piezoelectric material.