Experimental Validation of One-Dimensional Model of an Ideal Bimorph Actuator Provided on Bidomain Lithium Niobate

[Display omitted] •Displacements and impedance of a cantilevered bidomain LiNbO3 crystal can be described by a 1D model of an ideal bimorph.•Solving the inverse problem of fitting the experimental points allows one to obtain the material’s constants.•The predictability of the behavior of LiNbO3 bimorphs is a unique property for precise lead-free actuators. The study demonstrates that the dynamic characteristics of piezoelectric bimorph actuators based on bidomain lithium niobate (BLN) single crystals are accurately described by an analytical one-dimensional (1D) model of an ideal bimorph. Our observations show that displacements and an electric impedance of the BLN-based bimorphs can be predicted without use of any sophisticated lumped circuit models, equations with handpicked “effective” values of material’s constants or finite element method. The experimental data were measured by means of laser interferometry and impedance spectroscopy and then fitted with the equations predicted by the 1D model. Solving the inverse problem for the experimental points we calculated the transverse piezoelectric coefficient, longitudinal mechanical compliance, dielectric permittivity, and piezoelectric coupling coefficient of the material. The obtained values of the material constants of the lithium niobate y + 128°-cut crystal are d23 = 25 pC/N, s33E = 7.58 TPa−1, ε22T = 52.7 ε0, and k232 = 0.18, which are in excellent agreement with the literature data.