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

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 degrees-cut crystal are d23 = 25 pC/N, sE33 = 7.58 TPa-1, 8T22 = 52.7 80, and k223 = 0.18, which are in excellent agreement with the literature data.