Device and method for measuring flexoelectric coefficient of thin film material with adjustable strain gradient

Abstract

The invention discloses a thin film material flexoelectric coefficient measuring device capable of regulating and controlling strain gradient and a method thereof. The device having a sandwich structure formed by two layers of matrix beams with the same lengths, widths and thicknesses and a test film which is arranged between the two layers of beams and has the same length and width as the beams comprises a four-point 1 / 4 bending clamp including two upper pressing heads and two stress supporting pieces, a small-load loading instrument for loading the four-point 1 / 4 bending clamp, a controllerbeing connected with the small-load loading instrument and being used for controlling the loading force and loading frequency, and a charge amplifier and an oscilloscope sequentially connected with the small-load loading instrument. Under loading control of four-point 1 / 4 bending clamp force application points, namely two upper pressing heads, regulation and control of strain gradient in flexoelectric coefficient measurement are realized; the method is simple, the structural model is low in cost and easy to implement, the difficulty of strain gradient control in flexoelectric coefficient measurement is reduced, and the difficulty of flexoelectric coefficient measurement of the thin film material is reduced.

Description

technical field [0001] The invention relates to the technical field of electromechanical coupling in material science, in particular to a device and method for measuring the deflection electric coefficient of thin film materials with adjustable strain gradients through a sandwich structure and a four-point 1 / 4 bending model. Background technique [0002] Electromechanical coupling exists widely in artificial and natural materials. The piezoelectric effect can realize the mutual conversion between mechanical energy and electrical energy, and is an important part of modern high-performance functional devices. The piezoelectric effect generally refers to electrical polarization caused by strain in a crystal, or deformation of a material under the action of an electric field. Crystallographic theoretical studies have shown that only crystals with non-centrosymmetric microstructures may have piezoelectric effects. Different from the piezoelectric effect, the flexoelectric effec...

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Problems solved by technology

However, at present, the measurement of the transverse flexoelectric coefficient of most materials adopts the method of bending the cantilever beam. In view of the uneven distribution of the strain gradient along the length of the beam in the bending experiment of the cantilever beam, it is bound to affect the measurement results of the flexoelectricity.

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