Hydrostatic piezoelectric parameters of lead-free 2–0–2 composites with two single-crystal components: Waterfall-like orientation dependences

Abstract

A system of hydrostatic parameters is studied in novel 2–0–2 composites that contain two lead-free piezoelectric single-crystal components. The ferroelectric domain-engineered alkali niobate-tantalate-based single-crystal layer promotes large values of the piezoelectric coefficients g33∗ and gh∗, hydrostatic squared figure of merit dh∗gh∗, and hydrostatic electromechanical coupling factor kh∗ of the composite wherein the 0–3 Li2B4O7 single crystal/polyethylene layers are adjacent to the aforementioned single-crystal layer. Hereby, the role of the elastic anisotropy of the 0–3 layer is emphasized. An orientation effect concerned with rotations of the crystallographic axes of the piezoelectric Li2B4O7 single crystal in the 0–3 layer is first studied. It is shown that the orientation of the crystallographic axis Z of the Li2B4O7 single crystal in the polymer matrix strongly influences the piezoelectric properties and hydrostatic parameters of the composite. Examples of the so-called waterfall-like orientation dependences of the hydrostatic parameters are analyzed. The composite based on the domain-engineered [Lix(K1−yNay)1−x](Nb1−zTaz)O3:Mn single crystal is of interest due to gh∗∼102mV⋅m/N, dh∗gh∗∼10−10 Pa−1, and kh∗≈0.70–0.75 in the studied volume-fraction and orientation ranges, and these hydrostatic parameters are to be taken into account in the field of piezotechnical, hydroacoustic, and energy-harvesting applications.

Keywords

• lead-free piezo-active composite
• piezoelectric properties
• hydrostatic parameters
• orientation effect