The piezoelectric performance and anisotropy factors of modern threec-component composites

Piezo-active composites are often regarded as two-component materials with either one or two piezoelectric components, such as ferroelectric ceramics, ferroelectric single crystals or polymers. The important ability to convert mechanical energy into electric energy and vice versa is achieved in these composites via electromechanical coupling and creating the optimal microgeometric features. In the last decade, a new trend in the study of the piezo-active composites is concerned with a further modification of its structure by introducing a third component that may influence the piezoelectric effect, electromechanical coupling factors and anisotropy of electromechanical properties in a wide volume-fraction range of the components. In the present chapter, we analyse the physical and microgeometric factors that improve piezoelectric sensitivity and the anisotropy of the piezoelectric properties and electromechanical coupling factors in three-component composites based on poled ferroelectric ceramics. The studied composites are characterised by a number of elements of connectivity, such as 1–3, 2–2 and 0–3, and the role of these elements in forming the anisotropic piezoelectric response is discussed. Examples of the large piezoelectric anisotropy and the considerable anisotropy of electromechanical coupling factors of the three-component composites are considered in the context of their potential piezotechnical applications, such as sensors, transmitters and energy harvesting devices.