3. Experimental Studies on Effective Properties and Related Parameters of Piezo-Particulate Composites

Numerous experimental results on the effective dielectric, pyroelectric and piezoelectric properties and related parameters of piezo-particulate composites based on ferroelectric ceramics are described and analysed. The effective properties of the composites structured by means of dielectrophoresis (0–3 and/or 1–3 connectivity patterns) are compared to the properties of related random (or non-structured) composites with 0–3 connectivity. The influence of the composite microgeometry and properties of the components on the effective properties is discussed. Large values of maximum of the piezoelectric coefficient \(g_{33}^{*}\) describing piezoelectric sensitivity are achieved in the structured composite. The considerable increase of \(g_{33}^{*}\) is a result of forming a porous structure in the polymer matrix of the composite. Examples of the influence of the porous (foam) polymer matrix on the piezoelectric coefficient \(g_{33}^{*}\) are considered for composite based on the ferroelectric PZT ceramic. High-temperature piezo-active composites exhibit thermal stability of both the dielectric and piezoelectric properties in the presence of the ferroelectric ceramic component with the high Curie temperature T_C and due to the considerable thermal stability of the dielectric properties of the polymer matrix.