Abstract
Ferroelectrics are a class of high dielectric permittivity materials. They are also a group of materials whose crystalline structure possesses a crystallographic axis (polar axis) in the direction of which there is a spontaneous polarization in the polar phase, arising from a displacement of positive and negative centers of charge of the ions in the structure, whose sign can be reversed by a sufficiently high electric field. This chapter discusses the applications of ferroelectric materials in different technological fields, which have been possible because of the wide range of functional properties, mainly dielectric, electrooptical, piezoelectric, and pyroelectric, that they present. Among the perovskite type structure ferroelectrics, because of the advances in the processing of compositional, structural, and microstructurally homogeneous ceramic and thin film materials, pure and modified lead titanate compositions have been the object of great interest from academic and industrial research institutions in the past years. Their potential as piezoelectric and pyroelectric materials is greater than other widely used compositions in special applications such as high frequency ultrasonic transducers, hydrophones, thin film sensors and actuators. Their peculiar properties, such as relatively low dielectric permittivity, high spontaneous polarization and transition temperature, and high electromechanical anisotropy, are in the basis of this interest. The chapter illustrates examples of the changes of the properties of materials with a given composition according to their microstructure, grain and pore size distributions, or texture.
Published Version
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