EFFECT OF Sr CONTENT ON DIELECTRIC PROPERTIES OF ((Ba1_xSr )(Tio.5Zro.5)O3j

Abstract

Ceramic materials and single crystals showing ferroelectric behavior are being used in many applications in electronic and optics. A large number of ferroelectric ceramic also exploit properties that are indirect consequence of Ferro electricity, such as dielectric, piezoelectric, pyroelectric and electro-optic properties. Many different applications arising form Ferro electricity and related phenomenon in ceramics have been discussed with their processing techniques. Ferroelectricity is a phenomenon, which was discovered in 1921. The name refers to certain magnetic analogies, though it is somewhat misleading as, it has no connection with iron (ferrum) at all. Rochelle Salt (RS) was the first material found to show ferroelectrics properties such as a spontaneous polarization on cooling below the Curie point, ferroelectrics domains and a ferroelectrics hysteresis loop. A huge leap in the research on ferroelectrics materials came in the 1950's, leading to the widespread use of barium titanate (BaTiO3) based ceramics in capacitor applications and piezoelectric transducer devices. Since then, many other- ferroelectrics ceramics including lead , titanate (PbTiO3), lead zirconate titanate (PZT), lead lanthanum zirconate titanate (PLZT), and relaxor ferroelectrics like lead magnesium niobate (PMN) have been developed and utilized for a variety of applications. With the development of ceramic processing, many new applications have emerged. The biggest use of ferroelectric ceramics have been in the areas such as dielectric ceramics for capacitor applications, ferroelectric thin films, for non-volatile memories piezoelectric materials for medical ultrasound imaging and actuators and electro-optic materials for data storage displays. Piezoelectric was originally discovered by Pierre and Jacque Curie in 1880, who found that electric charges developed on the surface of crystals, when they were mechanically stressed. Thus the development of electrical charges (or voltage) under the application of mechanical pressure is called Piezoelectric effect. However, in many applications, piezoelectric materials are also utilized for the reverse effect, i.e., the deformation (strain) of a material when exposed to an applied electric field. This response is called the converse piezoelectric effect and it is useful for actuator applications. In contrast, the direct piezoelectric effect is used in what are typically referred to as sensor application.