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5.3 Ferroelectric Ceramics
Ferroelectric effect was first observed in Rochelle salt KNaC4H4O6.4H2O by Czech scientist Roger Valasek in 1921. Afterwards, for years the discovery did not raise much excitement possibly due to the world war. However, after a few decades, renewed technological interest led to much more extensive studies and a better understanding.
In the subsequent years, many materials were discovered and were of technological interest as they were employed into a variety of applications. Among various categories of ferroelectric materials following stand out either due to interest in the structure or in the properties:
Tri-glycine sulfate and isomorphous materials Pottasium dihyrogen phosphates and isomorphous materials -
Barium titanate and other perovskite structured compounds such as KNbO3, PbTiO3 etc
Complex oxides such as Aurrivillious compounds Rochelle Salt and similar compounds Ferroelectric Sulfates
Among the above, perovskite related compounds have been studied most, primarily due to their exciting properties and reasonably high transition temperatures, making them attractive for various applications.
In the following section, we will look some of the structural and thermodynamic features of these materials, with main emphasis on perovskite compounds for the sake of illustration.
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