Studies of Lead-Free Ferroelectric Materials Derived from the Agnbo3-Based Solid Solution Systems

The lead-free ferroelectric materials, (1-x)AgNbO3-xKNbO3 (AN-KN) and (1-x)AgNbO3-xK0.5Na0.5NbO3 (AN-KNN) solid solutions were prepared in the form of ceramics by solid state reaction under controlled O2 atmosphere. The structure and properties of these two systems have been systematically investigated. The electric study of the AN-KN and AN-KNN ceramics suggests that the dielectric, ferroelectric, and piezoelectric properties in AN are improved significantly by the substitution of KN and KNN, indicating that these materials are promising for a wide range of applications such as ceramic capacitors, electromechanical transducers, and non-volatile memory devices. Such enhanced properties are attributed to the induced normal ferroelectric state in AN–based solid solutions. The crystal structural analysis of 0.80AN-0.20KNN confirms that the initial centrosymmetric and nonpolar phase (Pbcm) of AN has been transformed into a non-centrosymmetric and polar symmetry Pbc21.