Dielectric Relaxor Properties in the System of (Na1-xKx)1/2Bi1/2TiO3 Ceramics

Abstract

Lead-free sodium–potassium–bismuth–titanate (Na1-xKx)1/2Bi1/2TiO3 was prepared by a traditional solid-state reaction method. The temperature dependences of dielectric constants and piezoelectric properties were measured. The diffuse phase transition behavior of the solid solutions with increasing potassium content was also investigated. When x is lower than 0.2, the solid solutions exhibit a first-order phase transition below the temperature corresponding to the dielectric constant maximum. The shift behavior of the dielectric constant maximum in perovskite structure materials containing titanate was related to the diffuse phase transition behavior, which is due to the ionization of oxygen vacancies. The upshift of the dielectric constant maximum with increasing content of x shows ferroelectric properties, but it's downshift shows an antiferroelectric phase transition in the (Na1-xKx)1/2Bi1/2TiO3 system.