Dielectric properties of (NaBi(1-x)Kx)0.5Ti(1-x)NbxO3 ceramics fabricated by mechanical alloying

A/B-site complex perovskite (NaBi(1-x)Kx)(0.5)Ti(1-x)NbxO3 (also can be written: (1-2x)Na0.5Bi0.5TiO3-xK(0.5)Bi(0.5)TiO(3)-xNaNbO(3)) (x=0-0.08) lead-free piezoelectric ceramics were fabricated by mechanical alloying technique from their oxide/carbonate mixture. Phase evolvements of the mixture and the influence of x value on crystal structure and microstructure were investigated. The perovskite Na0.5Bi0.5TiO3 phase was progressively formed with passing through the intermediate Bi4Ti3O12 phases with increasing degree of mechanical activation. The Curie-Weiss law and a modified empirical expression were employed to describe the ferroelectric phase transition of (NaBi(1-x)Kx)(0.5)Ti((1-x))NbxO(3) ceramics. The results showed that (NaBi(1-x)Kx)(0.5)Ti(1-x)NbxO3 ceramics became more relaxor ferroelectric characteristic with the increase in value of x. The enhancement of relaxor characteristic may arise from structural disorder and compositional fluctuation in the crystal structure. (C) 2010 Elsevier B.V. All rights reserved.