Relaxor or classical ferroelectric behavior in A site substituted perovskite type Ba_1–<i>x</i>(Sm_0.5Na_0.5)_<i>x</i>TiO₃

Abstract

Abstract New ferroelectric ceramics of ABO 3 perovskite type were synthesized in the Ba 1– x (Sm 0.5 Na 0.5 ) x TiO 3 system by solid state reaction technique. The effect of the replacement of barium by samarium and sodium in the A cationic site on structural and physical properties was investigated. These compounds crystallize with tetragonal or cubic symmetry. The material is classical ferroelectric for 0 ≤ x ≤ 0.1 and 0.5 ≤ x ≤ 0.6, and present a relaxor behavior for 0.2 ≤ x ≤ 0.4. The dielectric behavior depends upon the cationic disorder in the A site and the cell size. Small rate substitution allows a ferroelectric‐paraelectric transition. For higher rate of substitution the possible random position of the Sm–Na cations brings to a relaxor sate and when the substitution rate x becomes higher than 0.5, the material comes back to a ferroelectric state due to the reduced cell size. Some of these new compositions are of interest for applications due to their physical properties and environmentally friendly character. (© 2006 WILEY‐VCH Verlag GmbH &amp; Co. KGaA, Weinheim)