Electrical Properties of Lead-Free Na1/2Bi1/2TiO3 Relaxor Ferroelectric Ceramics Doped with Hafnium or Zirconium

Abstract

Ferroelectric (Na1/2Bi1/2)TiO3 and its various solid solutions have been drawing special attention as a new candidate for their lead-based counterparts. In this study, therefore, hafnium- or zirconium-doped grain-oriented (Na1/2Bi1/2)TiO3 ceramics with < 001 >(pc) orientation were fabricated by templated grain growth method using anisotropically shaped SrTiO3 template particles. These molten salt synthesized SrTiO3 platelets were tape cast with calcined (Na1/2Bi1/2)TiO3 powders, and then sintered at 1200 degrees C for 6h. Texture fractions up to 70% have been obtained. Unipolar strains up to >0.25% were measured. Doped ceramics showed a relaxor-like ferroelectric behavior. A broad dielectric peak with a slim hysteresis loop was present for hafnium- or zirconium-doped samples. Electrostrictive coefficient of hafnium-doped (Na1/2Bi1/2)TiO3 ceramics were found to be 0.032m(4)/C-2, which is much larger than that of PMN-based electrostrictive materials. Electromechanical properties of hafnium- and zirconium-doped (Na1/2Bi1/2)TiO3 ceramics under electric bias were studied as well.