Structure, ferroelectric and piezoelectric properties of (Bi1-x-yNa0.925-x-yLi0.075)0.5BaxSryTiO3 lead-free piezoelectric ceramics

Lead-free multi-component ceramics (Bi1-x-yNa0.925-x-yLi0.075)(0.5)BaxSryTiO3 have been prepared by an ordinary sintering technique and their structure and electrical properties have been Studied. All the ceramics can be well-sintered at 1100 degrees C. X-ray diffraction patterns shows that Li+, Ba2+ and Sr2+ diffuse into the Bi0.5Na0.5TiO3 lattices to form a new solid solution with a pure perovskite Structure, and a morphotropic phase boundary (MPB) is formed at 0.04 < x < 0.08. As compared to pure Bi0.5Na0.5TiO3 ceramic, the coercive field E-C of the ceramics decreases greatly and the remanent polarization P, of the ceramics increases significantly after the formation of the multi-component solid solution. Due to the MPB, lower E-C and higher P-r the piezoelectricity of the ceramics is greatly improved. For the ceramics with the compositions near the MPB (x = 0.04-0.08 and y = 0.02-0.04), piezoelectric coefficient d(33) = 133-193 pC/N and planar electromechanical Coupling factor k(P) = 16.2-32.1%. The depolarization temperature T-d reaches a minimum value near the MPB. The temperature dependences of the ferroelectric and dielectric properties suggest that the ceramics may contain both the polar and non-polar regions at temperatures near/above T-d. (c) 2009 Elsevier B.V. All rights reserved.