Abstract
Lead-free multi-component ceramics (Bi 1− x − y Na 0.925− x − y Li 0.075) 0.5Ba x Sr y TiO 3 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 °C. X-ray diffraction patterns shows that Li +, Ba 2+ and Sr 2+ diffuse into the Bi 0.5Na 0.5TiO 3 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 Bi 0.5Na 0.5TiO 3 ceramic, the coercive field E C of the ceramics decreases greatly and the remanent polarization P r 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.
Published Version
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