Abstract
Lead-free ceramics (1 − x)Bi 0.5Na 0.5TiO 3– xBaTiO 3 have been prepared by a conventional solid reaction method, and their structure, electrical properties and depolarization temperature have been studied. The results of X-ray diffraction reveal that Ba 2+ diffuse into the Bi 0.5Na 0.5TiO 3 lattices to form a solid solution with a pure perovskite structure, and a morphotropic phase boundary (MPB) exists at 0.06 < x < 0.10. The grain size decreases with x. After the introduction of BaTiO 3 into Bi 0.5Na 0.5TiO 3, the ceramics exhibit a lower coercive field E c and a larger remanent polarization P r. Because of the strong ferroelectricity and MPB, the ceramics with x = 0.06 exhibit optimum piezoelectric properties: d 33 = 155 pC/N and k P = 36.7%. The depolarization temperature T d shows a strong compositional dependence and gives a minimum value at MPB. In addition, the ceramics exhibit relaxor characteristic, which probably results from the cation disordering in the 12-fold coordination sites. The results of the ferroelectric and dielectric properties at high temperatures may suggest that the ceramics may contain both the polar and non-polar regions at temperatures above T d.
Published Version
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