Structure and ferroelectric properties of BaBi_(3.8)M _(0.2)(Ti_(3.8)Nb_(0.2))O_(15) (M=Mg, Ca, Sr and Ba) ceramics

摘要

Bismuth layer structured compounds BaBi_(3.8)M _(0.2)(Ti_(3.8)Nb_(0.2))O_(15,) with M=Mg, Ca, Sr and Ba, were synthesized through a modified chemical route. Phase and structure of the compounds were analyzed by X-ray diffraction. The structure of Mg~2 based compound was orthorhombic, while it was tetragonal for the other three compositions. Experimental results indicate that Mg~2 prefers to substitute in the Bi2O2 layer. The room temperature permittivity was maximum for Ba~2 based compound (～432). The piezoelectric coefficient was significantly enhanced in Mg ~2 based compound. The Curie temperature was found to decrease gradually in the order Mg>Ca>Sr>Ba based compound. There was a marked improvement in the relaxor behavior and remnant polarization for Ba2 based compound. The structural changes and dielectric, ferroelectric and piezoelectric properties of all the compounds was discussed and co-related.