Temperature Dependence of Electric Properties of [Bi0.5(Na1-xAgx)0.5]1-yBayTiO₃ Ceramics

The temperature dependence of the piezoelectric and dielectric properties of lead-free piezoelectric ceramics, namely, [Bi 0.5 (Na 1- x Ag x ) 0.5 ] 1- y Ba y TiO 3 (abbreviated as BNBT y – x Ag, x =0–6 mol % and y =0–10 mol %), was investigated, and the features of the depolarization temperature ( T d ) of the ceramics were discussed. The temperature dependence of the piezoelectric properties shows that the piezoelectric constant ( d 33 ) decreases sharply and that the piezoelectricity almost disappears at T d for all of the ceramic samples. With an increase in the amount of Ag + , the T d of the BNBT6– x Ag ceramics decreases. Moreover, the T d of the BNBT y –4Ag ceramics decreases with an increase in the amount of Ba 2+ up to 6 mol %, and then increases with a further increase in the amount of Ba 2+ . Furthermore, the temperature dependence of the dielectric properties shows that the characteristic of the diffuse phase transition is more evident for the compositions near the morphotropic phase boundary (MPB).