Synthesis and piezoelectric properties of (Na_(0.5) Bi_(0.5)) TiO_3-BaTiO_3

(Na_(0.5)Bi_(0.5))_(1-x)Ba_xTiO_3 fine powders were synthesized by a citrate method. The piezoelectric properties of (Na_(0.5)Bi_(0.5))_(1-x)Ba_xTiO_3 ceramics were investigated. The results show that the mole ratio of citric acid to total metal cation content (C/M~(n+)) and pH value of precursor solution are main contributing factors to the formation of sol and gel. The fine powders with a pure perovskite structure can be obtained from the gel by calcining at 600℃. The powders synthesized by the citrate method exhibit fine morphology and high chemical homogeneity, thus enhancing the piezoelectric properties of (Na_(0.5)Bi_(0.5))_(1-x)Ba_xTiO_3 ceramics. (Na_(0.5)Bi_(0.5))_(1-x)Ba_xTiO_3 ceramics with the compositions near the morphotropic phase boundary (MPB) show superior piezoelectric properties due to the existence of more spontaneous polarization directions. A high piezoelectric constant d_(33) of 180 pC/N was obtained for (Na_(0.5)Bi_(0.5)_(1-x)Ba_xTiO_3 ceramics when x=0.06.