Development of new piezoelectric ceramics with bismuth perovskites

A new solid solution, (1-x)Bi(Ni_0.5Ti_0.5)O ₃x(Pb_aBa_b)TiO₃ (a+b=1) (NTPB [100x-100a/100b])is studied. The dielectric, ferroelectric, piezoelectric and mechanical properties indicate a new group of piezoelectric ceramics. One of the end member of the solid solution, BINT(a=b=0, x=0) is a mixture of a bismuth layered structure consisting of Bi₄Ti₃O₁₂, NiO and Bi₂O ₃. When x is increased, the crystal structure changes from a mixture of bismuth layered and perovskite structures to a single phase of the perovskite structure at x=0.2-0.25, being independent of the ratio of PbTiO₃ to BaTiO₃. The crystal phase with x⩾0.25 of the solid solution is a perovskite structure. The electrical properties are mainly investigated for the specimens of the perovskite structure (x⩾0.25) with 0.02 wt% added MnCO₃. The electromechanical coupling factors k₃₃, k_t and k_p of NTPB[40-100/0]+Mn (0.02 wt%) are 0.51, 0.47 and 0.32, respectively. The mechanical bending strength of NTPB[44.5-100/0]+Mn (0.02 wt%) is about 150 MPa