High electromechanical coupling in relaxor Pb(Sc_1/2Nb_1/2 )O₃ - PbTiO₃ system hot-pressed piezoelectric ceramics

Dielectric and piezoelectric properties of hot-pressed Pb(Sc_1/2Nb_1/2)_0.58Ti_0.42O ₃ (PSNT 58/42) binary system are studied near the morphotropic phase boundary. High density ceramics (99.7% of the calculated value) are obtained by optimized regimes of calcining, hot pressing and annealing. Dielectric permittivity of the material at room temperature is 1600 rising to a maximum of 31000 at T_c=273°C. The value of electromechanical coupling factor k_p=70%, k_t =54% and k₃₁=48%. The value of remanent polarization is 42 μC/cm², coercive field 7 kV/cm. Annealing extended to 100 h increases the dielectric permittivity and electromechanical coupling while density decreases.