In order to explore the high temperature stability of ceramic capacitor,we present temperatureindependent dielectric properties of 0.82[0.94Bi_(0.5)Na_(0.5)TiO_(3)-0.06BaTiO_(3)]-0.18K_(0.5)Na_(0.5)NbO_(3)(BNT-BT-18KNN)ceramics.For different sintered temperature and annealing treatment,the pseudoternary system showed aεr of 2265 at 1 kHz at 35℃with a normalized permittivity ε/ε35℃varying less than±15%from 11℃to 382℃.This pure perovskite phase with slimmer and heat proof PE loops possessed energy density of 0.616 J/cm^(3)with a tolerance of about3%in a temperature interval ranging from 20℃to 120℃,which is higher and more temperature stable than most ceramic capacitors,such as PLZST and 0.89BNT0.06BT0.05KNN.This relaxor ferroelectric(at room temperature)with parabolic bipolar strainelectric(S(E))curve showed a quite low temperature dependence of positive strain with less than±6.5%tolerance from the average value of 0.091%between 20℃and 120℃,which is also more temperature stable than the same composition Zhang et al.reported.These merits demonstrate that the newly produced BNT-BT-18KNN ceramics should be a promising candidate for the development of high-temperature capacitor and actuator materials.
We used a 100-mm diameter gas gun to investigate the output currents due to the sudden depolarization of poled Pb 0.99 [(Zr 0.90 Sn 0.10) 0.96 Ti 0.04 ] 0.98 Nb 0.02 O 3 ceramics under shock wave compression.We conducted shock wave experiments for the normal/axial mode with the polarization vector perpendicular/antiparallel to the shock vector.The shock pressure was in the range of 0.23 to 4.50 GPa.We measured the depoling currents under short-circuit,high-impedance,and breakdown conditions.Under the short-circuit condition,the dependence of the released charge on the shock pressure demonstrates the evolution of the ferroelectric-to-antiferroelectric phase transition.The onset pressure of the phase transition is between 0.23 and 0.61 GPa,and phase transition occurs completely above 1.22 GPa.The increasing load resistance decreases the released charge and increases the released energy.The results indicate that Pb[(ZrSn)Ti]NbOceramic is a good candidate for a pulsed power generator.
