Experiment Investigation Of Phase Transition Behaviors Of PZT95/5 Ferroelectric Under Thermal Shock Loading

PZT95/5 ferroelectric ceramics is the solid solution ferroelectric materials of lead zirconate titanate with a [Zr/Ti] ratio of 95:5,rich microstructures and a excellent piezoelectric,pyroelectric and ferroelectric properties.It has a high mechanical-electric transformation efficiency and releases high current,high voltage,etc.in the process of phase transformation,for which reason it has been widely used in the energy,national defense,precision instruments,etc.The phase transitions in PZT ferroelectric ceramics under the influence of temperature has been found to be the first order.The thermal hysteresis has been observed during the phase transition process.The research on the phase transition of the ferroelectric materials has been reported under the quasi-static temperature environment or slow heating only.Based on the thermal shock mechanical-thermal load testing device developed by the laboratory,This paper aimed at PZT95/5 ferroelectric ceramic mechanical and electrical response under thermal shock,the influence of mechanical-thermal load on phase transition process and the discharge process,etc.1.Based on the self-designed ferroelectric material thermal shock-force-electricity coupling test experiment platform,related test equipment commissioning work has been carried out.Stable thermal shock load parameters and heating rates has been achieved by regulating the power output in different temperature regions.Then,we have taken some electromagnetic shielding technology to solve the problem that the EMI signal produced by the rapid heating furnace have an influence on the current output signal of the sample,which ensure a workable experiment conditions for the ferroelectric material test and the electrical signal acquisition.2.The experiment on the PZT95/5 ferroelectric ceramics phase-transition process under the thermal shock has been carried out.And the current responses of the PZT95/5 ferroelectric ceramics has been obtained under different heating rates.The results indicate that the current curve appears a bimodal phenomenon,one of the peak is from 150℃ to 250℃,and the other one is from 650℃ to 1050℃,the peak respectively corresponds to the low temperature ferroelectric phase(FRL)to the high temperature ferroelectric phase(FRH)phase transition and the high temperature ferroelectric phase(FRH)to the paraelectric phase(PE)phase transition;With the increase of heating rate,phase transition temperature and the charges released from the phase transition increase,the total polarization energy has been transformed and released under the thermal shock eventually.3.The experiment has been carried out to study the PZT95/5 ferroelectric ceramics phase-transition process under the effect of mechanical-thermal coupling.The influence of external force on the PZT95/5 ferroelectric ceramics has been studied under the prepressure or the displacement constraint.The results indicate that the difference in the phase-transition feature exists in the two load ways,which reveal some influences of the mechanical loading or displacement constraints on the phase transition process and the discharge process,including the decrease of the phase transition temperature point、 an slowly increase in the current response curves,etc.