Research Of Electromechanical Properties Of Mn-doped Pb(In_1/2Nb_1/2)O₃-Pb(Zn_1/3Nb_2/3)O₃-PbTiO₃ Piezoelectric Ceramics

Pb(In_1/2Nb_1/2)O₃-Pb(Zn_1/3Nb_2/3)O₃-PbTiO₃（PIN-PZN-PT）piezoelectric ceramics have superior comprehensive performance compared with other lead-based materials,and have high temperature stability and good piezoelectric properties.Therefore,they have been extensively studied in recent years for use in higher power conversion.However,the pyrochlore phase is easily produced during the preparation of PIN-PZN-PT piezoelectric ceramics,it is difficult to prepare pure perovskite,and it is easy to produce pyrochlore phase,which leads to greatly reduced electromechanical performance of the system.Therefore,the PIN-PZN-PT piezoelectric ceramic system is explored.The preparation process of pure perovskite phase is particularly important.Although the piezoelectric performance of PIN-PZN-PT piezoelectric ceramic system is relatively high,its mechanical quality factor Q_m is relatively low,which limits the PIN-PZN-PT piezoelectric ceramics with excellent temperature stability and piezoelectric properties.The application of high-power transducers,while hard doping can improve the electromechanical performance of the piezoelectric ceramic system,improve the mechanical quality factor of the system,just to make up for the lack of performance of the PIN-PZN-PT system.In this paper,PIN-PZN-PT piezoelectric ceramics were prepared by solid state reaction.The optimum sintering conditions of precursors such as InNbO₄ and ZnNb₂O₆were investigated.The ideal synthesis conditions of InNbO₄ were as follows:sintering temperature 1050°C,sintering time 2 hours;ZnNb₂O₆ ideal synthesis conditions:sintering temperature 900°C,sintering time 2 hours.On this basis,the ideal synthesis conditions for PIN-PZN-PT piezoelectric ceramics were as follows:calcination temperature 720°C,calcination time 3 hours,sintering temperature 1180°C,sintering time 3 hours.It was found that the addition of 2 mol%ZnO and 3 mol%PbO during the preparation process can compensate the volatilization of PbO and ZnO in the high temperature range,and prepare a pure perovskite phase.The effects of different concentrations of manganese（0 mol%-2 mol%）on the mechanical properties of the phase boundary component PIN-PZN-PT ceramics were investigated.It was found that the mechanical properties of 49PIN-21PZN-30PT were the most superior,and the mechanical quality factor Q_m was The undoped 212 is raised to 2162 at a doping concentration of 2 mol%,which is nearly 9 times higher,achieving the expected effect of electromechanical performance through hard doping,and is provided for applications in high power transducers.The influence of hard doping on the electromechanical properties of piezoelectric ceramics is very clear,but the influence law on the dielectric relaxation characteristics of the system is still unclear.Because the dielectric relaxation characteristics of PIN-PZN-PT system are not obvious,85PIN-15PT in the PIN-PT system with obvious relaxation is selected as the research object.It is found that with the increase of manganese doping concentration,the system frequency The dispersion gradually decreases,and theΔT_m（the difference between the maximum test frequency of 200 kHz and the minimum test frequency of 100 Hz）is 10°C when the undoping is reduced toΔT_m of 0°C when the manganese doping concentration is 1 mol%.However,due to the obvious diffusibility of 85PIN-15PT,manganese doping has little effect on the dispersion factor of the system.In general,hard doping reduces the dielectric relaxation characteristics of piezoelectric ceramics and provides an experimental basis for subsequent modification of piezoelectric ceramics.