Research On Fabrication And Properties Of Doped PMN-PZT Piezoelectric Ceramics And Flexible MFC Actuators

Ceramics in PMN-PZT system with formula xPb(Mg_1/3Nb_2/3)O₃-?1-x?Pb(Zr_0.49Ti_0.51)O₃ were prepared by the conventional oxide-mixed method in this work.The phase diagram and electric properties were systematically investigated and the possible morphotropic phase boundary?MPB?were located near the PMN content of x=0.18.Then,the 0.18Pb(Mg_1/3Nb_2/3)O₃-0.82Pb(Zr_0.49Ti_0.51)O₃+x wt%Cr₂O₃ ceramics were prepared by using solid state reaction and sintering process.The phase diagram and electric properties were systematically investigated in order to determine the most appropriatecompositionofthepiezoelectricceramics.Onthisbase,0.18Pb(Mg_1/3Nb_2/3)O₃-0.82Pb(Zr_0.49Ti_0.51)O₃+0.15 wt%Cr₂O₃ ceramics were used to fabricate MFC?Macro Fiber Composite?actuators by means of cutting and filling process since it have the best comprehensive performance.The properties of the actuators influenced by the width of piezoelectric ceramic fibers and the properties of epoxy resin were investigated at last.Firstly,after analyzing the properties of ternary system piezoelectric ceramics of xPb(Mg_1/3Nb_2/3)O₃-?1-x?Pb(Zr_0.49Ti_0.51)O₃,the results show that the possible morphotropic phase boundary?MPB?of as-prepared ceramics were located near the PMN content of x=0.18,conformed by their corresponding best comprehensive properties.The properties parameters are:?_m=21280,tan?=2.02%,T_m=302 ^oC,d₃₃=556 pC/N,k_p=0.61,Q_m=90.7,E_c=10.61 kV/cm,P_r=37.28?C/cm².Secondly,the 0.18Pb(Mg_1/3Nb_2/3)O₃-0.82Pb(Zr_0.49Ti_0.51)O₃+x wt%Cr₂O₃?with x=0,0.1,0.15,0.2,0.25,0.30,0.50?ceramics were prepared by using solid state reaction and the results indicate that the composition with x=0.15 is close to the morphotropic phase boundary?MPB?.The properties parameters are:?_m=25813,tan?=1.72%,T_m=299 ^oC,d₃₃=535 pC/N,k_p=0.62,Q_m=128,E_c=13.99kV/cm,P_r=28.90?C/cm².Finally,0.18Pb(Mg_1/3Nb_2/3)O₃-0.82Pb(Zr_0.49Ti_0.51)O₃+0.15 wt%Cr₂O₃ ceramics were used to fabricate Macro Fiber Composite actuators by means of cutting and filling process.The results tell us that the field-induced strain of the actuators gradually increased with increasing of width of piezoelectric ceramic fibers,while the bending properties decreased at the same time.What's more,the epoxy resin reinforced by nmSiO₂ can significant improve the bending properties of MFC actuators.The test results show that the MFC actuators consist of piezoelectric ceramic fibers with a width of 0.4 mm and the epoxy resin reinforced by nmSiO₂ have the best comprehensive properties.This actuators not only have the great bending properties,but also have a superior field-induced strain.The average field-induced longitudinal strain is about 384,and the average field-induced transverse strain is about 216.