Study On The High-field Effect Of PMS-PZT Piezoelectric Ceramics Applied In High-power Underwater Acoustic Transducer

With the development of modern marine technologies,the development of better performance underwater acoustic transducers is of great significance.Among them,high-power piezoelectric ceramics have attracted much attention and are often used as key materials for piezoelectric ceramics in underwater acoustic transducers.In order to meet the needs of modern transducers,reduce high-field losses and high-field nonlinearities,it is important to use a variety of methods to suppress irreversible domain wall motion while maintaining good piezoelectric performance.So for this issue,the main work and results of this paper are as follows:In this thesis,we first studied the effects of substitution of sodium ions and co-doping of rare earth elements and iron ions on the high-field properties of Pb_0.98Sr_0.02(Mn_1/3Sb_2/3)_0.05Zr_0.48Ti_0.47O₃?PMS-PZT?piezoelectric ceramics.Among them,the substitution of a small amount of sodium ions reduces the dielectric loss tan?,improves the mechanical quality factor Q_m,and at the same time improves its piezoelectric performance.When the sintering temperature and sodium ion content are too high,the irreversible domain wall motion will increase,thereby increasing the high-field nonlinearity and high-field loss.At the sintering temperature of 1250°C and the substitution amount of sodium ions is x=0.5,the best overall performance is obtained:tan?=0.40%,Q_m=1790,?_r=1443,d₃₃=376 pC/N,K_p=0.63,Rayleigh coefficient?_?=0.48*10^-3 m/V,and the high-field dielectric loss at 500 V/mm is 2.05%.When the rare earth element is co-doped with a small amount of Fe₂O₃ doping,the loss performance is improved.When the doping amount of Fe₂O₃ is too high,the grain size and the number of pores increase,which deteriorate the dielectric loss performance.When the critical point is exceeded,the irreversible domain wall switching is greatly increased,so that the high-field dielectric loss.Ultimately,the best overall performance is obtained at a sintering temperature of 1150°C and an iron ion doping level of x=0.15:tan?=0.29%,Q_m=1500,?_r=1055,d₃₃=360 pC/N,K_p=0.61,Rayleigh coefficient?_?=0.60×10^-3 m/V,and the high-field dielectric loss at 500 V/mm is 2.76%.This paper then studied the effect of CeO₂ doping on PMS-PZT piezoelectric ceramics in NaCl-KCl molten salt system.Nanosized powders with less agglomeration and good dispersibility were synthesized by molten salt method.Doping a certain amount of CeO₂will reduce the grain size,increase the density of sintering,help to improve the high-field performance,and reduce the high-field dielectric loss and Rayleigh coefficient.Finally,the best overall performance was obtained at a CeO₂ doping of x=1:tan?=0.43%,Q_m=1272,?_r=1364,d₃₃=328 pC/N,K_p=0.58,Rayleigh coefficient?_?=0.60×10^-3 m/V,and the high-field dielectric loss at 500 V/mm is 3.13%.Finally,the effects of annealing under different atmospheres on the properties of CeO₂-doped PMS-PZT piezoelectric ceramics are studied.By annealing under oxygen and nitrogen,the doping content of CeO₂ is changed,so that the grains become smaller,the density increases,and the dielectric loss tan?decreases and the mechanical quality factor Q_m increases.Nitrogen annealing is more conducive to Rayleigh coefficient and high-field dielectric loss than oxygen annealing,but nitrogen annealing deteriorates the piezoelectric properties of the material.Finally,annealing in oxygen atmosphere,CeO₂ doping x=1 to get the best overall performance:tan?=0.43%,Q_m=1307,?_r=1277,d₃₃=447 pC/N,K_p=0.54,Rayleigh coefficient?_?=0.40×10^-3 m/V and the high-field dielectric loss at 500 V/mm is4.04%,which meet the desired goal.