Effect Of Spark Plasma Sintering Pressure On The Crystal Structure And Properties Of PZT And PLZT Ceramics

PZT piezoelectric ceramics and PLZT photoelectric functional ceramics are widely used in electronic industy,military and national defense,which medical treatment and other fields because of their excellent performance,strong anti-interference ability and low cost.Although lead-based ferroelectric materials have excellent properties,they all have the problem of volatile Pb O at high-temperature during the preparation process.Therefore,researchers are eager to find a sintering method with low sintering temperature and fast preparation speed from the root cause to solve the problem of lead oxide voatilization of lead-based ferroelectric materials.Spark plasma sintering（SPS）technology as a typical representative of rapid low-temperature sintering,which starts received extensive attention from researchers.The study found that its special sintering mechanism and low-temperature rapid sintering method for ferroelectric material of the preparation of cationic volatile has a unique advantage.SPS technology can also provide a uniaxial pressure in the sintering process,which plays an important role in improving the density of materials and regulating the microstructure.However,at this stage,the sintering pressure of SPS is mainly used to improve the dense material,and the relationship between sintering pressure and material structure and properties needs further study.In this experiment,PZT piezoelectric ceramics and PLZT photoelectric functional ceramics near the morphotropic phase boundary（MPB）were prepared by spark plasma sintering at different pressures（10 MPa,20 MPa,30 MPa,40 MPa）.The effect of sintering pressure by SPS on the structure and properties of the material was studied.Through Rietveld refinement results,it was found that changing the sintering pressure distorted the crystal structure of the sample.XPS was uesd to study the chemical states of Pb,La,Zr and Ti elements in PZT/PLZT ceramics,and Raman spectroscopy was used to study the changes of chemical bonds in the material.The law of crystal structure change is consistent with the law of performance change,so we make the following summary of the relationship between pressure,structure and performance:1.Compared with the PZT/PLZT ceramics prepared by solid-phase sintering,the rapid and low-temperature sintering method of spark plasma sintering can reduce the volatilization of lead oxide,ensures the accuracy of stoichiometric ratio,and inhibit the grain growth,which is conducive to improving the mechanical and electrical properties of materials.2.During the preparation of PZT ceramics,the sintering pressure of SPS can not only improve the density of the material,but also the sintering pressure changed the chemical valence state of titanium and promoted the transformation of rhombohedral to tetragonal phase.In the preparation process of PLZT ceramics,the sintering pressure causes lattice distortion by affecting the content of doping elements,which in turn affects the properties of PLZT ceramics.3.When spark plasma sintering was used and the sintering pressure was controlled to be30MPa,PZT piezoelectric ceramics and PLZT photoelectric functional ceramics with the best performance will be obtained.PZT ceramics spontaneous polarization to P_s=75.265μC/cm² and piezoelectric constant d₃₃=136.9 p C/N.The remnant polarization of PLZT ceramics reaches Pr=70.763μC/cm²,which is 1.6 times that of the solid-phase sintered samples,and has the highest photoluminescence performance.