Preparation And Performance Control Of High Curie Point PIN-PMN-PT Transparent Piezoelectric Ceramic

Transparent piezoelectric materials couple optical functions with piezoelectric effects and provide key materials for photoacoustic imaging systems,transparent piezoelectric actuators,and transparent robots.However,the effects of grain boundaries,ferroelectric domain walls,porosity,and impurities make it a great challenge to prepare transparent piezoelectric materials with high Curie points,high transparency,and high piezoelectric coefficients simultaneously,and the potential coupling effects between the functions are still to be investigated in depth.In this paper,the effects of the solid solution ratio of the matrix,the type and doping concentration of the rare-earth elements,and the degree of Pb excess on the microstructure,phase structure,ferroelectric,piezoelectric and dielectric properties,optical transmission,electro-optical properties,and domain structure in high Curie temperature PIN-PMN-PT ternary piezoelectric ceramics were investigated.PIN-PMN-PT ceramics with high transparency,large piezoelectric coefficient,and excellent electro-optical properties were successfully prepared and applications in electro-optical modulation and energy harvesting were successfully achieved based on ceramics,verifying great potential for the design of multifunctional coupling devices.The main research is as follows:1.The effects of solid solution ratios on the structure and properties of xPIN-PMN-34PT（x=23,24,25,26,27,28 mol%）and 1.0 mol%Sm-doped y PIN-PMN-34PT（y=22,24,26,28,30 mol%）piezoelectric ceramics were investigated.The results show that the xPIN-PMN-34PT piezoceramics are all located in the morphotropic phase boundary,and the rhombohedral phase（R）content increases with increasing PIN content,with the best overall performance at 24 mol%PIN(d₃₃～630 p C/N,k_p～0.66,T_C～203°C).The highest piezoelectric coefficient of d₃₃～900 p C/N was also obtained in 1.0 mol%Sm-doped PIN-PMN-34PT ceramics with 24 mol%PIN.In addition,the 10 mol%Pb-excess sample had a higher transmittance compared to the 15 mol%Pb-excess sample.Therefore,the 24PIN-42PMN-34PT component with 10 mol%Pb excess was chosen for the next work to carry out elemental doping modification and mechanistic studies.2.The effects of Sm doping amounts（0,0.5,1.0,1.5,2.0,3.0 mol%）on the structure and properties of 24PIN-42PMN-34PT piezoelectric ceramics were investigated.The results show that the piezoelectricity,electro-optic coefficient,and transmittance of the ceramics increase and then decrease with increasing Sm doping,and the maximum piezoelectric coefficient d₃₃～905 p C/N,excellent electro-optic coefficient r_c～814 pm/V,high transmittance 63%@2500 nm and high Curie temperature T_C～179°C are obtained at1.0 mol%Sm doping simultaneously.The maximum transmittance 67%@2500 nm,piezoelectric coefficient 692 p C/N,Curie temperature 162°C,and electro-optical coefficient 406 pm/V were obtained at 2.0 mol%Sm doping.The increase in Curie temperature allows the Sm-PIN-PMN-PT ceramics to exhibit better temperature stability in terms of piezoelectric and electromechanical properties.The average size of the parallel striped domains tends to decrease and then increase,while the average size of the water striped domains tends to decrease.In addition,electro-optical modulation and energy harvesting were achieved based on ceramics,showing that Sm-PIN-PMN-PT transparent ceramics have great application prospects in the field of optical communication and medical photoacoustic imaging.3.The effects of different rare earth element doping（Eu,La,Pr,Nd）on the phase structure,microstructure,electrical as well as optical properties of PIN-PMN-PT piezoelectric ceramics were investigated.For the different Eu-doped samples,the maximum piezoelectric coefficient of 780 p C/N was obtained at 1.0 mol%Eu doping.In addition,the PIN-PMN-PT ceramics doped with 2.0 mol%Nd had the highest d₃₃～850p C/N,the largest electromechanical coupling coefficient k_p～0.62,and the highest Curie temperature T_C～159°C.This provides a probability for further improvement of the piezoelectric coefficients of this system subsequently.