Study On Electromechanical Properties And Temperature Stability Of High Curie Temperature PYN-PZT Piezoelectric Ceramics

Piezoelectric ceramic materials can achieve efficient conversion between mechanical energy and electrical energy,and have been widely used in piezoelectric devices such as ultrasonic sensors,ultrasonic motors,and ultrasonic vibrators.With the development of science and technology,in some fields,there are higher requirements for the Curie temperature and temperature stability of piezoelectric ceramics.Based on PYN-PZT ceramics,this paper studies its electromechanical properties and temperature stability.An ultrasonic piezoelectric motor was designed and simulated by COMSOL Multiphysics software.In this paper,undoped and Mn-doped 0.1PYN-0.9PZT ceramics were prepared.Its electromechanical properties tested.The phase structure was characterized by XRD diffractometer,and the chemical reaction process of the raw materials was characterized by thermal analysis.The results show that,when Zr=47 mol%,the chemical composition of tanδ=1.66%,d₃₁=188 p C/N,k₃₁=0.36,Q_m=70,T_C=388℃.The pyrochlore phase appears in the Mn-doped ceramics.With increasing Mn content,the phase structure of material changes from trigonal phase to tetragonal phase.When Mn=0.4 wt%,the chemical composition of material d₃₁=138 p C/N,k₃₁=0.33,Q_m=490,T_C=376℃.From the perspective of the chemical reaction process,Mn ions will enter the crystal lattice in the form of trivalent after calcination,and it is likely to remain in the form of trivalent after sintering.According to the prepared materials,the temperature stability of ceramics near MPB was studied,and the slope value of temperature spectrum was used to characterize the temperature stability of ceramics.The results show that Mn doping can effectively improve the temperature stability of dielectric and piezoelectric,but not resonant frequency.The temperature stability of resonant frequency is not necessarily related to Q_m,and it is mainly affected by s^E₁₁.When the phase structure changes from tetragonal phase to rigonal phase,the slope value of the resonance frequency temperature spectrum changes from a positive value to a negative value,and the chemical composition point with a slope value close to zero is located on the side of the phase boundary near tetragonal phase.In the ceramic with a chemical composition of Mn=0.4 wt%and Zr/Ti=0.48/0.52,good resonance frequency temperature stability is obtained.In the range of-25℃to 85℃,the slope value of the resonance frequency temperature spectrum is-3 to 13Hz/℃.It can meet the application requirements of ultrasonic piezoelectric motors.Based on the application of materials,a rotating ultrasonic motor was designed,and COMSOL Multiphysics was used to analyze modal,frequency domain and steady state in the model.The simulation results show that resonance frequency is in good agreement with the theoretical calculation.With increasing length of stator,the resonance frequency decreases.For the motor designed in this paper,resonance frequency of stator is 48189 Hz.Tension increases resonance frequency of stator while pressure decreases.