Micro-Actuator Of Antiferroelectric Thick Films Based On Stress Of Phase Transition Induced By Direct Field

Antiferroelectric materials transform from antiferroelectric state into ferroelectric stateinduced by external electric field, accompanying by huge changes in the volume of materials.The transition caused a great transformation strain effect, and the time of phase transition isvery short. So the heterogeneous integration between antiferroelectric materials and siliconmicro-devices achieved by MEMS technology open up a new way for the rapid response andlarge displacement of micro-actuator. In this paper, the Preparation and phase transitionbehavior of (Pb,La) (Zr,Ti)O3antiferroelectric thick films were studied in details, and themicro-actuator of antiferroelectric thick films were fabricated by MEMS technology, and theresponse and implement capacity of the micro-actuator were investigation systematically,which provided experimental basis and theoretical guidance in the practical application ofnew functional devices.(Pb,La) (Zr,Ti)O3antiferroelectric thick films were prepared by sol-gel process and thethickness was about 3-5μm. The influence of sol concentration, heat treatment and annealingtemperature on the structure and dielectric properties were studied. The results show that:0.4mol/L sol concentration, multi-step cycle annealing process and 700oC annealingtemperature were suitable for preparing the antiferroelectric thick films.The temperature induced phase transitions and electric field induced phase transitionbehavior were studied. Under electric field, antiferroelectric thick films occurred the phasetransitions of antiferroelectric(AFE)-ferroelectric(FE) and FE-paraelectric(PE) with theincreasing of temperature, and the difference between temperatures of phase transformationswere increasing with electric field increasing. The temperature-dependent dielectricparameters were deconvoluted using Gaussian fit multi-peaks showed that two typical phasetransitions were discovered. The first peak is the AFE-FE phase transition and the secondpeak is the FE-PE phase transition which has been verified by C-V tests. The results show that: the phase transitions of AFE-FE and FE-PE were existed in antiferroelectric films at all timesand the difference between the two peaks increased with the electric field increasing.Micro-actuators of antiferroelectric thick films were fabricated by MEMS technology, andthe characteristics of response and implement were studied systematically. Based on laserDoppler vibrometer, the influence of the frequency sweep mode (Scan), given frequencymode (Sine), and fixed-frequency mode (Square) three ways on the mechanical properties ofthe micro-cantilever were analyzed in details; and the antiferroelectric phase switchingcharacteristics of the micro-cantilever were verified; the capacity of response and implementwere also studied. The results show that: with the beam length increasing, themicro-cantilever resonant frequency and the maximum rate of the beam decreased, and themaximum displacement increased.