| In this paper,PZT thin films were prepared by sol-gel method,and the crystal orientation,microstructure,dielectric,ferroelectric and vibration properties of the films were characterized.The effects of heat treatment and doping on the growth of PZT thin films were studied to discuss mechanisms of PZT perovskite structure formation,preferential orientation growth and doping modification.This paper includes the following sections.(1)The effects of pyrolysis temperature and annealing temperature on the growth of PZT films were studied by fabricating PZT films with different pyrolysis temperature and annealing temperature.The results show that the pyrolysis temperature has little effect on the growth of PZT films,while the annealing temperature is the key factor affecting the formation of PZT perovskite structure and preferential orientation.The film annealed at 550°C presented pyrochlore structure,while the film annealed at 600°C exhibited dense perovskite structure with(100)preferential orientation.(2)The effects of Gd and La dopant on the growth of PZT as well as the pyrolytic film thickness on the growth of PLZT thin films were studied to disscuss the modified mechanism by doping of Gd and La.The effect of Gd doping on the growth of PZT thin films was studied by preparing and characterizing the PGZT thin films with Gd concentration from 1% to 5%.(100)-oriented PGZT thin films with dense perovskite structure were obtained when the Gd doping concentration is low,and the dielectric and ferroelectric properties of films were improved.1% Gd-doped PZT thin film obtained the largest(100)preferential orientation degree of 90.1%.2% Gd-doped PZT film obtained the maximum dielectric constant of 1310.35 at 100 Hz,which was increased by 34.2% compared with the undoped film.The maximum remanent polarization of 31.73 ?C/cm2 at 1 kHz was also obtained at 2% Gd-doped PZT film,which was 31.1% higher than the undoped film.The effects of La doping on the growth of PZT and the thickness of pyrolytic film on the growth of PLZT thin films were studied by preparing PLZT thin films with different La doping concentration and pyrolytic thickness.When the La doping concentration was low,PLZT films with thinner pyrolytic film thickness exhibited(100)preferred orientation.With the increase of the doping concentration,the films showed disordered crystalline orientation under the effect of the excess dopant and the thickness of pyrolytic film.2% La-doped PLZT thin film with thinner pyrolytic film thickness obtained the optimum dielectric properties.The dielectric constant was 1502.59 at 100 Hz,which increased by 53.9% than the undoped PZT film.2Pr of 1% La-doped PZT thin film with thicker pyrolytic film thickness reached 34.7?C/cm2,which was 9.4% higher than that of undoped film.The mechanism of Gd and La doping modification is mainly reflected in the influence of grain size and domain stability.With low doping concentration,significant donor doping effect generated lead vacancy which promote the growth of grain and improve the mobility of domain walls.With the increase of doping concentration,acceptor doping was enhanced and then created oxygen vacancy.Oxygen vacancy and excessive dopants accumulated at the grain boundary impeded the growth of grains and reduced the motility of the domain walls.(3)In the last,this paper introduced the fabrication,characterization and application of PZT piezoelectric microactuators.The PZT microactuators were fabricated by MEMS technologies,and their vibration performance was characterized by laser Doppler tester.The results show that the amplitude of the doped PZT thin films is larger than that of the undoped PZT thin film.2% La-doped PZT with thicker pyrolytic film thickness was used to drive the inkjet printhead to eject droplets. |
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