Preparation And Application Of Lanthanum Doped Lead Zirconate Titanate Ceramics

Microstructure evolutions and electrical properties of Pb_1-xLa_x(Zr_0.56Ti_0.44)_1-x/4O₃ (x=0.02, 0.04, 0.06, 0.08, 0.10, 0.12, 0.125) ceramics with the La content increasing have been investigated, because these compositions are across the morphotropic phase boundary (MBP) area in the phase diagram of the PLZT solid-solution system. This research explains the influence of La content changing on the microstructure evolutions of the PLZT traversing the chemistry compositions of the morphotropic phase boundary (MBP), and establishes the relationships between microstructure evolutions and electrical properties of the PLZT. The high quality samples 4/56/44PLZT which were prepared by a conventional mixed oxide method followed by burying sintering in PbZrO₃ powder under air atmosphere have been obtained. Furthermore, Fe³⁺ modified PLZT ceramics were prepared and characterized. Fe³⁺ ions can compensate the electric charges produced by the crystal lattice aberration, which makes the size of the PLZT ceramics grains smaller and the structure more compact. Otherwise, making use of the characteristic of the PLZT ceramics of the MBP compositions which can change photic energy to electrical energy, this paper carries through the theory investigation of the application technology, hence model of the photoelectric micro-motor has been founded, and the feasibility approved theoretically successfully.The high purity PbO, La₂O₃, TiO₂ and ZrO₂ were as starting powder, the research adopted the solid-reaction method to gain the PLZT raw powder. Then the PLZT raw powder were cold uniaxial pressed with a definite pressure into cylindrically shaped specimens. Then the specimens were cold isostatically pressed at high pressure. The Pb_1-XLa_x(Zr_0.56Ti_0.44)_1-x/4O₃(x=0.02, 0.04, 0.06, 0.08, 0.10, 0.12, 0.125) ceramics were synthesized using a high-temperature solid-state reaction technique. Then X-ray diffraction investigation, microstructure, dielectric properties of the ceramics are carried out. For all sets of samples the variation of La content induces changes in the physical properties. Otherwise, the mechanism of the microstructure evolutions of PLZT ceramics is discussed.The research of Fe³⁺ adopted the PLZT ceramics focused on the influences of iron element content increasing on the microstructure evolutions and dielectricproperties, including the experimental parameter of sinter time. The results investigated that the iron element adopted in the PLZT ceramics makes an part in compensating the electric charges produced by the crystal lattice aberration and reducing the size of the grains. With the iron element content increasing to 3.6mol%, the gained samples with sintering under identical conditions (burying into PbZrCb powder, 1250°C, 2h, air atmosphere) have the highest densities and the least size of grains. On the other hand, the iron element leads to decreasing of the dielectric constant and the dielectric loss, while the iron ions compensated the electric charges produced by the crystal lattice aberration. The results indicated the perfect experimental parameter of sinter time is two hours. Under this condition, the gained ceramics have the highest densities.In addition, the other part research work focused on found of model of the photoelectric micro-motor, and the feasibility approved theoretically successfully in theory by using FEA (finite elements analysis) method.