Preparation And Characterization Of Ferroelectric Materials In The Pt

In the first part of the dissertation, the ceramic materials of PZT have been prepared and the influence of the factors, such as doping, component, craft, etc. on the properties of ferroelectric, as well as dielectric has been researched. At the second, the lead titanate and modified lead titanate thin films have been prepared by Sol-Gel spin process. The crystal structures, surface morphologies and thicknesses of the thin films have been studied by the means of modern analysis techniques such as XRD, AFM, SEM, etc. The dielectric and ferroelectric performance have been investigated. 1. (Ca, Sr,La)doped PZT (Lead Zirconate Titanate) ceramics have been prepared by conventional solid reaction sintering. The influences of Zr/Ti ratio and annealing temperature have been studied emphatically. We found that these two factors are both key factors to influence the performances of the PZT ceramic samples. With the increase of Zr/Ti ratio, the parameters of Pr , Ps , Ec , ε,tgδpresent the trend of becoming larger basically, while the impact of different annealing temperature to the performance didn't display very obvious rule. 2. The influence of doping in lead zirconate titanate ceramics (PZT) has been studied. Effects of La³⁺ and Mn²⁺ doping on the microstructure and properties have been investigated emphatically. Comparing the ferroelectric and dielectric properties of La³⁺-doped ceramics with Mn²⁺-doped ceramics, it indicated that the La³⁺ addition increases the remnant polarization and the dissipation factor, whereas Mn²⁺ addition decreases the dissipation factor. The ceramics with good properties were obtained by La, Mn²⁺ co-doping. 3. Lead titanate thin films prepared by Sol-Gel were thermally treated by rapid thermal annealing (RTA) and conventional furnace annealing (CFA) process, respectively. The final conclusion was drawn as that: the lead titanate thin films were prepared by spin-coating precursors at 6000 rpm for 1 min and thermally treated by RTA has better dielectric and ferroelectric performance. The remnant polarization and coercive field of the sample were 6.2μC/cm2 and 3.1KV/cm, respectively. 4. The dielectric and ferroelectric performance of PLT thin films have been studied with different La concentration from 5 to 28%. It has been proved that the PLT thin films whose La concentration are 5% have better dielectric and ferroelectric performance. The remnant polarization ,coercive field,dielectric constant and tangent loss of the films are 13.8μC/cm2, 2.76KV/cm,113.6 and 1.0%, respectively. 5. (La, Ca) doped lead titanante thin films have been investigated initially. The PLCT thin films were smooth and continuous. The remanent polarization,coercive field and dielectric constant of the sample were 8.60μC/cm2, 2.53KV/cm and 562. Key words: ferroelectrics; annealing; Sol-Gel; remnant polarization; dielectric constant.