Preparation And Electric Properties Of Lead-based Titanate Ceramics

Compared with other ferroelectronic materials, lead titanate (PbTi03) has many useful properties, including a high transition temperature (-763K), a low ratio for the planar-to-thickness coupling factor, a low aging rate of the dielectric constant, and low dielectric constant. Therefore, PbTi03 shows great promise as a stable pyroelectric and piezoeletric materials for high-temperature or high-frequency applications.The advantage of hydrothermal processing is that many crystalline ceramic materials may be synthesized without a calcination step at temperature of 533K and lower. In the case of PbTi03, such low processing temperature eliminate volatilization, in addition to minimizing impurities associated with calcination and ball-milling steps.The main points:I . ReviewIn this part we have not only summarized the preparation methods of Lead-based titanate powders and ceramics, but also discussed the properties and application of the ceramics.II. Preparation and electric properties of lead titanate ceramics1. PbTi03 powders have been synthesized by suspending Ti(OC4H9)4 in aqueous solution of NaOH and Pb(COOCH3)2 3H20 at temperature ranging from 473K to 533K. Experiments show that the growth and morphology of hydrothermally derived lead titanate powders will depend strongly on the feedstock concentration, reaction time and temperature, NaOH concentration, and [Pb]/[Ti] ratio.2. PbTi03 ceramics were prepared by conventional sintering method. The effect of sinter time, temperature and atmosphere on their growth and morphology has been examined.3. The dielectric spectrum of PbTi03 ceramics has been carried out using HP4194A.III. Preparation and electric properties of modified lead titanate ceramics1. We have obtained La, Sm, Ca, Sr, Ba, and Zr-doped lead titanate powders and ceramics under the same conditions as fine PbTiO3. The influence of dopants on the size and morphology of PbTiO3 powders and ceramics has been investigated.2. The dielectric spectra of modified PbTiO3 ceramics have been measured by HP4194A. The results indicate that the dopants will change the dielectric constant and tg 8 of PbTiO3.