PIROELECTRIC RESPONSE IN PZT CERAMICS OBTAINED FROM ACETIC ACID ROUTE USING THE SOL-GEL PROCESS

摘要

For this study, the sol-gel process and the acetic acid route was used to form dried coatings of PZT (PbZr_xTi_x)O_3 in the following compositions: 57/43, 53/47, 45/55 and 40/60 (Zr/Ti). The dried coatings were characterized by the Rays-X, electronic microscopic scanning and differential scanning calorimeter techniques. In all samples heated at 700°C the crystalline phases with PbO traces were obtained according to the phase diagrams. The crystalline phase disappeared when samples were sinterized at 900°C. Obtained samples had a polycrystalline structure with crystal sizes of 8.5 nm for the tetragonal compositions and 9.2 nm for rhombohedra compositions. Curie temperature of these materials was near to 320°C. Tablet samples prepared from dried coatings were sinterized at 900, 1000 and 1100°C. Then, samples were polished until a thickness of 500 um was obtained. Finally, to evaluate the piroelectric response, the samples were placed with Ag contacts and polarized with fields of 6 kV/mm. The composition near to the morphotropic line had the best response, for example the 53/47 sample.