Reaction Mechanisms in the Formation of PZT Solid Solutions |
| |
| Authors: | S S CHANDRATREYA R M FULRATH&#; † J A PASK |
| |
| Affiliation: | Materials and Molecular Research Division, Lawrence Berkeley Laboratory and Department of Materials Science and Mineral Engineering, University of California, Berkeley, California 94720 |
| |
| Abstract: | The solid-state reactions occurring in the system PbO-TiO2-ZrO2 were investigated using constant heating rates up to 1000°C. DTA, dilatometric length changes, and XRD analysis were used for characterization. PbO and TiO2 reacted exothermally to form the product PbTiO3 with a large volume expansion between 450° and 600°C. Formation of PbZrO3 from PbO and ZrO2 occurred endothermally with a large volume expansion between 700° and 800°C. The expansion was due to reaction topology, differential molar volumes of products and reactants, and the pellet microstructure. In the formation of PZT from ternary powder mixtures, PT formed between 450° and 600°C, followed by PZT formation at >700°C with no measurable amounts of PbZrO3 formed as determined by XRD analysis. The analysis of the mechanisms indicates that the overall kinetics of homogeneous PZT solid-solution formation are determined by either the ionic transport within the perovskite lattice or the phase-boundary reactions leading to perovskite formation and not by the diffusion of Ti across PbO, which is relatively rapid. |
| |
| Keywords: | |
|
|
