The Annealing Of Lead Zirconium Titanate Thin Films
1715 WordsDec 8, 20167 Pages
This paper will focus on how the annealing of lead zirconium titanate thin films affects its various properties, including its microstructure and electrical properties. This includes examining factors such as the annealing methods, environment, temperature, hold time and heating rate. Lead zirconium titanate is important because improvements in its production will allow for major improvements the next generation of electronic sensors and storage systems.
Piezoelectric materials are a class of materials that exhibit gaining or changing polarization when a stress is applied to the material. Polarization is the separation of charges when a material is exposed to an electric field. This ability to polarize allows…show more content…
Figure 1: Perovskite Structure of PZT (Structure of PZT)
PZT is mostly used in thin film formations and is known for its high dielectric constant, meaning that PZT can store a large amount of electric charge in an electric field. This dielectric constant depends on the film’s composition, with the highest value measured around the morphotropic phase boundary. The morphotropic phase boundary is where a ferroelectric material transitions from its tetragonal and rhombohedral phases, which for PZT is around an atomic ratio of 1.00 Pb:0.52 Zr:0.48 Ti (Chen et al., 1992). PZT is made via a number of processes where a film of the desired composition is deposited on a substrate and annealed to crystallize. The film deposition can take place in different ways, including sol-gel spin coating, molecular beam epitaxy, chemical vapor deposition, pulsed laser deposition and sputtering (Chang, 1999). While these factors have an impact on the final properties of the PZT, the final annealing determines the majority of the properties.
The annealing of lead zirconate titanate is similar to annealing any other material where heating the material improves the crystallinity of the material and removes defects. For PZT this is especially important since the amorphous phase must transform into another phase before finally transforming into the desired perovskite phase. This intermediate phase is the pyrochlore phase, which