Visualizing Polarization Domains in Barium Titanate

The 2012 IEEE Visualization Contest’s topic was the detection of phase transitions in ferroelectric materials—in particular, barium titanate (BaTiO3). (For more on the contest, see the sidebar.) Ferroelectric materials’ electric properties make them suitable for a variety of applications. One major application is high-permittivity capacitors. Several ferroelectric materials are promising alternatives for volatileand nonvolatile-memory devices. A dielectric material is ferroelectric if it exhibits spontaneous polarization that can be reversed by applying an external electric field. Dielectric materials that show nonlinear polarization are called paraelectrics. In all ferroelectrics, a phase transition from a paraelectric to ferroelectric state occurs when the material’s temperature decreases. The visualization of phase transitions, or polarization domains in general, is a novel research field. Sebastian Grottel and his colleagues recently showed how a combination of glyph-based visualizations and isosurfaces derived from the anisotropy can reveal metal oxides’ electrostatic properties. We used the particle data from the contest to derive a vector field indicating the material’s polarization. By combining several visualization methods, we qualitatively estimated the polarization domains’ size and spatial distribution. We also investigated the development of the material’s total volume over time and of the individual atoms’ oscillation about their ideal lattice positions. The domains’ development corresponded with that of the total volume and the atom mobility. On the basis of these observations, we estimated the phase transition’s onset. Exploratory visualization is a useful tool to gain insights into new data. So, our contest submission focused on interactive visualizations that facilitated exploratory analysis of the given dataset. We integrated our visualizations in MegaMol (www. vis.uni-stuttgart.de/megamol), a flexible framework for visualizing large, dynamic particle datasets.