Spectroscopic Assessments of Domain Texture in Barium Titanate: I. Confocal Raman Polarization Analysis

A three-dimensional quantitative Raman analysis of ferroelectric domain orientation is presented for single-crystalline barium titanate (BaTiO₃; BT). The analysis has been developed according to basic principles of polarized/confocal Raman spectroscopy and is aimed at visualizing in three dimensions the geometrical (local) distribution of domain c -axis in the solid angle. In the first part of the paper, the relative intensity modulation of the BT Raman phonon modes has been theoretically modeled for a BT single crystal as a function of three Euler angles; then, the complete set of Raman tensor elements has been experimentally retrieved for the A _g, the B ₁, and the E _g vibrational modes of BT. The proposed polarized Raman algorithm is finally applied to the visualization of domain patterns in BT single crystal and the possibility of nondestructively visualizing domain textures in depth is shown; thus, we demonstrate that polarized Raman spectroscopy is a valuable and efficient tool for nondestructive in space assessments of domain orientation in ferroelectric materials.