Quantification of polarization distribution from polarizing light microscopy images of ferroelectric single crystals

Qualification of polarization can be realized either on a macroscopic scale as an average property by P-E hysteresis measurements or on a nano/micro scale by piezoelectric force microscopy, transmission electron microscopy, scanning electron microscopy, and so on. However, visualization and qualification of polarization distribution in the micron to millimeter scale is still a challenge. Polarizing light microscopy (PLM) is often used in the study of ferroelectric domain structures mainly for domain patterns. A phenomenon called “chromatic polarization” has been observed in transparent ferroelectric crystals by using a crossed-PLM system viewed with white light, which contains rich information about local polarization distribution. In this study, an automatic full-angle light intensity detection (AFALID) algorithm combined with colorimetry is developed to analyze the distribution of nonuniform local spontaneous polarization distribution in transparent ferroelectric single crystals. Temperature-dependent spontaneous polarizations from the color analysis for PMN-0.36PT single crystals with single tetragonal domain state are in good coincidence with those extracted from temperature-dependent hysteresis loops and pyroelectric current measurements. We further apply this method to quantify the nonuniform domain distributions with nano-indentations. This non-contact and non-destructive characterization can provide fast and automatic detection of polarization distributions in ferroelectric materials.