Nanoscale Characterization of Domain Structures in Bi₄Ti₃O₁₂Single Crystals Using Near-Field Raman Spectroscopy

Abstract

We have investigated domain structures in Bi4Ti3O12 (BiT) single crystals by Raman scattering using scanning near-field optical microscopy (SNOM). In SNOM–Raman spectra, the polarization dependence reflects domain structures, and the spectra at the domain-wall region exhibit the splitting of the TiO6 mode at ∼840 cm-1 with the appearance of additional peaks, the behavior of which is different from that observed in the single-domain region. From the resonant Raman spectra of highly deficient BiT single crystals, we find that the resonance is localized at oxygen vacancies in TiO6 octahedra, and planer defects, owing to oxygen vacancies, accumulate near the domain walls, causing a strong domain pinning.

Elastic and Piezoelectric Properties of High-Quality Ferroelectric Bi4Ti3O12 Single Crystals

“…These vacancies hinder P s switching owing to large leakage current and clamping of 90 domain walls, which causes a low P r of bismuth-based ferroelectrics. [20][21][22][23][24] In addition, BiT crystals obtained by conventional methods, such as flux methods, are thin plates with a thickness of less than 0.2 mm because of a low crystal-growth rate along the c-axis. [25][26][27] The poor performance with low P r and the difficulty in growing thick crystals make the investigation of electrical properties of BiT difficult.…”