Structural Transformations in Ferroelectrics Discovered by Raman Spectroscopy

Abstract

Ferroelectrics systems are of great interest from the fundamental as well as applications points, such as ferroelectric random access memories, electro-optic switches and a number of electro-optic devices. Curie temperature (T C ) is one of the important parameters of ferroelectrics for high-temperature applications. Particularly, the optical modes, which are associated with the ferroelectric to paraelectric phase transition, are of great interest. Structural transformations that alter the crystal symmetry often have a significant effect on the Raman spectroscopy. This chapter systematically studies the type ferroelectric oxides and rare earth element doped ferroelectric materials such as (KNN-LN) and so on synthesis of single crystal/ceramic and optical phonon vibration modes and the improvement of the Curie temperature characteristic using spectrometry measurements. The T C , distortion degree, and phase structure of the ferroelectric materials have been investigated by temperaturedependent Raman spectroscopy. Meanwhile, the important physical parameters exhibited a strong dependence on dopants resulting in structural modifications and performance promotion.

Sintering Aid‐Assisted Growth of 0.95(K0.5Na0.5)NbO3–0.05(Bi0.5Na0.5)(Zr0.85Sn0.15)O3 Single Crystals by the Solid‐State Crystal Growth Method and Their Characterization

“…Peaks and valleys in the intensity contour plot [indicated by the grey lines in Figure 4c,d] may indicate phase transitions or other changes. [84,91] However, the intensity changes should be accompanied by other features such as changes in mode position, full width at half maximum (FWHM), or peak intensity and FWHM ratios. To further analyze the phase transitions from the Raman spectra at different temperatures, the positions, intensities, and FWHM of the v 1 and v 2 modes versus temperature are plotted in Figure 4d.…”