**Structural Transformations in Ferroelectrics Discovered by Raman Spectroscopy** Structural Transformations in Ferroelectrics Discovered by Raman Spectroscopy

DOI: 10.5772/intechopen.72770

Kai Jiang, Liping Xu, Jinzhong Zhang, Zhigao Hu and Junhao Chu Kai Jiang, Liping Xu, Jinzhong Zhang,

Additional information is available at the end of the chapter Additional information is available at the end of the chapter

http://dx.doi.org/10.5772/intechopen.72770

Zhigao Hu and Junhao Chu

#### 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 (TC) 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 PbTiO3-Bi(Mg0.5Ti0.5) O3 (PT-BMT), SrxBa1<sup>x</sup>Nb2O6 (SBN), Pb11.5xLaxZr0.42Sn0.4Ti0.18O3 (PLZST), Bi1xLaxFe1<sup>y</sup> TiyO3 (BLFT) and (K0.5Na0.5)NbO3-0.05LiNbO3 (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 TC, 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.

Keywords: ferroelectrics, Raman spectra, vibration modes, phase transitions, Curie temperature
