Speaker
Dr
Jiri Hlinka
(Institute of Physics AS CR)
Description
Pseudo-binary solid solutions of perovskites ferroelectrics are often showing either a ferroelectric transitions with a glassy dynamics or enhanced piezoelectric properties. Because of the demonstrated application potential of (1–x)Pb(Zn1/3Nb2/3)O3–xPbTiO3 and related materials, considerable research efforts are still payed to the understanding these phenomena.
The IR spectroscopy of such lead-based perovskites is relatively well understood[1], but the assignment of Raman spectra remains a rather difficult task. The Raman activity seems to originate from both the occupational ordering [2] and the ionic off-centering [3]. The weight of these effects is varying from one material to another. Morever, the inherent disorder seems to lift the strict Raman selection rules. Interestingly, the polarized Hyper-Raman scattering spectra obey the standard polarization selection rules rather well [4,5] Nevertheless, Raman scattering in relaxors shows a measurable polarization dependence and it has been argued that specific features of polarised Raman scattering can be even employed for example to probe relaxor to ferroelectric crossover [6] or to distinguish between distinct ferroelectric phases coexisting in materials with compostion close to the so-called MPB boundaries[7].
Here we shall present our recent polarized Raman scattering studies of relaxors. In the spirit of Dyproso symposium, we shall go through the basic concepts, challenges and unpublished results.
1. JH et al, Phase Transitions, 79, 41 (2006).
2. Setter N and Laulicht I, Appl. Spectrosc., 41, 526 (1987).
3. Iwata M, et al, Jpn. J. Appl. Phys., 40, 5819 (2001).
4. A. Al-Zein, et al, Phys. Rev. B, 78, 134113 (2008).
5. A. Al-Zein et al, , Phys. Rev. Lett. 105, 017601(2010).
6. Maier B et al, Phys. Rev. B, 79, 224108 (2009).
7. I. Rafalovskyi, et al, arXiv:1304.1879 (2013).
Primary author
Dr
Jiri Hlinka
(Institute of Physics AS CR)
