Raman Scattering in (1-x)Pb(Zn_1/3Nb_2/3)O₃–xPbTiO₃ Mixed Crystal System II

Abstract

The temperature-concentration dependences of the Raman spectra in the high-temperature region above the Burns temperature and the electron diffraction at room temperature were investigated in the (1 − x)Pb(Zn 1/3 Nb 2/3 )O 3 -xPbTiO 3 mixed crystal system. It was found that in the concentration range below x = 0.8, the Raman active modes exist in the cubic phase and the intensities of the Raman lines in the cubic phase decrease with increasing temperature. A finite region where the Raman active modes are observed in the cubic phase was determined in the temperature-concentration phase diagram. On the other hand, no (1/2, 1/2, 1/2) superlattice diffraction was observed in the mixed crystal with the content above x = 0.2. The present result indicates that the Raman active modes in the high-temperature phase cannot be explained by the zone folding for the superstructure with the Fm3m symmetry.

Low-Frequency Raman Spectroscopy in Pb(Zn1/3Nb2/3)O3-PbTiO3Mixed Crystals

“…If our conjecture is in the right, the Raman scattering would become a conventional tool for the PNR, for example, the Burns temperature can be determined by the Raman scattering. Indeed, we have already reported the region in which Raman modes exist in the cubic phase on the temperature-concentration phase diagram of PZN-xPT [15]. Reported results of the IR spectrum and hyper Raman scattering in Pb(Mg 1/3 Nb 2/3 )O 3 (PMN) also seem to support our conjecture [16,17].…”

“…On the contrary, we proposed that the Raman modes in PZN-xPT arise primarily due to the polar ordering it self on the basis of experimental results of the electron diffraction and Raman scattering of the PZN-xPT system in full concentration range [15]. If our conjecture is in the right, the Raman scattering would become a conventional tool for the PNR, for example, the Burns temperature can be determined by the Raman scattering.…”

Investigations of the Cubic-Tetragonal–Orthorhombic Phase Transition Sequence in 0.5PbMg1/3Nb2/3O3–0.5PbTiO3and 0.36PbMg1/3Nb2/3O3–0.64PbTiO3Single Crystals by X-Ray, Dielectric and Raman Scattering Techniques

“…Figure 5 shows temperature evolutions of the reduced (corrected by Bose-Einstein population factor) unpolarized Raman spectra of 0.5 PMN-0.5 PT and 0.36 PMN-0.64 PT crystals. Similarly as in other complex perovskites, such as disordered PST and PIN, as well as PZN-PT [14][15][16][17][18][19], the first order Raman spectrum appears in PMN-PT single crystals within the cubic paraelectric phase. This spectrum, forbidden for Pm3m space group, originates from nanoregions of different local symmetry.…”

Light Scattering Study in Relaxor-Based Ferroelectric (1 − x)Pb(Zn1/3Nb2/3)O3-xPbTiO3

“…On the other hand, the (1/2, 1/2, 1/2) superlattice diffractions (F-spots) have been observed in PZN-xPT by electron diffraction measurement. It was reported that the chemical order structure characterized by F-spots vanished at x F ∼ 0.20 [12]. The existence of such a structure indicates an inhomogeneity of the cubic phase and should be related directly and/or indirectly to the relaxor's nature.…”