A Raman investigation of the ordered complex perovskite

Abstract

The complex perovskite PbMg 0.5 W 0.5 O 3 , exhibiting a long-range B-site cation ordering, has been investigated by Raman scattering from 10 K up to 956 K. The Raman results are systematically treated, and analysed through the characteristic parameters of phonon peaks. The existence of an additional intermediate phase I between the low-temperature antiferroelectric phase A and the high-temperature paraelectric phase P has been demonstrated (T AI 240 K, T IP = 312 K). These results were compared with dielectric measurements. The disappearance of the first-order Raman structures near 1000 K in the paraelectric phase is discussed in terms of dynamic disorder in the Pb and O sublattices.

Structural, dielectric and Raman scattering studies of (1−x)PbMg1/3Nb2/3O3–xPbTiO3single crystals (0 ≤ x ≤ 0.38)

“…In contrast, the low frequency modes associated with the Pb ion dynamics [12,32] exhibit non-classical, anomalous behaviour related to the increase of line widths with the temperature decreasing. Such behaviour appears in two temperature regions: in the vicinity of the structural phase transitions and below 200 K. Similar phenomenon was observed for other complex perovskites: PST, PIN and PMW [28][29][30]33] and explained by the disorder of the Pb ions. These results point to the fact that the temperature evolutions of the line widths are mainly determined by the chemical disorder in the B-sublattice and the static/or dynamic local inhomogenities related to the off-centre ion displacements correlated for different scale.…”

Ag1-xNaxNbO3(ANN) solid solutions: from disordered antiferroelectric AgNbO3to normal antiferroelectric NaNbO3

“…Consequently, the diffuse M 2 -M 3 phase transition is associated with the disordered antiferroelectric state in the ATN system [1,4]. The Raman experiments performed for the ANN solid solutions considered here showed a very similar (to ATN) temperature correlation between the appearance of the central component in the Raman spectra and the diffuse maximum of low frequency dielectric permittivity [25]. Thus, an attempt to find a link between low and high frequency phenomena seems feasible.…”

Crystallographic and dielectric properties of flux grown (B′B″: InNb, InTa, YbNb, YbTa and MgW) single crystals

“…The tan d(T) dependences exhibit two additional anomalies at 0 and À27 1C. The former seems to be related with some water contamination while the later may be connected with some structural changes indicated by Raman experiment [22].…”

“…Author carried out 96 crystal growth processes of these compounds in order to find experimentally the proper growth conditions. Obtaining of the good-quality single crystals allowed us to undertake dielectric and spectroscopic studies of PIN and PIT with different degrees of order [19][20][21] and completely ordered PYT and PMW [22,23]. Earlier PIN [15,24], PYN [25] and PYT [26] crystals were grown.…”

“…The PIT and PMW crystals were not earlier grown. In our previous papers [11,[19][20][21][22][23], some general remarks on crystal growth were given only.…”