Dynamics of Central Peaks in the Brillouin Scattering Spectra of Relaxor Ferroelectrics

2009 ◽  
Vol 421-422 ◽  
pp. 403-406
Author(s):  
Ghulam Shabbir ◽  
Seiji Kojima
Keyword(s):  
High Resolution ◽  
Temperature Dependence ◽  
Single Crystals ◽  
Brillouin Scattering ◽  
Relaxor Ferroelectrics ◽  
Relaxor Ferroelectric ◽  
Subsequent Growth ◽  
Scattering Technique ◽  
Scattering Spectra ◽  
Polar Nanoregions

High-resolution Brillouin scattering technique was applied to study the dynamics of central peaks (CPs) in two relaxor ferroelectric systems, PLZT-x/65/35 ceramics and PMN-33%PT [001] single crystals, respectively. It was found that CPs appear very close to an intermediate temperature, Td, for both type of specimens. The temperature dependence of CPs was attributed to the appearance and subsequent growth of polar nanoregions (PNRs) intrinsic to relaxor materials.

Elastic and photo-elastic constants of CH4 and CD4 obtained by Brillouin scattering

1982 ◽  
Vol 60 (3) ◽  
pp. 287-298 ◽  
Author(s):  
S. C. Rand ◽  
B. P. Stoicheff
Keyword(s):  
High Resolution ◽  
Single Crystals ◽  
Elastic Constants ◽  
Brillouin Scattering ◽  
Low Frequency ◽  
Mass Ratio ◽  
Translational Coupling ◽  
Brillouin Spectroscopy ◽  
Transverse Modes ◽  
Triple Points

The elastic constants and Pockels coefficients of CH4 and CD4 single crystals near their triple points have been determined using high-resolution Brillouin spectroscopy. For CH4 at 90.4 K, the elastic constants are C11 = 19.57 ± 0.30, C12 = 14.46 ± 0.20, C44 = 9.20 ± 0.15 kbar, and the ratios of the Pockels coefficients are p12/p11 = 1.031 ± 0.035 and p44/p11 = 0.069 ± 0.010. For CD4 at 89.2 K, C12 = 20.04 ± 0.30, C12 = 15.00 ± 0.25, C44 = 9.15 ± 0.15 kbar, and p12/p11 = 1.027 ± 0.020, P44/p11 = 0.138 ± 0.010. The velocities of the low-frequency transverse modes in CH4 and CD4 are anomalously slow in the [Formula: see text] direction, indicative of rotational–translational coupling of molecules. Isotopic differences are also evident: the Pockels coefficient p44 in CD4 is double that in CH4; and the velocities of both transverse modes in the principle directions [Formula: see text], [Formula: see text], and [Formula: see text] are in the ratio V(CH4)/V(CD4) = 1.130 instead of 1.118 as expected from the isotopic mass ratio.

Structural dependence of guided acoustic-wave Brillouin scattering spectra in hole-assisted fiber and its temperature dependence

2007 ◽  
Vol 46 (28) ◽  
pp. 6912 ◽  
Author(s):  
Takashi Matsui ◽  
Kazuhide Nakajima ◽  
Taiji Sakamoto ◽  
Kazuyuki Shiraki ◽  
Izumi Sankawa
Keyword(s):  
Acoustic Wave ◽  
Temperature Dependence ◽  
Brillouin Scattering ◽  
Structural Dependence ◽  
Scattering Spectra

PRECURSOR DYNAMICS OF Pb(B1/2B′1/2)O3-TYPE RELAXOR FERROELECTRICS STUDIED BY BROADBAND MICRO-BRILLOUIN SCATTERING

2012 ◽  
Vol 02 (02) ◽  
pp. 1241004 ◽  
Author(s):  
SEIJI KOJIMA ◽  
MUHTAR AHART ◽  
VENKATASUBRAMANIAN SIVASUBRAMANIAN ◽  
ALEXEI. A. BOKOV ◽  
ZUO-GUANG YE
Keyword(s):  
Brillouin Scattering ◽  
Central Peak ◽  
Relaxor Ferroelectrics ◽  
Polar Order ◽  
Slowing Down ◽  
Fabry Perot ◽  
A Site ◽  
Polar Nanoregions ◽  
Degree Of Order ◽  
Diffuse Phase

This paper reviews the recent progress in the understanding of the dynamics of Pb(B1/2B′1/2)O3 -type relaxor ferroelectrics using of broadband micro-Brillouin scattering spectroscopy, which covers a large frequency range from 1 to 1000 GHz by a tandem multi-pass Fabry–Perot interferometer. In contrast to Pb(B1/3B′2/3)O3 -type relaxors, there is no frustration on the B-site of perovskite structure and the degree of order of B-site cations depends on heat treatment. Remarkable softening of sound velocity and an intense central peak are observed above the Curie temperature TC owing to the polarization fluctuations in polar nanoregions (PNRs). Unlike the Pb(B1/3B′2/3)O3 relaxors, Pb(B1/2B′1/2)O3 does not undergoes a typical diffuse phase transition without lead vacancies on A-site which enhances random fields. For the (1-x) Pb ( B 1/2 B ′1/2) O 3–x PbTiO 3 solid solutions, the long range polar order increases as the PbTiO3 content increases. Nevertheless, a central peak owing to dynamic PNRs still remains even for the composition near the MPB, and a critical slowing down is clearly observed in the vicinity of TC.

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