Brillouin and raman spectra anomalies in knsbn with the tungsten bronze structure
作者:
I.G. Siny,
S.G. Lushnikov,
S.I. Siny,
V.H. Schmidt,
A.A. Savvinov,
R.S. Katiyar,
期刊:
Integrated Ferroelectrics
(Taylor Available online 2000)
卷期:
Volume 28,
issue 1-4
页码: 95-102
ISSN:1058-4587
年代: 2000
DOI:10.1080/10584580008222223
出版商: Taylor & Francis Group
关键词: Brillouin and Raman light scattering;ferroelectric phase transitions;relaxor ferroelectric;tungsten bronze ferroelectric
数据来源: Taylor
摘要:
The Brillouin and Raman scattering from a complex single crystal from the tungsten-bronze family, (K0.5Na0.5)0.2(Sr0.75Ba0.25)0.9Nb2O6doped with Cu2+(KNSBN:Cu), have been comparatively studied in a wide temperature range around the ferroelectric transition. Step-like anomalies in hypersonic velocity and damping confirm the first-order structural transition. These anomalies look like some perturbations on the high-temperature slopes of both a broad dip in sound velocity and a broad maximum in damping that develop in a wide temperature range. The acoustic behavior of KNSBN:Cu does not simply follow the Landau theory prediction valid for many ferroelectrics except relaxors, to which the KNSBN:Cu behavior is intrinsically analogous. The total intensity of the Raman spectra as well as the intensity of separate internal and external vibrations and their width correlate with acoustic anomalies, namely there are step-like drops at the same temperature of the first-order transition and a broad range where the intensity is drastically increased.
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