The effect of oxygen deficiency on soft modes in reduced hexagonal BaTiO3-δ studied by Raman scattering

The temperature dependence of the soft-mode shows a drastic change with increase of the reduction concentration. A micro-Raman scattering has been carried out in the temperature range 100 K ∼ 222 K, where a structural phase transition occurs (T 0 ). The dependence of T 0 on the reduction shows a goo...

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Bibliographic Details
Published in:Ferroelectrics 1998-01, Vol.217 (1), p.171-177
Main Authors: Yamazaki, Yoichi, Kasahara, Masaru, Yagi, Toshirou, Akishige, Yukikuni
Format: Article
Language:English
Subjects:
critical index
hexagonal BaTiO
Keywords
oxygen vacancy
phase transition
Raman scattering
soft-mode
Online Access:Get full text
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Summary:The temperature dependence of the soft-mode shows a drastic change with increase of the reduction concentration. A micro-Raman scattering has been carried out in the temperature range 100 K ∼ 222 K, where a structural phase transition occurs (T 0 ). The dependence of T 0 on the reduction shows a good agreement with the previous result reported by electric resistivity, dielectric constant and specific heat measurements. The Raman spectra for 0 < δ < 0·020 were observed as a function of temperature. Two soft-modes were clearly observed below T 0 as in non-reduced h-BT. Critical index increases from 1/3·2 to 1/2·0 with increasing the oxygen deficiency δ from 0 to 0·020. The increase of oxygen vacancies seems to emphasize the long-range interaction adequate for the molecular field approximation.
ISSN:0015-0193
1563-5112
DOI:10.1080/00150199808015035