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Temperature‐dependent Raman spectra of K 0.2 Na 0.8 NbO 3 ceramics
Author(s) -
Lima R. J. C.,
Paraguassu W.,
Freire P. T. C.,
Sasaki J. M.,
Melo F. E. A.,
Mendes Filho J.,
Lanfredi S.
Publication year - 2005
Publication title -
journal of raman spectroscopy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.748
H-Index - 110
eISSN - 1097-4555
pISSN - 0377-0486
DOI - 10.1002/jrs.1262
Subject(s) - raman spectroscopy , anharmonicity , antiferroelectricity , laser linewidth , raman scattering , phase transition , phase (matter) , chemistry , ceramic , metastability , materials science , condensed matter physics , analytical chemistry (journal) , ferroelectricity , optics , physics , laser , optoelectronics , organic chemistry , chromatography , dielectric
We performed temperature‐dependent Raman scattering studies on K 0.2 Na 0.8 NbO 3 ceramics and compared the results with those for NaNbO 3 . The wavenumbers associated with NbO 6 vibrations suggest the existence of two phase transitions, as occurs with pure NaNbO 3 ceramics. Although the disorder on the Na/K site does not change either the room temperature phase of K 0.2 Na 0.8 NbO 3 or the sequence of phase transitions compared with NaNbO 3 , it changes the temperature of the lowest phase transition and strongly modifies the temperature of the antiferroelectric → new phase II phase transition. Additionally, the linewidth analysis shows that the orientational mechanism is the dominant contribution to linewidth, although the anharmonic contribution is increased, when compared with NaNbO 3 , owing to the random distribution of potassium in the sodium niobate matrix. Copyright © 2004 John Wiley & Sons, Ltd.
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