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Soft‐Mode Spectroscopy in Fe:KTa 1‐x Nb x O 3 Crystals
Author(s) -
Xia H.R.,
Li L.X.,
Wang J.Y.,
Liu Y.G.,
Wei J.Q.
Publication year - 2000
Publication title -
crystal research and technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.377
H-Index - 64
eISSN - 1521-4079
pISSN - 0232-1300
DOI - 10.1002/1521-4079(200010)35:10<1209::aid-crat1209>3.0.co;2-j
Subject(s) - soft modes , phonon , raman spectroscopy , tetragonal crystal system , ferroelectricity , phase transition , curie temperature , condensed matter physics , materials science , raman scattering , crystal structure , dielectric , chemistry , optics , crystallography , physics , optoelectronics , ferromagnetism
Fe‐doped potassium tantalite niobate, Fe:KTa 1‐x Nb x O 3 (Fe:KTN), crystallizes with x = 0.48 and a perovskite‐type structure in tetragonal system with point group 4mm, conforming space group P4mm. The paraelectric‐ferroelectric structural transition of the Fe:KTN is studied by Raman scattering investigations. A condensed soft lattice vibrational mode at the phase transition has been analyzed. It originates from the symmetric O2/O3‐Nb/Ta‐O3/O2 in‐plane bending of the Nb/TaO 6 group. The soft optical phonon mode concerns the extraordinary transverse optical phonons propagating along the [110] direction. The Raman spectra measured reflect the crystal disorder. Curie temperature measured by two methods is within 353 and 356.5 K.