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Raman spectroscopy of coexisting phases in TbP 5 O 14
Author(s) -
Chen Ting,
Scott J. F.
Publication year - 1991
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.1250220107
Subject(s) - monoclinic crystal system , raman spectroscopy , orthorhombic crystal system , brillouin spectroscopy , phase transition , brillouin zone , phase (matter) , crystallography , chemistry , spectroscopy , materials science , optics , crystal structure , brillouin scattering , condensed matter physics , physics , laser , organic chemistry , quantum mechanics
At temperatures above the monoclinic‐orthorhombic P 2 1 / c‐Pcmn phase transition at 180°C in terbium pentaphosphate, the presence of a third phase was observed spectroscopically, identified as a C 2/ c monoclinic structure. Two lines at 12 and 17 cm −1 were observed to grow in intensity as the temperature was raised from 180 to 240°C; they would be described as acoustic modes at the Brillouin zone boundary in the Pcmn phase, made Raman‐active by the doubling of the unit cell along the c ‐axis in the C 2/ c phase. The interpretation of these lines resolves a question concerning the asymmetry (‘shoulder’) of the soft optic mode at the P 2 1 / c ‐ Pcmn ferroelastic transition raised long ago.