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Raman spectroscopic study of phase transitions in Li 3 PO 4
Author(s) -
Popović L.,
Manoun B.,
de Waal D.,
Nieuwoudt M. K.,
Comins J. D.
Publication year - 2003
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.954
Subject(s) - raman spectroscopy , chemistry , bond length , diffraction , phase transition , valence (chemistry) , crystallography , lithium (medication) , phase (matter) , phosphate , analytical chemistry (journal) , crystal structure , thermodynamics , organic chemistry , optics , physics , medicine , endocrinology
Although three forms of lithium phosphate are known, a complete structural description of the highest temperature polymorph has not yet been given. In the present work, the phase transitions of lithium phosphate were investigated at high temperatures using Raman microscopy and x‐ray powder diffraction. Both transitions were observed by following the temperature dependence of the totally symmetrical Raman stretching vibration of PO 4 3− . Currently available structural information on the α form, resulting in P—O bond lengths of 1.787–1.899 Å, as determined by valence bond calculations, are disputed here. A correlation between Raman wavenumber and bond length in inorganic phosphates estimates the P—O bond length in α‐Li 3 PO 4 to be around 1.57(1) Å, which is in closer agreement with values for other orthophosphates of between 1.50 and 1.58 Å. Copyright © 2002 John Wiley & Sons, Ltd.