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Infrared Absorption and Local Symmetry of WO 4 2− ‐ and MoO 4 2− Impurity Ions in KI and CsI Crystals
Author(s) -
Kondilenko I. I.,
Pasechny V. A.,
Tsyashchenko Yu. P.
Publication year - 1972
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.2220540243
Subject(s) - impurity , chemistry , ion , lattice (music) , infrared spectroscopy , infrared , crystallography , spectral line , absorption spectroscopy , absorption (acoustics) , analytical chemistry (journal) , atmospheric temperature range , materials science , physics , optics , organic chemistry , chromatography , astronomy , meteorology , acoustics , composite material
In the temperature range 120 to 800 °K and frequency range 1000 to 300 cm −1 a study has been made of the infrared absorption spectra of the impurity anions WO 4 2− ‐and MoO 4 2− ‐in KI and CsI single crystals. It is shown that W 4 2−and MOO 4 2−form neutral complexes W 4 2−· M 2+ and MoO 4 2−· M 2+ in KI lattice with cations M 2+ (Ca 2+ , Sr 2+ , Ba 2+ ) similar to the complexes SO 4 2−· M 2+ , CrO 4 2−· M 2+ and SeO 4 2−· M 2+ observed earlier in the f.c.c. lattices. Here a lowering of the local symmetry to C 2v of the impurity tetrahedrons results in the appearance of triplets in their vibration regions v 3 (A 2 ) and v 4 (F 2 ). The fine structure in the infrared spectrum of MoO 4 2−· M 2+ + KI was interpreted to be isotopic. A local symmetry of the impurity WO 4 2−and MoO 4 2−in CsI lattice was not identified unequivocally from the IR absorption spectra. The latter have doublet and quartet structure in the vibration regions v 1 (A 1 ) and v 3 (F 2 ), respectively, and depend on the impurity tetrahedrons and M 2+ cation concentration. One, probably, should assume the interstitial formation of impurities into b.c.c. lattice of CsI which results in the existence of complex anion‐cation neutral complexes of different kinds.