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Lattice dynamics of the phases I, II, and III of sodium hyperoxide NaO 2
Author(s) -
Brüesch P.,
Bösch M.,
Känzig W.,
Ziegler M.,
Bührer W.
Publication year - 1976
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.2220770113
Subject(s) - marcasite , raman spectroscopy , phonon , brillouin zone , ion , pyrite , chemistry , inelastic neutron scattering , phase transition , infrared spectroscopy , crystallography , lattice (music) , raman scattering , primitive cell , neutron scattering , molecular physics , condensed matter physics , scattering , crystal structure , mineralogy , physics , optics , organic chemistry , sphalerite , acoustics
The lattice vibrations of NaO 2 , single crystals in the disordered pyrite, the ordered pyrite, and the marcasite phase are studied using far‐infrared reflection spectroscopy and inelastic neutron scattering. The far‐infrared spectra of all the different phases exhibit a high‐frequency group of bands centred at about 240 cm −1 and a low‐frequency group centred at about 100 cm −1 . This similarity can be explained by the fact that the phase transitions primarily involve a mere change in the orientationsl arrangement of the O 2 −molecule ions. This leads to a relation between certain zone centre and zone boundary phonons in the corresponding Brillouin zones. The high‐frequency group corresponds in essence to the NaCl reststrahlen bands whereas the low‐frequency bands arise from the particular orientation pattern of the molecule ions demanding a primitive cell that is larger than the primitive NaCl‐type cell. The occurrence of the low‐frequency band in the disordered pyrite phase can be interpreted as a precursor effect of the transition into the ordered pyrite phase. The Raman‐ and infrared‐active phonons of the marcasite structure are analyzed on the basis of a simple short‐range force model.