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Charge ordering of asymmetrical clusters in mixed‐valence molecular crystals: Mössbauer spectra
Author(s) -
Klokishner S. I.,
Gheikhman B. D.
Publication year - 1995
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.2221880205
Subject(s) - valence (chemistry) , antiferroelectricity , asymmetry , dipole , crystal (programming language) , cluster (spacecraft) , condensed matter physics , chemistry , charge ordering , spectral line , mössbauer spectroscopy , valence electron , crystallography , molecular physics , charge (physics) , electron , physics , ferroelectricity , quantum mechanics , organic chemistry , programming language , computer science , dielectric
Abstract A crystal consisting of asymmetrical d a n ‐d b n+1mixed‐valence (MV) clusters is considered. It is supposed that the cluster distortion results from the difference of crystal fields acting on centers a and b as well as from other factors providing the difference of single‐electron wave functions of centers a and b. The model accepted takes into account Heisenberg‐type and double exchange along with cluster asymmetry and intercluster dipole‐dipole interaction. Conditions of charge‐ordered phase stabilization are elucidated. Ferro‐and antiferroelectric states of crystals comprising asymmetrical MV dimers are investigated. The phase transitions in such crystals take place gradually. Computer simulation of Mössbauer spectra is carried out. The experiments of Mössbauer spectra of a series of biferrocenium derivatives performed by the Hendrickson group are qualitatively interpreted.