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Ionization of Interstitial Iron Atoms in β‐Rhombohedral Boron
Author(s) -
Kuhlmann U.,
Werheit H.,
Pelloth J.,
Keune W.,
Lundström T.
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.2221870104
Subject(s) - boron , ionization , ion , trigonal crystal system , valence (chemistry) , electron , chemistry , mössbauer spectroscopy , valence electron , atomic physics , spectral line , crystallography , crystal structure , physics , organic chemistry , quantum mechanics , astronomy
Mössbauer spectra of β‐rhombohedral boron with interstitially distributed iron atoms up to 3.33 at% are presented. Taking into account that the six D sites in the unit cell are saturated by two Fe atoms, the distribution of the Fe atoms on A and D sites proved to be simply statistical. At lower Fe contents single iron atoms on A sites are ionized to Fe 3+ , while towards higher Fe contents a rapidly increasing share of Fe 2+ ions is found. On D sites the ionization of single Fe atoms is 2+, but it changes to 3+, when two Fe atoms are accommodated in the D sites of one unit cell. The isomer shift of the Mössbauer doublets yields an estimation of the electron transfer to the boron framework. Transition from p‐ to n‐type takes place, when six electrons per unit cell are transferred from the iron ions to the boron framework. This number corresponds to the sum of the unoccupied sites in the upper valence band and the possible electron traps generated by an electron–phonon interaction in the B 12 icosahedra.