WWW-Messbauer.Last Reviews
   WWW-Messbauer ABOUT WHAT'S NEW LAST REVIEWS

  WWW-Messbauer >> Last Reviews


Next · Previous

omparative analysis of Messbauer spectra of two natural Sapphirines. Local fields in Ca-Na-Fe pyroxene structures, Sapphirine and Surimanite.


1. omparative analysis of Messbauer spectra of two natural Sapphirines.

The comparative analysis of two Sapphirine spectra (by subtraction) shows, that the Fe2+ doublet with the greatest value of quadrupole splitting (M1a) has the relatively higher intensity in the first spectrum (Saph-A). The complex nature of the Fe3+ spectrum is to be proposed - two Fe3+ doublets could, apparently, to approximate it.







2. Local fields in Ca-Na-Fe pyroxene structures, Sapphirine and Surimanite.

The HFS parameters of two doublets in Sapphirine spectra permit us to refer them to two types of M1 polyhedra, typical to the Ca-Fe clinopyroxenes (C2/c). Early for Ge analogs of these clinopyroxenes were determined [Novikov, 2004] two distinct electron structures of Fe 2+ in the Ca-Fe clinopyroxenes (doublets M1 and M1a). The third doublet with the lowest value of guadrupole splitting belongs, apparently, to the Fe 2+ ions in the most deformed cation polyhedra, which are specific for the M2 position of pyroxene structure.

The data on Sapphirines support the idea on important role of distinct M1-M2-T configurations at changing of structural modification of pyroxene, which is attended by the processes of mutual ordering of M1 and M2 cations. This idea was discussed recently at general analysis of data on local structure of Omphacite and Jadeite [Novikov, 2007].