The anomalous g-factor value of paramagnetic iron centers in the topaz lattice with strong tetragonal distortion

The theoretical and experimental results of analyzing the electron paramagnetic resonance (EPR) spectra of iron impurity paramagnetic centers in the topaz (aluminum fluorosilicate) lattice are presented. Characteristic defects of the system exhibiting some lines with abnormally large values of g-factor (4.33 and 2.66) in the EPR spectra have been found. The experimental results were discussed within the framework of a previously developed model describing a defect involving an impurity iron ion replacing the Al3+ or Si4+ ion. The "Fe3+– an oxygen vacancy" model is a special case of the complexes with strong tetragonal distortion. The g-factors were calculated taking into account the covalent nature of the bonds.