Determination of the electric field gradient tensor of Fe<sup>3+</sup> in the <i>M</i>1 site of aegirine by single crystal Mössbauer spectroscopy

The electric field gradient (EFG) tensor of the 57Fe Mössbauer nucleus is a basic physical property that is important in Mössbauer spectra measurements of a single crystal because the EFG provides a constraint on the intensity of quadrupole splitting peaks. To reveal the EFG tensor of Fe3+ in the octahedral M1 site of clinopyroxene, Mössbauer spectra of six crystallographically oriented single crystal of aegirine in thin sections were measured....