Moessbauer study of paramagnetic relaxation effect in mixed crystals

The 57Fe Moessbauer spectra were measured in mixed crystals with different types of chemical bonding and crystal structure, i.e., (Fe,Al)(acac)3 (1), (Fe,Co)(acac)3 (2), K3[(Fe,Al)(ox)3].3H2O (3) and NH4(Fe,Al)(SO4)2.12H2O (4). The broadening of Moessbauer linewidth with increasing Fe3+-Fe3+ distance became less enhanced in the order: 1>2, or 3>1>4. Furthermore, it was found that the broadening of the linewidth was larger in neat tris(β-diketonato)iron(III) complexes than in (1). Based on these results, the determining factors of the paramagnetic relaxation time other than Fe3+-Fe3+ distance and temperature were examined in terms of the Moessbauer linewidth as an indicator. (author) 26 refs.; 3 figs.; 1 tab