Low temperature Mossbauer spectroscopic and magnetization measurements were performed on a crystalline sample of Fe-gluconate. Fe atoms were revealed to exist in two phases i.e. a major (90-94 pct.) and a minor (6-10 pct.). Based on values of spectral parameters the former can be regarded as ferrous and the latter as ferric. A sub spectrum associated with the ferric phase shows a significant broadening below ca. 30 K corresponding to 7.5 kGs. A magnetic origin of the effect was confirmed by the magnetization measurements. Evidence on the effect of the magnetism on the lattice vibrations of Fe atoms in both components was found. The Debye temperature, T_D, associated with the vibrations of Fe2+ ions is by a factor of about 2 smaller in the temperature range below ca. 30 K than the one determined from the data measured above ca. 30 K. Interestingly, the T_D-value found for the Fe3+ ions from the data recorded below ca.30 K is about two times smaller than the corresponding value determined for the Fe2+ ions.
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