FE-57 MOSSBAUER-SPECTROSCOPY ON IRON(II) URANYL PHOSPHATE - INFLUENCE OF THE H2O MOLECULAR MOTIONS

The Mossbauer parameters of an iron(II) uranyl phosphate have been determined as a function of temperature in the range 80-300 K. The spectra were analyzed in two distinct ways, i. e. by a single ferrous quadrupole doublet and by a distribution of quadrupole splittings. In the range 225-250 K, the parameters display an anomalous variation which is ascribed to a transition from a ordered to a quasi-liquid state in the water layer on increasing the temperature. The results are compared to those obtained earlier by partly oxidized iron uranyl phosphates.