Thermal behavior of diethylenetriaminepentaacetate complexes of zirconium and hafnium studied by the Perturbed Angular Correlations technique

CECILIA Y. CHAIN; GERMÀN N. DARRIBA; ALBERTO F. PASQUEVICH

Beijing

Conferencia; 4th Joint Meeting of the International Conference on Hyperfine Interactions and the International Symposium on Nuclear Quadrupole Interactions (HFI/NQI 2012); 2012

China Institut of Atomic Energy

Polyamino carboxilate chelating agents like diethylenetriaminepentaacetic acid (DTPA) form stable complexes with many heavy metals ions, including zirconium and hafnium. Several reports that deal with the formation of such complexes in solution can be found in the literature [1] whereas few of them could be obtained in the crystalline state.             In this work the Perturbed Angular Correlation technique has been applied to investigate the thermal behavior of the complexes KHfDTPA.3H2O and KZrDTPA.3H2O. Temperatures where changes could be expected were estimated via differential scanning calorimetry and thermogravimetric analysis. Quadrupole interactions were studied as a function of hydration and dehydration treatments.             Results showed that the characteristic triclinic structure of the hydrated chelates are associated to a well defined and highly asymmetric quadrupolar frequency whereas the dehydrated forms that arise between 50 and 160ºC are characterized by higher but less asymmetric quadrupole frequencies. This difference has been explained in terms of atomic rearrangements occurring while dehydration.             The room temperature experimental results for the electric field gradients will be compared with those obtained from ab initio calculations that are underway.