Synthèse, mesures des conductibilités électriques et des entropies de changements d’état pour le composé Na₂UBr₆

Electrical Conductivity of Molten Binary Ndbr3 – Alkali Bromide Mixtures

“…It is likely that this is due to an increase in the complex concentration. This observation agrees with mixing enthalpy measurements [5], that also showed that the formation enthalpy, attributed to NdBr 6 3− complex ions, increases with the ionic radius of the alkali metal cation. The alkali bromides provide additional bromide ions to enable Nd 3+ to expand its coordination shell.…”

“…These conclusions were confirmed by Raman spectroscopy investigations [18]. Octahedral NdBr 6 3− complexes were found to be predominant in MBr-rich liquid mixtures. However, increase of the NdBr 3 concentration leads to distortion of these octahedra and to polymer formation (distorted octahedra which are bridged to each other through bromide anions).…”

“…Similarly, as described above for the electrical conductivity deviations, the maximum mixing enthalpy (in absolute values) was situated at compositions of 30 -40 mol % NdBr 3 . This was ascribed to possible NdBr 6 3− complex formation. We had assumed that NdBr 6 3− anions dominate in melts of neodymium(III) bromide with alkali metal bromides (especially for systems with heavier alkali metal cations), although the existence of other complexes could not be excluded.…”

“…This was ascribed to possible NdBr 6 3− complex formation. We had assumed that NdBr 6 3− anions dominate in melts of neodymium(III) bromide with alkali metal bromides (especially for systems with heavier alkali metal cations), although the existence of other complexes could not be excluded. These conclusions were confirmed by Raman spectroscopy investigations [18].…”

“…Electrical conductivity measurements were carried out in a capillary quartz cell with cylindrical platinum electrodes as described in [6]. The cell filled with the compounds under investigation was placed into a furnace with a stainless steel block, used to [7].…”