A RARE-EARTH-OXIDE MATRIX FOR EMITTING PERRHENATE ANIONS

A novel ceramic-like material has been produced and tested which has t he property of emitting perrhenate anions for several thousand hours w hen heated in vacuum to temperatures between 1073 and 1173 K. Previous ly reported versions of this material were inferior to the material di scussed here, probably owing to loss of perrhenate from reduction with in the host matrix. The earlier materials, as well as the present mate rials, use barium perrhenate, a reasonably refractory compound, in a r are earth oxide matrix. The use of europium and ytterbium oxide as mat rices for barium perrhenate improves the perrhenate anion emission pro perties of these materials by an order of magnitude when compared to t he next best group of rare earth oxides. This improvement is credited to the fact that these rare earth oxides (in the +3 oxidation state) h ave stable +2 states to which they can be reduced, thereby serving as an oxidizing matrix to stabilize perrhenate. This indicates that europ ium and ytterbium +3 oxides can function as high temperature oxidizing matrices for chemical species which need to be maintained in an oxidi zed form.