Molten lithium carbonate–sodium carbonate–potassium carbonate eutectic: electronic spectroscopy of first-row transition metal compounds

Abstract

Stable solutions containing chromate(vi), cobalt(ii), nickel(ii), and copper(ii) have been obtained at 420 "C in a molten lithium carbonate-sodium carbonate-potassium carbonate eutectic. Electronic spectroscopy has demonstrated the existence of the tetrahedral chromate(vi) in the melt while nickel(i1) and copper(ii) exhibited six-fold co-ordination by oxygen, the nickel(ii) species appearing to change to a more symmetrical octahedral co-ordination on solidification. The cobalt( ii) geometry can be interpreted as octahedral or dodecahedral. While chromate(vi) dissolved readily in the melt without apparent decomposition, attempts to prepare more concentrated solutions ( >0.01 mol kg-l) of the acidic cobalt(ii), nickel(ii), or copper(ii) cations resulted in the precipitation of the respective metal oxide due to acid-base reactions with the carbonate ion.

Low energy synthesis of cement compounds in molten salt

“…For the synthesis of oxides, the initial reactant may consist of a salt such as carbonate, sulphate or chloride,17 or even the oxide itself 18. Mixed oxides may be prepared using precursors such as oxides, chlorides, oxychlorides or sulphates 11,19 – 21…”