Influence of lanthanum carbonate additions on thermal stability of eutectic lithium–sodium carbonate near its melting point

Thermal behavior and stability of eutectic 52/48 Li/Na carbonate mixture containing various concentrations of lanthanum carbonate in the range 0.5–2.0 mol% was investigated by a combination of thermal analysis (DSC) and spectroscopic (EGA-FTIR) techniques under CO2 and N2 gas flows. Thermal decomposition of lanthanum carbonate with CO2 gas release was observed in the 470–480 °C range close to the melting point of eutectic alkali carbonate giving raise to formation of lanthanum oxycarbonate species. It was also found that the lanthanum carbonate phase promptly reformed, when the eutectic carbonate melt samples were cooled down to 440–460 °C under CO2 atmosphere.