Zustandsdiagramme von Alkalibromid-Lanthanoid(III)-bromid-Mischungen

Phase Diagrams of Alkali Bromide - Lanthanoid(III) Bromide Mixtures The phase diagrams of the systems KBr? PrBr₃ (NdBr₃, SmBr₃, GdBr₃, DyBr₃, ErBr₃, YbBr₃), RbBr? NdBr₃ (SmBr₃, GdBr₃, DyBr₃, ErBr₃, YbBr₃) and CsBr? PrBr₃ (NdBr₃, SmBr₃, GdBr₃, ErBr₃, YbBr₃) were determined by differential thermal analysis and differential scanning calorimetry. The compound M₃LnBr₆, whose stability increases with increasing size of the alkali cation resp. decreasing of the Ln³⁺ ion, was found in all investigated systems. Additionaly congruently melting compounds of the type MLn₂Br₇ were found in the system from PrBr₃ to DyBr₃ which are, however, peritectic in systems with smaller alkali cations. Another peritectic compound has the composition M₂LnBr₅, in case that the quotient ^rMe^+rX^?/^rLn³⁺ exceeds 3 this composition shifts to M₃Ln₂Br₉. The compounds M₃LnBr₆ have a transition with a transition temperature, which is concentration dependent. This May indicate that at the composition ?M₃LnBr₆”? in fact two compounds exist with slightly different composition, of which one is stable at higher the other at lower temperatures.