Present work is a part of thermodynamic research program on the MX−LnX3 system (M=alkali metal,X=Cl, Br andLn=lanthanide). Molar enthalpies of mixing in the LiBr−NdBr3, NaBr−NdBr3 and KBr−NdBr3 liquid binary systems have been determined at temperature 1063 K by direct calorimetry in the whole range of composition.
Investigated systems are generally characterized by negative enthalpies of mixing with minimum atXNdBr3≈0.3–0.4. These enthalpies decrease with decrease of ionic radii of alkali metals.
Molar enthalpies of solid-solid and solid-liquid phase transitions of K3NdBr6 and Cs3NdBr6 have been also determined by differential scanning calorimetry (DSC). K3NdBr6 is formed at 689 K from KBr and K2NdBr5 with enthalpy of 44.0 kJ·mol−1 whereas Cs3NdBr6 is stable at ambient temperature and undergoes phase transition in the solid state at 731 K with enthalpy of 8.8 kJ·mol−1. Enthalpies of melting have been also determined.