MOLAR VOLUME AND IONIC-CONDUCTION IN MOLTEN LABR3

Prior to the measurements of physicochemical properties, bromination o f La2O3 with NH4Br was attempted to obtain LaBr3 and study the optimum condition of this reaction. The molar volumes of the molten LaBr3 wer e measured in the range 1084 to 1122 K by dilatometry and fitted as a linear function by a least-squares method. The volume change on meltin g LaBr3 was evaluated from this result and the available crystallograp hic data to be 13.6%. The conductivities of molten LaBr3 were also mea sured by an a.c. technique and fitted by a quadratic function of tempe rature in the range 1088 to 1113 K. The molar conductivities were eval uated using the data of the molar volumes and conductivities. The resu lts suggest that there exist some complexes in molten LaBr3 as well as LaCl63- in molten LaCl3.