LiCl-AlCl<SUB>3</SUB>およびNaCl-AlCl<SUB>3</SUB> 2成分系の状態図

Abstract

Phase diagrams of LiCl-AlCl3 and NaCl-AlCl3 binary systems have been determined over the composition range of 0∼100 mol%AlCl3 by means of the direct observation, DTA method and X-ray analysis. The results obtained are summarized as follows:(1) The chemical compounds LiAlCl4 and NaAlCl4, were recognized at the composition of 50 mol%AlCl3, and their melting points were 416 and 427 K, respectively.(2) The two-liquid regions were observed in the composition range more than 82 mol%AlCl3 for the LiCl-AlCl3 system, and in the composition range more than 79 mol%AlCl3 for the NaCl-AlCl3 system.(3) The eutectic points were detected at the composition of 57 mol%AlCl3 and the temperature of 383 K for the LiCl-AlCl3 system, and at the composition of 60.5 mol%AlCl3 and the temperature of 381 K for the NaCl-AlCl3 system.(4) In the composition range less than 50 mol%AlCl3, the liquidus lines of each system show the high temperature as long as the content of AlCl3 increares from 0 to 40 mol% and then rapidly decrease with the increase of AlCl3 to the melting points of the chemical compounds. The tendency to maintain the high temperature is remarkable for the LiCl-AlCl3 system.(5) The chemical compounds LiAlCl4 and NaAlCl4 are known to be very stable. Therefore, the activities of the components were calculated from the phase diagrams by assuming the quasi-binary systems LiCl-LiAlCl4 and NaCl-NaAlCl4 in the composition range of 0∼50 mol%AlCl3. The activities show large positive deviations from Raoult’s law, and the smaller the cationic radius, the larger becomes the deviation.