PHASE-EQUILIBRIA IN THE SYSTEM YPO4-NA4P2O7-NAPO3

Phase equilibria in the part of the ternary system Y2O3-Na2O-P2O5, whi ch contains the composition range YPO4-Na4P2O7-NaPO3, have been examin ed and determined by differential thermal analysis and X-ray powder di ffraction. The partial system YPO4-Na4P2O7-NaPO3 is surrounded by thre e side binary systems, whose phase diagrams are known. In two of these side systems, there are intermediate compounds with the formulae Na5P 3O10 and Na2YP3O10. It was discovered that in the partial system YPO4- Na4P2O7-NaPO3 under investigation there are two sections. Their phase diagrams have been determined as well.