Das Zustandsdiagramm des Systems KPO3?Pb(PO3)2

Phase Equilibrium Diagram of the System KPO₃? Pb(PO₃)₂ The phase equilibrium diagram of the system KPO₃? Pb(PO₃)₂ was determined by means of X-ray, DTA, paper chromatographic and hot-stage microscopic investigations. In addition to the polyphosphates of potassium KPO₃]_x and lead Pb(PO₃)₂]_x it is shown the existence of only two thermodynamically stable potassium lead phosphates: The incongruently melting cyclotriphosphate K₄PbP₃O₉]₂ and the congruently melting high-molecular polyphosphate K₂Pb(PO₃)₄]_x. The preparation of the cyclotetraphosphate K₂PbP₄O₁₂] in the pure state, obtainable by precipitation from aqueous solution, is not possible by means of thermal interaction of any starting materials.