FORMATION OF DOUBLE DIVALENT METAL-AMMONIUM CONDENSED PHOSPHATES IN THE NH₄PO₃ MELT

Abstract

Thermal behavior of the MO-NH₄PO₃ systems where M=Mg, Ca, Sr, Ba, Mn, Co, Ni, Cu, Zn, Cd, and Pb was studied at 300 and 400°C. General regularities of formation of double divalent metal-ammonium phosphates were established. Conditions of preparation of some known and novel binary divalent metal-ammonium phosphates, M(NH₄)2(PO₃)₄ (M=Mg, Ca, Mn, Co, Zn, and Cd), M(NH₄)₂P₄O₁₂ (M=Sr and Pb), MNH₄(PO₃)₃ (M=Mg, Co, Ni, Cu, Zn, and Pb),MNH₄P₃O₉ (M=Mg, Ca, Mn, and Cd), Ba₂NH₄(PO₃)₅, Cu₃(NH₄)₂P₈O₂₄, and Ba(MH₄)₄(PO₃)₆ were determined. Preliminary XRD studies have been performed for powder samples of Ba₂NH₄(PO₃)₅ (space group Pc,_unit cell dimensions a=8.649(1), b=7.312(1), c=13.873(2)Å; β=128.14(1)°) and Ba(NH₄)₄(PO₃)6 (space group_P31c, unit cell dimensions a=11.1911(2), c=8.9375(2)Å).