A Novel Convenient Synthesis of Mixed-Valence TiIII/TiIV Double Phosphates Starting with Titanium Nitride TiN

Abstract

Abstract A new synthetic approach for the low- and mixed-valence double titanium phosphates starting with titanium nitride, TiN, and based on the controlled oxidation of a low-valent metal in the phosphate melt is presented. The reaction of the system MI 2O - P2O5 - TiN (MI = Na, K) in air (800-1050 °C) leads to loss of nitrogen, N2, and results in the formation of a number of double phosphates: KTiP2O7, K2TiniTiIV(PO4)3, KTiOPO4, NaTiP2O7, NaTi2(PO4)3 and a new mixed-valent diphosphate, NaTiIIITiIV(P2O7)2. The mixed-valent species K2TiIIITiIV(PO4)3 and NaTiIIITiIV(P2O7)2 were characterized by single crystal X-ray diffraction. The described synthetic procedure is proposed as a simple and convenient method for the preparation of lowand mixed-valent phosphate materials