Patent ID: 8623310

Claim:
A process for preparing a material having the formula: (M x H y ) +4 (P 2 0 7 ) −4 : where M is a cation selected from the group consisting of monovalent cations, divalent cations, and trivalent cations; H is hydrogen, P 2 O 7 is the pyrophosphate anion, and y is a number between 2.2 and 3.8; and x is a value sufficient to balance the overall charge of said compound comprising the steps of: a. mixing equal parts on a mole basis of 105-112% polyphosphoric acid and a compound having a monovalent metal cation or a divalent metal cation or a trivalent metal cation; b. heating the mixture prepared in step a.; c. mixing the heated step b. mixture.