US 4,049,779 AGranted

Crystalline salt monomers for stable phosphate glasses

AssigneeAllied Chemical Corporation

InventorRichard C. Ropp

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Abstract

Precursors for the preparation of phosphate glasses are provided. Controlled preparation of the precursors in precise stoichiometric proportions enable the preparation of glasses which are stable and possess superior optical properties of an order similar to optical glasses. Suitable precursors within the contemplation of the invention are those having the formula: M(H.sub.2 PO.sub.4).sub.n wherein M is a metal ion selected from the group consisting of Al, Zn, Cd, Fe, Sn, Mn, Pb, Ni, Co, Ga, and In and the alkaline earth metals Be, Mg, Ca, Sr and Ba and wherein n has a value of 2 or 3 depending on whether M is a divalent or trivalent ion. Mixtures of these compounds may be employed, the admixture being made prior to melting stoichiometric equivalent precursor mixture. In addition, any combination of precursors containing divalent and/or trivalent cations may be selected.

Claims19

Dependent claims

A method of preparing a water soluble monobasic phosphate glass precursor having the formula:

M(H.sub.2 PO.sub.4).sub.n
wherein M is a metal ion selected from the group consisting of aluminum, zinc, cadmium, iron, tin, manganese, lead, nickel, cobalt, gallium, indium and the alkaline earth metals beryllium, magnesium, calcium, strontium and barium, and wherein n has a value of 2 or 3 depending on whether M is a divalent or trivalent ion, in essentially pure monobasic form which comprises dissolving a compound supplying said metal ion M in a controlled execess of phosphoric acid to form a stoichiometrically proportioned solution, adding a precipitating agent, effective to precipitate soluble transition metal impurities other than the selected metal ion removing formed insolubles to produce an essentially pure solution, forming a crystal product from the resulting purified solution by evaporation, and washing said crystal product substantially free of phosphoric acid to yield a stoichiometrically proportioned crystalline phosphate salt.

Dependencies are inferred from the claim text.