Preparation of red amorphous selenium

Claim 1

A process for producing stable red amorphous selenium containing thallium in particles of less than about 5 microns which comprises: a. adding a sufficient amount of selenious acid, and from about 10 parts per million to about 10,000 parts per million of thallium dioxide to methanol or ethanol containing not more than about 50 percent by weight water at a temperature between about -20° C. and the freezing point of the solution; and the solution containing hydrazine, the amount of hydrazine being at least stoichiometrically equivalent to the amount of selenious acid in the solution; b. then maintaining the solution between about -13° C. and -3° C. until the yellow-orange amorphous precipitate formed by the reduction of the selenious acid by the hydrazine changes to red amorphous selenium; c. then filtering the solution; and d. then washing the precipitate with methanol or ethanol and drying.