Process of making amorphous silicon nitride powder

Claim 1

A process for the preparation of an amorphous silicon nitride powder, from 0.5 to 40 mol % of the silicon being replaced by at least one modifying metal selected from the group consisting of boron, aluminum, yttrium, lanthanum, titanium, zirconium, tungsten and molybdenum, which comprises: in a first step, passing ammonia into a solution of the halides of said modifying metals in an organic solvent in an amount of n-1 to n-2 equivalents of ammonia per metal equivalent, n denoting the valency of the modifying metal in said halide; in a second step, adding an initial amount of silicon halide followed by further amounts to effect complete conversion of the halides to produce a reaction product; in a third step, separating the reaction product from the solvent; and in a fourth step, heating the reaction product into an amorphous modified silicon nitride powder a temperature of at from 800° to 1000° C.