Rhone-Poulenc Industries

Michel Pajot

Jean Grosbois

Laurent Seigneurin

Bernard Boudot

Gallium oxide, Ga.sub.2 O.sub.3, well adapted for the manufacture therefrom of garnets, luminophors, and the like, is prepared by (i) admixing, under stirring, a solution of a gallium salt with a base to convert said salt into gallium hydroxide, Ga(OH.sub.3 ; (ii) aging said gallium hydroxide reaction medium at elevated temperatures to effect precipitation therefrom of a gallium oxide/hydroxide fraction, GaO(OH); (iii) next filtering said gallium oxide/hydroxide fraction from said precipitation medium; (iv) drying and (v) calcining said filtered precipitate to convert same into said gallium oxide, Ga.sub.2 O.sub.3, with said oxide/hydroxide fraction (vi) being washed either before or after said filtration step (iii).

Preparation of gallium oxide

The invention relates to a new highly reactive alumina and the method of preparing it. The alumina is characterized by an amorphous structure and a specific surface of greater than 600 m.sup.2 /g. It is prepared by thermal decomposition of the double carbonate of aluminum and ammonium of the formula AlNH.sub.4 CO.sub.3 (OH).sub.2 at a temperature of between about 200.degree. and 500.degree. C. Aluminum hydroxychlorides of the formula Al.sub.2 (OH).sub.x Cl.sub.6-x can be prepared from it.

Growing community of inventors

Salindres, France

Michel Pajot