D 2477 (OTTO) Dysprosium(III) acetate, tetrahydrate, 99.99% Cas 15280-55-4 - used in dosimeters for measuring ionizing radiation. D 2477 (OTTO) Dysprosium(III) acetate, tetrahydrate, 99.99% Cas 15280-55-4 - used as laboratory reagent, optical glasses, structural ceramics, catalysts, electrical components and photo-optical material.