: D 2472 (OTTO) Dysprosium(III) acetate, tetrahydrate, 99.9% Cas 15280-55-4 - used in electronics industry as an antireflection coating in photoelectric devices. D 2472 (OTTO) Dysprosium(III) acetate, tetrahydrate, 99.9% Cas 15280-55-4 - used in dosimeters for measuring ionizing radiation.