P 9391 (OTTO) Praseodymium(III, IV) oxide, 99.995% Cas no 12037-29-5 - used in pigment in glass, optic and ceramic industries. Praseodymium-doped glass, called didymium glass is used in welding, blacksmithing, and glass-blowing goggles due to its blocking property of infrared radiation. It is employed in the solid state synthesis of praseodymium molybdenum oxide, which is used as a semiconductor.