Formation Process of Y 2 O 2 S : Eu3 + in a Preparation with Flux

The formation process of a red emitting phosphor, Y 2 O 2 S : Eu 3 + , has been clarified in a reaction Y 2 O 3 + Eu 2 O 3 + flux S + Na 2 CO 3 + K 3 PO 4 → Y 2 O 2 S : Eu 3 + + flux Sulfuration of Y 2 O 3 and Eu 2 O 3 is completed at a firing temperature as low as 700°C and at a firing period of 2h. Diffusion of Eu 3+ follows the sulfuration, and grain growth begins when lattice disorder of Y 2 O 2 S decreases to a minimum at 1050°C. Larger particles are obtained when a part of Y 2 O 3 is replaced with YPO 4 .