Blue-to-Orange Tunable Luminescence from Europium Doped Yttrium--Silicon--Oxide--Nitride Phosphors

Europium-doped yttrium--silicon--oxide--nitride phosphors are synthesized by carbothermal reduction and nitridation method. The crystal structure of the phosphors changed gradually from oxide Y₂Si₂O₇ to nitride YSi₃N₅ state with increasing dosage of Si₃N₄ and carbon powder. The Y₂Si₂O₇:Eu phosphor shows a blue emission at 465nm with 300nm excitation and a characteristic red emission of Eu³⁺ at 612nm with 230nm excitation. The YSi₃N₅:Eu phosphor shows a broad emission band centred at 595nm with some sharp peaks of Eu³⁺ with 325nm excitation. The absorption of the studied phosphors increases from 450 to 700nm with an increment in nitrogen content. Blue-to-orange tunable luminescence is observed with 390nm excitation.