고상 반응법으로 합성한 Y2SiO5: Eu3+, Bi3+ 적색 형광체의 발광 특성
Luminescence characterization of Eu3+ and Bi3+ co-doped in Y2SiO5 red emitting phosphor by solid state reaction method
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초록
본 연구에서는 근 자외선 및 가시광 영역에서 우수한 발광 강도를 가지는 적색 형광체를 얻기 위하여 고상 반응법으로 합성하여 Eu3+와 Bi3+가 도핑 된 Y2SiO5의 발광 특성을 관찰하였다. 근자외선 영역인 λex = 395 nm 기준으로 측정하였고, 5D0-7F2 의 에너지 천이에 의해 612 nm 영역에서 강한 peak가 발생하였다. CTS가 Eu3+-O2−에 의해 258 nm 영역 대에서 생성되었고, Bi3+가 함께 도핑 된 것은 Eu3+ -Bi3+-O2−에 상호작용에 의해 282 nm 영역대의 장파장 쪽으로 이동하였다. 350 nm~480 nm 영역 대에 7F0→5L9(364 nm),7F0→5G3(381 nm),7F0→5L6(395 nm),7F0→5D3(415 nm) and 7F0→5D2(466 nm)는 Bi3+와 Eu3+ f-f 천이에 의해 발생하였다. Bi3+의 도핑 농도가 증가 할수록 발광 강도가 증가함을 보이다가 0.125 mol 일 때 발광강도가 가장 우수하였고, Bi3+의 도핑 농도가 0.125 mol 이상 되면 발광 강도가 현저히 감소하는 것을 확인하였다.
Abstract
To enhance near UV-visible absorption region and to applied phosphor convert-white LEDs (PC-WLEDs), a red phosphor composed of Y2SiO5: Eu 3+, Bi3+ compounds was prepared by the conventional solid-state reaction. The photoluminescence (PL) shown that samples were excited by near UV light 395 nm for measurement of PL spectra.Emission spectra of samples have shown red emissions at 612 nm (5D0→7F2). The enhanced near UV~ visible excitation spectrum with a broad band centered at 258 nm and 282 nm originated in the transitions toward the charge transfer state (CTS) due to the Eu3+-Bi3+-O2−interaction. The other excitation band at 350 nm~480 nm, corresponding to the transitions 7F0→5L9 (364 nm),7F0→5G3 (381 nm),7F0→ 5L6 (395 nm),7F0→5D3 (415 nm) and 7F0→5D2 (466 nm), occurred due to enhanced the f-f transition increasing Bi3+ and Eu3+ ions. The PL intensity increased with increased as concentration of Bi3+ and the emission intensity becomes with a maximum at 0.125 mol.
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