근자외선 LED 응용을 위한 NaY(MoO4)2:Eu3+ 형광체 연구

Abstract

W-LEDs based on phosphors have been extensively studied for next generation solid-state lighting. The phosphor converted W-LEDs, which were achieved by colour mixture of red, green, blue emission of phosphors with a near-UV LED, result in a relatively high CRI(colour rendering index). Eu3+ doped molybdates have received much attention for their efficient red emission and chemical stability. In this paper, the red phosphors NaY(MoO4)2:Eu3+ were synthesized by the sol-gel, solid-state reaction, two step solid-state reaction method and then the luminescent properties of powder phosphors were investigated at various temperatures. The structural characteristics of the samples were examined on powder X-ray diffraction with Cu Kα radiation. The surface morphologies of the powders were observed by field emission scanning electron microscopy. The excitation and emission spectra of the phosphors were recorded on a fluorimeter by using Xe arc lamp. The powder samples show the characteristic emission of Eu3+ under near-UV excitation with the Eu3+ 5D0-7F2 band(617 nm) being the prominent. A sharp and strong f-f transition peaks cover the near-UV region with maximum at 396 nm. Finally, the color coordinates(CIE 1931) were calculated from the emission spectra and then compared with the values obtained from the other phosphors.