Photoluminescence properties of red emitting Ba3Bi2(PO4)4:Eu3+ phosphor for WLEDs applications

Abstract

The Eu3+ activated Ba3Bi2(PO4)4 red emitting phosphors were prepared by the conventional solid state reaction method. The phase identification of the phosphors was characterized by using the powder X-ray diffraction (PXRD) patterns. The high resolution scanning electron microscopy (HRSEM) and the photoluminescence properties of Ba3Bi2(PO4)4:Eu3+ phosphors were investigated. Exciting the phosphor at 395 nm (7F0 → 5L6) or 466 nm (7F0 → 5D2) yielded emission bands at 579, 592, 611, 651 and 698 nm, attributed to the various transitions (5D0→7FJ (J = 0,1, 2, 3, and 4)) of the Eu3+ ions in the same order. The dominant emission band at 611 nm was the well known hypersensitive red emission (5D0 → 7F2). The excitation spectrum for the 611 nm emission of the optimized phosphor (for which the maximum luminescence was observed) exhibited several bands peaking at 363, 384, 395, 417 and 466 nm. The observed excitation and the emission spectra could be attributed to the characteristic intraconfigurational 4f–4f transitions of Eu3+ ions. The Judd-Ofelt (J-O) intensity parameters (Ω2 and Ω4) were determined from the emission spectra of Eu3+ ions. The luminescence lifetime measurments were made. The temperature dependent luminescence spectra of Ba3Bi2(PO4)4:Eu3+ under the excitation of 395 nm were studied. The luminescence quantum efficiency was calculated. In addition, the Commission International del`Eclairagethe (CIE) chromaticity coordinates of Ba3Bi2(PO4)4:Eu3+ phosphor was found to be located in the red region (0.6381,0.3615) when excited at 395 nm. From these results it was noted that the Eu3+ activated Ba3Bi2(PO4)4 phosphor could be used as a red emitting phosphor for the near-UV excited WLEDs.