A New Red-Emitting La_1–xPr_xSr₂AlO₅ Phosphor Powder Prepared by Combustion Synthesis

Abstract

New red luminescent powders of La(1-x)Pr(x)Sr2AlO5 (x = 0.01 at.) were prepared by the combustion synthesis method. Microstructural properties were characterized by using X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The La(1-x)Pr(x)Sr2AlO5 X-ray diffraction pattern revealed a tetragonal phase. Morphology of the grains showed nanobars with sizes of approximately 550 nm in length. Photoluminescence, cathodoluminescence and diffuse reflectance were analyzed in detail. Photoluminescence revealed two narrow emission peaks located at lambda(em1) = 497 nm (green) and lambda(em2) = 620 nm and a single maximum excitation peak of lambda(ex) = 287 nm. The cathodoluminescence spectrum confirmed the peaks detected by photoluminescence analysis. The absorbance spectrum showed broad absorption with a maximum around lambda = 280 nm, which agrees with the maximum excitation peak detected by photoluminescence.

The Morphologies and Photoluminescence of Ce³⁺-Doped 0.5La₂O₃-2SrO-0.5Al₂O₃ Phosphors with SrF₂

“…However, while the SrF 2 flux exceed 0.4 mol, the Sr 9 (Al 6 O 18 ) phase (JCPDS No.79-1094) was found in the XRD patterns. This phase was also detected in the group of (La, Gd)Sr 2 (Al,B)O 5 :Ce [10] and La 1-x Pr x Sr 2 AlO 5 [11]. The excess SrO and Al 2 O 3 could react to form the Sr 9 (Al 6 O 18 ) compound along with the SrF 2 addition [13], it is agreed with our research works.…”

“…Recently, Ce-doped LSA:Ce yellow phosphors had been reported by Won et al [7,8], that it has good luminescence properties and could be used for white LEDs [8]. Using the LSA:Ce yellow phosphors, it was possible to fabricate white LEDs lamps with a good color rendering index (Ra=85) and high emission efficiency (higher than the YAG:Ce's) [9][10][11][12]. In this paper, LSA:Ce phosphors were successfully prepared by conventional solid-state reaction method using SrF 2 as flux.…”