Blue-excited red emission of CeO2:Eu3+, Al3+ cubic phosphor: Influence of Al3+ ion doping and Judd-Ofelt theory

Abstract

In this work, a series of CeO2: 0.1 Eu3+, xAl3+ (x = 0, 0.1, 0.2, 0.3, 0.4, and 0.5 mol %) red phosphors could be efficiently excited with blue-light was successfully prepared by solid-state reaction. The X-ray diffraction confirmed the formation of a single-phase CeO2 cubic with high crystallinity. Under blue light (466 nm) excitation, the CeO2: Eu, Al phosphors showed dominant red emission of Eu3+ ions associated with 5D0 – 7F2 transition, which matched well with the commercial blue light InGaN chip. Significantly, the red emission intensity of sample co-doped with 0.3% mol Al3+ was enhanced by 8-times compared to the un-doped one. This result was caused by the presence of Al3+ ions forming oxygen vacancies and disturbing the symmetry of the host, leading to effectively enhanced red emission of the system. The enhanced red emission mechanism of the CeO2:Eu3+, Al3+ phosphors was further explained by Judd-Ofelt (J-O) theory analysis and radiative properties, including branching ratios (βr), transition probability (A), radiative lifetime (τcal), and stimulated emission cross-section (σe) of the phosphor were determined. The CeO2:0.1Eu3+, 0.3Al3+ phosphor shows intense red emission, a long lifetime (0.735 ms), and high quantum efficiency (49.46%), making it a suitable candidate as a red component for preparing low-cost WLEDs.