A novel Ba 2 MgMoO 6 :Eu 3+ orange-red phosphor: Photoluminescence properties and mechanism of charge and energy transfe
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A novel Ba2MgMoO6:Eu31 orange-red phosphor was synthesized by the Pechini method and characterized by x-ray diffraction. Photoluminescence properties of BaMgMoO6:Eu31 phosphors have been represented in the excitation and emission spectra. The charge transfer (CT) band of Ba2MgMoO6 host is situated at near-ultraviolet (UV) region, whose central wave length and bandwidth are 394 and 80 nm, respectively. And it matches well the emission wave length from near-UV light emitting diodes (LEDs). The most intensive emission of 5D0 ! 7F1 (598 nm) of Eu31 in Ba2MgMoO6:Eu31 is much narrow with a full width at half-maximum less than 2 nm under excitation with either CT band or 394 nm. And a low concentration quenching occurs in Ba2MgMoO6:Eu31, and the optimal doping concentration is about 0.05. The mechanism of charge and energy transfer from Ba2MgMoO6 host to Eu31 is proposed and analyzed on the basis of its crystal structure. In a word, Ba2MgMoO6:Eu31 may be a promising orange-red component for near UV white LEDs.
I. INTRODUCTION
The attractiveness of white light-emitting diodes (LEDs), stemming from their energy savings in combination with high brightness, long operation lifetimes, and environmental protection, positions them as the prime general lighting technology for lighting, display, and scintillation applications.1–3 White LEDs, therefore, are promising candidates to substitute for the conventional solid-state lighting sources in the coming future. Phosphor-converted approach is recognized as the most common and efficient way to generate white LED devices by combining the RGB tricolor (red, green, and blue) phosphors with near-ultraviolet (near-UV) InGaN-based chips due to its high luminous efficiency, high color-rendering index, and tunable color temperature. High-performance white LEDs have been fabricated by combining blue phosphor BaMgAl 10 O17:Eu21, green phosphor ZnS:Cu1,Al 31, and red phosphor Y 2 O2 S:Eu31 with near-UV LED chip. Unfortunately, the efficiency of the red phosphor Y2O2S:Eu31 is much lower than that of the green and blue phosphors.4 In addition, this sulfide-based phosphor comes into being easily decomposed and causes poisonous gas as it contains toxic elements against strong irradiation and its lifetime is inadequate under the excitation of UV light.5,6 Recently, Eu21-doped nitrides have attracted more attention due to their high stability and high luminous efficiency. For example, Ca2 Si 5 N8:Eu21, 7 Sr 2 Si 5N8 :Eu 21,8 and a)
Address all correspondence to this author. e-mail: [email protected] DOI: 10.1557/jmr.2013.311 3130
J. Mater. Res., Vol. 28, No. 22, Nov 28, 2013
http://journals.cambridge.org
Downloaded: 13 Mar 2015
MAlSiN3:Eu21 (M 5 Ca, Sr)9 red phosphors have been developed and improved. However, almost the nitrides above have to stand critical preparation conditions, such as high temperature, high N2 pressure, and air-sensitive starting powders, etc., which restrict the widespread use of nitride red phosphors. Therefore, it is an urgent task to search for a new red phosphor with high ef
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