Synthesis of nanosized AlN:Eu 2+ phosphors using a metal-organic precursor method
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Simeon Agathopoulos Materials Science and Engineering Department, University of Ioannina, GR-451 10 Ioannina, Greece (Received 1 May 2014; accepted 25 August 2014)
Nanosized Eu21-doped AlN phosphor was successfully synthesized by a metal-organic precursor method for the first time. Aluminum and europium chlorides were simultaneously reacted with triethylamine in acetonitrile media to yield solid precipitates, which were transformed into nanosized AlN:Eu21 phosphor powders upon calcination in an ammonia gas atmosphere. The possible reaction mechanism was proposed, which is in good agreement with the experimental results. The direct formation of Al–N bonds through a coordination reaction in solution is a key factor in the formation of well-crystallized AlN:Eu21 grains at a moderately low temperature (1200 °C), which significantly suppresses abnormal grain growth and favors the formation of nanocrystalline (;15 nm) particles with a homogeneous particle size distribution. Due to the homogeneous distribution of a relative high amount of Eu incorporation (2 wt%), the nanophosphors were effectively excited by UV light and featured an intense green emission band with a peak at 506 nm. I. INTRODUCTION
Light-emitting diodes (LEDs) have gained increased attention in daily life because of their superior lifetime, efficiency, reliability, and low pollution effect.1–3 There are two fundamental ways to generate white light. Both methods require suitable phosphors, which refers to their ability to down-convert LED light.4,5 In recent years, newly developed (oxy)nitride phosphors have attracted the main focus of research in this field, because of their high efficiency, longer excitation and emission wavelengths, as well as their remarkable chemical and thermal stabilities.6–8 Aluminum nitride is a typical binary nitride with a wurtzite structure. It has been widely studied for electronic packing applications because of its high electrical insulation, high thermal conductivity, low thermal expansion coefficient, and high chemical stability.9,10 Aluminum nitride has been also proposed as a potential candidate for photoluminescence and electroluminescence devices due to its wide band gap (6.2 eV).11 Thus, there are many studies on AlN thin films or phosphors doped with rare-earth or transition metals.12–17
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Address all correspondence to this author. e-mail: [email protected] DOI: 10.1557/jmr.2014.265 2466
J. Mater. Res., Vol. 29, No. 20, Oct 28, 2014
http://journals.cambridge.org
Downloaded: 12 Mar 2015
The development of phosphors with controlled morphology and nanosized particles, which will make possible the achievement of high packing density and a low light scattering coefficient, is a great challenge in modern technology because it will lead to improvements in the brightness and resolution of displays. Thus, nanooxynitride phosphors can be considered as candidates in the field of luminescent labeling. Oxynitride phosphors are superior to oxides and sulfurs because they have longer excitation wavelengths, higher emission intensity
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