Abstract
Cerium trivalent (Ce3+) doped YAG nano‐sized phosphors have been successfully synthesized by sol‐gel method using different annealing temperatures. The samples have been characterized by X‐ray diffraction (XRD), thermogravimetry (TG), differential scanning calorimetry (DSC) analysis, Fourier transform infrared (FTIR) spectroscopy, and steady photoluminescence (PL) spectroscopy. X‐ray diffraction analysis indicates that the pure cubic phase YAG was formed and strongly depends on the cerium content and the annealing temperature. It was found that the grain size ranges from 30 to 58 nm depending on the calcination temperature. The YAG: Ce nanophosphors showed intense, green‐yellow emission, corresponding to Ce3+ 5d1→2F5/2, 2F7/2 transitions and its photoluminescence excitation spectrum contains the two Ce3+ 4f1→5d1, 5d2 bands. The crystal filed splitting energy levels positions 5d1 and 5d2 and the emission transitions blue shift with annealing temperatures have been discussed. It was found that the Ce3+ 4f1 ground state position relative to valence band maximum of YAG host nanomaterial decreases with increasing the temperature.
Highlights
Yttrium aluminum garnet Y3Al5O12 (YAG) exists in the cubic garnet structure and has received great attentions in various fields of advanced applications because of its excellent chemical stability, good optical properties, and high temperature creep resistance [1, 2]
It was found that the grain size ranges from 30 to 58 nm depending on the calcination temperature
The yttrium aluminum garnet (YAG) structure can be doped with several rare earth ions, allowing emissions of wavelengths from the near-infrared to ultra violet
Summary
Yttrium aluminum garnet Y3Al5O12 (YAG) exists in the cubic garnet structure and has received great attentions in various fields of advanced applications because of its excellent chemical stability, good optical properties, and high temperature creep resistance [1, 2]. The most important application of the YAG:Ce powder is converting the blue light emitting diodes (LEDs) radiation into a very broad band yellow emission, which can be used as one of the most common methods for producing white light with a gallium nitridebased blue LED [6, 7]. YAG powders have been produced via solid state reaction by mixing Y2O3 and Al2O3 powders. The disadvantage of this kind of reaction was the high reaction temperature (∼1600∘C), long heating time, milling process, and difficulty to obtain a homogeneous product and to control grain size [8]. To the best of our knowledge, the luminescence properties of YAG:Ce single crystal are well known for many years ago as phosphor and scintillator, but so far the material at the nanoscale remains poorly understood
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