EFFECTS OF ION Cr3+ CONCENTRATION ON THE OPTICAL PROPERTIES OF ZnAl2O4:Mn2+ PHOSPHOR POWDER VIA SOL-GEL METHOD
Abstract
Green and red emitting co-doped Mn2+ and Cr3+ ions ZnAl2O4 phosphor powders were successfully manufactured via sol-gel method combined with air annealing at different temperatures. The results of X-ray diffraction show that the ZnAl2O4 material has the best crystal quality when heated at 1400 oC. FE-SEM imaging results show that the powder with particle size increases as the sintering temperature increases, at a temperature of 1400 oC the particle size is distributed from several tens of nanometers to hundred nanometers. The results of the fluorescence spectra showed that the material emitted strongly in the reddish-red area and a weak emission in the green light. Weak emission with peak fluorescence at 511 nm is attributed to the transition of Mn2 + ions from the state of 4T1 → 6A1 in ZnAl2O4host. Strong emission in red and far red-light region at 686 nm emission peak due to the energy transfer of Ce3+ ions from 2T2g ®4A2g in ZnAl2O4 crystal lattice. Fluorescence excitation spectra with a peak of 686 nm showed that the material is most strongly absorbed at the excitation wavelengths of 395 nm and 535 nm corresponding to the transfer of energy of Cr3+ ions from the 4A2g ground state to the excited states of 4T1g and 4T2g. The best emitting phosphor is the 0.5% Mn2+ and 0.5% Cr3+ ions doped ZnAl2O4 sample sintered for 2 hours, at 1400 oC in air conditions.
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Published
2019-10-22
Section
NATURAL SCIENCE – ENGINEERING – TECHNOLOGY