Structural and optical characterization of nanoparticulate manganese doped zinc silicate phosphors prepared by sol-gel and combustion methods

The present study reports the synthesis, crystallographic structure and optical properties of manganese (Mn2+) doped zinc silicate (Zn2SiO4) nanoparticle phosphors prepared by sol-gel and combustion methods. For samples prepared by sal-gel method, the X-ray diffraction results showed phase transformation from amorphous to alpha-phase Zn2SiO4 due to annealing temperatures at 600 degrees C to 1100 degrees C, whereas for combustion samples an admixture of highly crystalline beta-phase and hexagonal wurtzite structure of ZnO was observed at annealing temperature of 600 degrees C. Photoluminescence spectra with Mn2+ concentrations ranging from 0.015-0.09 mol% were compared for two methods. Emission band assigned to the T-4(1)((4)G)->(6)A(1)(S-6) electronic transition of Mn2+ was observed with maximum intensity at similar to 573 nm for combustion samples and similar to 532 nm for sol-gel samples upon UV-excitation by a Xenon lamp. Furthermore, the photoluminescence decay curves of annealed Zn2SiO4:Mn2+ samples were observed to be bi-exponential. The fast and slow decay components are due to the pair or cluster formation and isolated ions at higher doping concentration, respectively. (C) 2016 Elsevier B.V. All rights reserved.