Volume 49 (2006)

PHOTOLUMINESCENCE AND STRUCTURAL PROPERTIES OF SOL-GEL DERIVED NANOCRYSTALLINE Zn₂SiO₄:Mn²⁺ PHOSPHORS
Pages 73-76
Corina Enache, Paul Barvinschi, Cecilia Savii, Daniela Dascalu, Ramona Radu

Abstract
Nanocrystalline manganese activated willemite phosphors obtained by sol-gel method were investigated by X-ray powder diffraction and luminescence spectroscopy. The XRD analysis has confirmed that the 1000oC annealed samples consist of willemite structure. No other phases were put in evidence. The crystallite mean diameter size was found to be ~ 40 nm. By using a 260 nm UV excitation beam, the samples have exhibited an intense luminescence emission in the green domain of visible spectrum. The band maximum, situated at 522 nm, could be assigned to the ⁴T₁(⁴G) R ⁶A₁(⁶S) electronic transitions of tetracoordinated Mn²⁺ ions. The obtained excitation spectra show a symmetric band, ranging from 240 to 280 nm. This mainly can be ascribed to charge transfer transition between divalent manganese ground state and the conduction band. The precursors nature and synthesis conditions seem to have no implications concerning the position of the emission band in the spectra. Nevertheless it was clearly observed their significant influence upon the emission intensities.