Synthesis of Ca2SiO4:Dy3+ phosphors from agricultural waste for solid state lighting applications

Abstract

Trivalent dysprosium (Dy3+) ions -doped calcium silicate (Ca2SiO4) phosphors have been synthesized by utilizing agricultural waste of egg shell and rice husk through solid-state reaction method. The synthesized Ca2SiO4 powders thus obtained are crystallized in monoclinic structure with unit cell parameters of a = 5.53 Å; b = 6.67 Å; c = 9.13 Å; β = 87.43° and irregular shape morphology. Luminescent properties of Dy3+:Ca2SiO4 phosphors were studied by varying active ion concentration. The phosphors emit characteristic blue and yellow emissions of Dy3+ ions corresponding to the 4F9/2 → 6H15/2 and 4F9/2 → 6H13/2 transitions, respectively. Color coordinates evaluated from emission spectra are found to fall in the white light region. Decay curves for the 4F9/2 level of Dy3+ ions exhibit single exponential nature and turn into non-exponential with shortening of lifetime from 739 µs to 510 µs when Dy3+ ion concentration is increased from 0.001 to 0.5 mol%. All these results confirm that Ca2SiO4:Dy3+ phosphors are suitable for the use as low cost white light emitting phosphors.