Samarium doped calcium silicate derived from agro-food wastes and their structural, optical and luminescent properties

Abstract

Samarium doped calcium silicates (Ca2−xSiO4:xSm3+, (x(%) = 0.25, 0.50, 0.75, 1.00) are synthesized using cost effective natural resources such as rice husk ash and egg shell powder through solid-state reaction method. The structural, optical, and photoluminescent properties of the as-prepared samples are reported. X-ray diffraction and Rietveld refinement results confirm that monoclinic- Ca2SiO4 phase is stabilized at room temperature in agro-food waste derived phosphors. Differential thermal analysis data provides information about the phase transformations. Scanning electron microscope images show that the synthesized samples have spherical morphology. Ca2SiO4 related vibrational bands appear in the Fourier transform infrared spectrum. Optical band gap of these phosphors is found to lie in the range 3.56–3.67 eV. Agro-food wastes inherently contain titanium in trace amounts thus, the photoluminescence emission spectrum consists of bands linked to both samarium and titanium ions. Presence of titanium makes these phosphors inherently luminescent. CIE co-ordinates of these phosphors lie in the bluish-green region. These results suggest that agro-food wastes have excellent potential of being used as precursors for synthesizing visible light emitting phosphors. Moreover, present study paves the way for effectively utilizing agro-food wastes for synthesizing environment friendly and cost-effective phosphors.