Dy doped calcium silicates synthesized using agro-food wastes and conventional chemicals as resources: A comparative study

Abstract

Based on an earlier study, a mimic composition 38SiO₂–60CaO-0.5Dy₂O₃-0.2Na₂O–1MgO-0.1Al₂O₃-0.1TiO₂-0.1Fe₂O₃ (wt.%) are synthesized by solid-state reaction method. The structural, morphological, and optical properties of the synthesized sample presented in this study are compared with the corresponding properties of a similar sample derived from rice husk ash and eggshell powder as resources. The conventional chemicals derived sample are multi-phasic, containing β−Ca₂SiO₄, γ−Ca₂SiO₄, Ca₃Si₂O₇, and CaFeO₃ phases, and the CaO/SiO₂ ratio was believed to be affecting the room temperature stabilization of the β phase. Field emission scanning electron microscopy images showed that twinned particles, cracks, and edge dislocations were present in the synthesized sample. The presence of precipitates in the micrographs indicated that Dy ions were segregated on the surface of the sample. The optical bandgap of the samples was 3.7 eV, as calculated by diffuse reflectance spectroscopy. The photoluminescence emission spectrum contained characteristic emission peaks of the Dy³⁺ ions. Apart from these, additional peaks were observed due to the titanium ions present in the sample. Understanding the properties of calcium silicates containing multiple dopant ions is important to develop a white light-emitting diode. The properties of the mineral-derived sample are compared to those of the agro-food waste-derived similar sample.