Optical properties of heat-treated hierarchical structure of Eu3+ modified C-CaIn2O4 of small core–shell crystallites

Abstract

A natural aloe-vera gel is promptly bridging the Eu 3+ , Ca 2+ and In 3+ species in a bio-complex of a polymer network, so as it yields a sample Eu 3+ :CaIn 2 O 4 of small crystallites bonding over a grafted C-sp 2 surface layer when it is burnt in a selfpropagating combustion in air. The Eu 3+ doped C-CaIn 2 O 4 sample appears in a core-shell structure in part of the carbon forming a conjoint surface layer (shell) thereon of the individual crystallites in a hybrid nanostructure. The results are analyzed in terms of XRD patterns, phonon bands (in IR and Raman spectra), XPS bands, and hierarchical microstructure in the samples prepared with different Eu 3+ dosages in finely tuning the microstructure and optical properties as useful for an efficient phosphor, optical display system, visible lasers, energy-converters, photocatalysts, optical imaging, medical tools, and several others. A partial Eu 3+ → In 3+ doping in a crystal lattice CaIn 2 O 4 clearly reflects in a marked expansion of the lattice, as much as 2.2% found in the Eu 3+ content progressively raised to 2.0 mol% in a tailored hybrid composite structure. An inbuilt C-sp 2 shell structure of the crystallites is characterized in terms of its characteristic phonon bands in a conjoint polymer network, which are accounted well in modified XPS bands in the surface species.* Barkha Tiwari, barkha@matsc.iitkgp.ernet.in | Publisher's Note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.