Aloe-vera Mediated Synthesis of Eu3+ doped CaIn2O4-carbon Hybrid Nanostructure and its Light Emission Properties

Abstract

The Eu3+ doped CaIn2O4 is a novel oxide phosphor useful for multifunctional applications such as display systems, lasers, energy-converters, photocatalysts, optical imaging, medical tools, and several others. Here, a natural aloe-vera gel is explored to obtain a precursor gel bridging Eu3+, Ca2+ and In3+ cations in a network so that it yields Eu3+:CaIn2O4 of small crystallites bonding over a grafted C-sp2 surface layer. The Eu3+ in varied from 0.1 to 2 mol% promptly promotes blue and red light-emissions in two major bands over 300-580 nm and 600-900 nm in 5DJ → 7FJ′ (J = 3, 2, 1 and J′ = 4 →1) and 5D0 → 7F1→ 4 transitions in the Eu3+ species, what is it is required in many optical and catalytic devices. The novel results are described in correlation to the light absorption and core-shell nanostructure.

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

“…As expected, an initial C-content has been progressively reduced in optimally annealed samples at 400-600 °C for 1-2 h in air. The primary band-1, which is observed at 205 nm (215 nm before the annealing) [35] in Fig. 14a in a sample doped by only 0.1 mol% Eu 3+ , is shifted progressively over lower λ-values below 200 nm and only its tail extends over longer λ-values above 200 nm in a distinct band edge absorption.…”

“…Qualitatively, the first two bands observed at 528.9 eV and 529.6 eV in strong intensities attribute to O 2− species occupying the two kinds of the oxide polygons of CaO 4 6− and InO 6 9− respectively as per their ratio 1:2 in a spinel CaIn 2 O 4 structure. Thus, a weak satellite band observed at 530.3 eV (or 531.8 eV in the undoped sample) can be assigned to the surface O 2− species present as functionalized groups, like C=O, C-O, or CHO [33][34][35], in a conjoint C-sp 2 surface layer of a stable network on the individual crystallites in a hybrid core-shell structure. It is a hybrid core-shell structure that finely tunes the E b values and intensities in the three distinct overlapping O1s bands in a wide O1s distribution of electrons in the different sites in the lattice in this example.…”