Aloe-vera Mediated Synthesis of Eu 3+ doped CaIn 2 O 4 -carbon Hybrid Nanostructure and its Light Emission Properties

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Aloe-vera Mediated Synthesis of Eu3+ doped CaIn2O4-carbon Hybrid Nanostructure and its Light Emission Properties Barkha Tiwari, Shanker Ram and Pallab Banerji Materials Science Centre, Indian Institute of Technology, Kharagpur, India 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 5 DJ o 7FJc (J = 3, 2, 1 and Jc = 4 o1) and 5D0 o 7F1o 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. INTRODUCTION The compound CaIn2O4 of an inverse spinel structure is an important wide bandgap semiconductor, with bandgap Eg = 3.9 eV [1,2]. It is substantially stable and nontoxic for ecofriendly usages in electronic and optical devices. Like in other stable oxides, e. g., Al2O3, ZrO2, SiO2, etc. [3-5], an optical doping of Eu3+ ions is highly desired to devise light absorption and emission bands in near infrared, visible and ultraviolet regions with tailored properties for different applications of display systems, lasers, energy-converters, photocatalysts, optical imaging, and medical tools among several others. Different methods like sol-gel chemistry, solid state reaction, and co-precipitation out of a liquid precursor are being used in synthesizing Eu3+ doped phosphor oxides of controlled microstructure and functional properties for pertinent applications [6,7]. A major limitation with these routes is use of toxic reagents, which release a lot of pollution during the processing. To overcome these problems, green chemistry methods are being explored to produce such materials of controlled nanostructure and properties. Green gels from herbs offer an efficient reaction medium for producing noble metals and oxides of controlled size and/or shape with a grafted C-sp2 surface layer, and in turn tailored optical and other properties [8,9]. A natural aloe-vera gel contains polysaccharides what is it is suitable to bond cations in a network required to produce an oxide derivative of a specific microstructure. It is also a natural C-sp2 resource to form a hybrid phase of the product in the form of core-shell crystallites. Keeping these points in mind, in this investigation, we report synthesis of Eu3+ doped CaIn2O4C(sp2) hybrid nanostructures, with selective 0.1-2 mol% Eu3+ dosages, in optimizing the optical properties useful for devising light-emitters and other devices [10,11]. EXPERIMENTAL DETAILS The samples Eu3+:CaIn2O4 of 0.1, 0.5, 1.0 and 2.0 mol% Eu3+ dosages were prepared f