Excellent photoluminescence and electrochemical properties of Sm3+ doped Ca2MgSi2O7 nanophosphor: Display and electrochemical sensor applications

Abstract

A series of orange-red light emitting Ca2MgSi2O7:Sm3+ nanopowders were fabricated via low-cost eco-friendly green combustion technique using Aloe vera gel as fuel. The phase purity of the samples were confirmed by the powder X-ray diffraction (PXRD) technique. Pure single-phase tetragonal structure is observed from the PXRD results with no additional impurity peaks. The band gap energy of the fabricated powders was estimated by diffuse reflectance spectra (DRS) and is found to be in the range of 4.01–5.98 eV. A high resolution scanning electron microscope (SEM) was used to study the morphological behaviour of the samples. Honeycomb-like structures are observed from the SEM results. The particle size was evaluated by transmission electron microscopy (TEM) and is found to be ∼50 nm. The interplanar distance is found to be 0.53 nm. Photoluminescence properties were systematically studied in detail. The phosphors are successfully excited at 403 nm NUV light, producing reddish-orange characteristic emission. The emission peaks are centered at 558 (4G5/2 → 6H5/2), 607 (4G5/2 → 6H7/2) and 645 nm (4G5/2 → 6H9/2), respectively. Among the observed peaks the red emanation (4G5/2 → 6H7/2) is stronger than the orange emission (4G5/2 → 6H5/2) in the current investigation. The photoluminescent concentration quenching is noticed above 5 mol% Sm3+ ion doping content. The dipole–dipole interaction resulting in cross relaxation is found to be the principal cause of concentration quenching mechanism. The color features such as Commission Internationale de l’Eclairage (CIE) and correlated color temperature (CCT) were studied in detail. The optimized chromaticity coordinates were estimated to be (0.6363, 0.3632), which fall in the reddish-orange region. The average CCT value obtained is 3362 K. The average color purity is found to be ∼82%. Sm3+ incorporated Ca2MgSi2O7 samples are possible contender for single white light generation commercial candidates owing to their strong hypersensitivity of Sm3+ ions through host, least possibility for re-absorption of blue-green emission owing to poor direct f–f excitation of Sm3+ ions, and high color purity (reddish-orange emission). The prepared powders exhibit excellent electrochemical redox properties and CPE modified optimized powders show outstanding sensitive response which indicates its use in the potential electrochemical sensor materials for drug sensing studies.