Europium activator ion acting as an efficient luminescent probe to identify local symmetry in Li2ZnSn3O8:Eu3+ materials prepared by the MASS method

Abstract

Luminescent materials doped with rare earth ions (RE) have been intensely applied in several areas in the new photonic technologies, such as emergency lights, radiation detectors, biological markers, and anti-counterfeiting products. Stannate-based host matrices have attracted significant attention, as they are relatively inexpensive and have a favorable bandgap to allow the persistence luminescence phenomenon. In this work, Li2ZnSn3O8:Eu3+ was synthesized by the microwave-assisted solid-state method (MASS) using a domestic microwave oven after gridding Li2CO3, ZnO, SnO2, Eu2O3 precursor oxides. Therefore, the as-prepared precursors were heated in a static air atmosphere at a preset configuration of 900W for 20 min. The material was characterized by powder X-ray diffraction (PXRD), scan electron microscopy (SEM), and diffused reflectance spectroscopy. The PXRD patterns indicate the formation of the desired Li2ZnSn3O8matrix phase when doped with different concentrations of the Eu3+ ion, showing a high crystallinity. The photoluminescence properties were determined based on the emission spectra of the Li2ZnSn3O8:mol%Eu3+ materials (Fig 1), showing intense yellowish-orange and reddish-orange emission colors under UV excitation at 282 and 336 nm, respectively. Moreover, both spectra show narrow emission bands characteristic of 5D0 →7F0-4 Eu3+ transitions. Sinceeuropium ions are powerful spectroscopic probes for the symmetry of the first coordination sphere of these ions in a lattice, and the spectral profiles change with the incident radiation wavelengths, which demonstrates the presence of more than one site of symmetry around the chemical environment of the Eu3+ion.Finally, it is noteworthy that these luminescent materials can be selectively excited in the UV range, leading to more than one specific emission spectral profile, which can be applied as efficient luminescent probes for anti-counterfeiting products.