Impact of Li concentration in KMgF3:Eu,Yb fluoroperovskite on structure and luminescence properties

In this work, europium, ytterbium, and lithium doped fluoroperovskite type-KMgF3 (KMgF3:Eu,Yb,Li) was synthesized using the sol-gel method. The structural and luminescence properties of KMgF3:Eu,Yb,Li compound were investigated by radioluminescence, thermoluminescence (TL), and optically stimulated luminescence (OSL) methods. Different contents of the alkali metal lithium (Li) co-dopant have been studied regarding the influence on the structure and luminescence properties. The structures of the samples were studied using the x-ray diffraction (XRD) method. We found cubic-KMgF3 (Parascandolaite) and tetragonal-MgF2 phases for all produced samples. Additional Eu, Yb doping, and Li co-doping resulted in the formation of hexagonal-Li2O2 and cubic-MgO phases while reducing the MgF2 phase in KMgF3 dispersions that were confirmed with XRD and Rietveld refinement analyses. Moreover, the lattice parameters of KMgF3 were calculated for the undoped and Li co-doped samples. Scanning electron microscope images revealed increased crystalline formations with increasing Li concentration in the structure. Fourier transform infrared spectroscopy indicated a reduction of Mg-F bands for all samples due to Mg+2 ion substitutions with Eu, Yb doping, and Li co-doping. It was observed that the intensity of the TL peaks in the TL glow curves appeared as the Li concentration increased without shifting the peak positions as a function of temperature. The OSL curves of KMgF3:Eu,Yb,Li decayed slowly and the luminescence intensity reached a maximum with 15 mol% Li content. The obtained results tend to suggest that the investigated Eu- and Yb-doped and Li codoped parascandolaite polycrystals exhibit promising luminescent properties and could be considered as appropriate candidates for various technological applications including radiation dosimetry. (c) 2022 Elsevier B.V. All rights reserved.