Impact of Li concentration in KMgF 3 :Eu,Yb fluoroperovskite on structure and luminescence properties

In this work, europium, ytterbium, and lithium doped fluoroperovskite type-KMgF 3 (KMgF 3 :Eu,Yb,Li) was synthesized using the sol-gel method. The structural and luminescence properties of KMgF 3 :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-KMgF 3 (Parascandolaite) and tetragonal-MgF 2 phases for all produced samples. Additional Eu, Yb doping, and Li co-doping resulted in the formation of hexagonal-Li 2 O 2 and cubic-MgO phases while reducing the MgF 2 phase in KMgF 3 dispersions that were confirmed with XRD and Rietveld refinement analyses. Moreover, the lattice parameters of KMgF 3 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 KMgF 3 :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 co-doped parascandolaite polycrystals exhibit promising luminescent properties and could be considered as appropriate candidates for various technological applications including radiation dosimetry.