Photoluminescence behaviour of CaF₂:Eu³⁺ nanoparticles synthesized in different organic media and their metal ions sensing capabilities

CaF₂:Eu³⁺ nanoparticles (NPs) are important luminescent materials widely used in lighting, sensing devices, and display technologies. Here, CaF₂:Eu³⁺ nanoparticles (NPs) were synthesised at 100 °C by the coprecipitation method in different organic media, viz., ethylene glycol (EG), dimethyl sulfoxide (DMSO), 1,4-dioxane, N, N-dimethylformamide (DMF), aniline, phenylhydrazine, and salicylaldehyde. The structural, morphological, and optical properties of the nanoparticles were characterised using XRD, FESEM, EDX, FTIR, UV-Visible, and photoluminescence (PL) spectroscopy. The prepared CaF₂:Eu³⁺ nanoparticles are spherical and crystallized in the cubic crystal system. The prepared NPs exhibit strong luminescence intensity from magnetic dipole (⁵D₀→⁷F₁) and electric dipole (⁵D₀→⁷F₂) transitions of Eu³⁺, with maxima at 593 nm and 615 nm, respectively. The PL intensity of the NPs synthesised in different solvents is higher (optimum for EG) than that of those synthesised in other organic compounds. The luminescence intensity of the prepared NPs is significantly quenched in the presence of Fe³⁺ ions, without interference from other metal ions like Cu²⁺, Cr^2+, even when present together. These results indicate that the prepared NPs, regardless of the organic medium used for synthesis, exhibit efficient and selective fluorescent detection of the Fe³⁺ ion in aqueous media. The Limit of Detection (LOD) for Fe³⁺ ions in the sample prepared with EG is found to be 0.2916 ppm.