Pr³⁺-doped YF₃, LaF₃, and GdF₃ nanoparticles: comparative crystallographic, Raman, optical, and photoluminescence properties

Pr³⁺-ion doped YF₃, LaF_3, and GdF₃ nanoparticles (NPs) were chemically prepared at a lower temperature (80 °C) to investigate the comparative physiochemical characteristics. X-ray diffraction profile of the nanoproducts exhibited the orthorhombic phase in YF₃:Pr and GdF₃:Pr NPs, whereas hexagonal structure was found in LaF₃:Pr NPs with an estimated crystalline size 12, 23, and 15 nm, respectively. The unit cell constants for YF₃:Pr (a = 6.340 Å, b = 7.269 Å, c = 4.317 Å, and unit cell volume = 198.97 (Å)³), LaF₃:Pr (a = b = 7.171 Å, and c = 7.388 Å, and unit cell volume = 329.092 (Å)³) and GdF₃:Pr (a = 6.465 Å, b = 7.008 Å, and c = 4.528 Å, and unit cell volume = 205.225 (Å)³) were considered to examine the influence of the dopant ions and the host ion’s ionic radius on the crystal phase, and crystallinity. An orthorhombic phase GdF₃:Pr NP sample revealed better thermal stability in comparison to the hexagonal phase LaF₃:Pr NPs as received in the thermogravimetric outcomes. FTIR spectra exhibited the surface-fastened water molecules which promote the development of colloidal solution in aqueous solvents under the environmental conditions as achieved in absorption spectral analysis. Band gap energy was calculated from the UV/visible spectra to examine the optical behavior of the optically active NPs. The excitation and emission spectrums demonstrated the sharp excitation and emission transitions of the doped Pr³⁺ ion under excitation from the blue region. Comparatively, the emission and excitation transitions of the YF₃:Pr NPs were dominant with respect to the orthorhombic GdF₃:Pr and hexagonal LaF₃:Pr NPs. YF₃:Pr NPs are a useful host matrix for the loading of the activator Pr³⁺-ion for their use in luminescent phosphor material development.