SYNTHESIS, STRUCTURAL CHARACTERIZATION AND OPTICAL PROPERTIES OF Tb3+-DOPED MgF2 NANOCRYSTALS

Tb3+-doped MgF2 nanocrystals (NCs) were synthesized by a wet-chemical method and their structural, morphological, compositional, and optical properties were studied. XRD results confirmed the formation of phase tetragonal rutile-type MgF2, with diffraction peaks shifting slightly toward lower 2θ angles as the Tb3+ concentration increased. TEM images revealed nearly spherical NCs with particle sizes mainly in the range of 10–25 nm. EDX spectum analysis verified the presence of Mg, F, and Tb elements in the doped samples. Under 380 nm excitation, the MgF2:Tb3+ NCs exhibited characteristic Tb3+ emissions at approximately 488, 544, 586, and 621 nm, with the dominant green emission at 544 nm (5D4–7F5 transition). The emission intensity increased with Tb3+ concentration up to 4%, suggesting that concentration quenching was not significant within the investigated range. CIE analysis showed relatively high color stability with CCT values ​​ranging from 5314 K to 5526 K. Time-resolved PL decay curves were well fitted by a bi-exponential model. The average lifetime decreased from 4.13 ms to 2.60 ms with increasing Tb3+ concentration, reflecting enhanced Tb3+–Tb3+ interactions and non-radiative energy transfer. These results demonstrate that MgF2:Tb3+ NCs are promising green-emitting fluoride nanophosphors for UV/near-UV-excited photonic and optical applications.