Probing into photoluminescence properties of trivalent rare earths (Gd3+/Tb3+/Dy3+/Eu3+) activated fluoro-elpasolites

Natural K₂NaAlF₆ compound is known to exist in elpasolite structure form, since years. In recent times, such fluoro-elpasolites activated by small amounts of Mn⁴⁺ have emerged as most propitious red-phosphor for solid-state lighting purposes. Fluoro-elpasolites such as K₂LiAlF₆ and K₂NaAlF₆ are easy to prepare via simple precipitation method. In present work, fresh photoluminescence studies on rare earth-doped trivalent ions are reported in these hosts. Gadolinium added phosphors showed interesting PL properties with different concentrations. Also, really long lifetimes of luminescence decay curves were recorded for these phosphors. Other dopants such as terbium, dysprosium and europium in their trivalent form also showed their characteristic PL spectra. Previously, PL studies on Eu²⁺ and Ce³⁺ doped on these compounds have been already done and reported elsewhere. Phase-structural, morphological and elemental analysis has been also carried out on these compounds using various XRD, SEM and EDS techniques. Particles are found to be of bigger size then 1 µm i.e. in micro-range using DLS measurement. In the end, CIE coordinates and CCT(K) were calculated for phosphors, with PL emissions lying within the visible range of radiation spectrum.