Synthesis and luminescence spectroscopy study of a novel orange-red colour emissions phosphor based on Tb3+ ion-doped Na2 ZnP2 O7.

Here, we report the synthesis and study of new orange-red (OR) colour-emitting phosphors Na2 ZnP2 O7 :xTb3+ (x = 1, 1.25, 1.5, and 1.75 mol%) using a conventional solid-state reaction. The sample crystallographic structures and their room temperature photoluminescence properties were measured using X-ray powder diffraction, excitation and emission spectra, as well as emission decay curves. X-ray diffraction analysis showed an isostructural tetragonal structure for all the doped materials with no impurities. Several colour emissions corresponding to 5 D4 →7 F6 (blue), 5 D4 →7 F5 (green), 5 D4 →7 F4 (orange) and 5 D4 →7 F3,2,0 (red) intraconfigurational transitions were observed and investigated. These colours were dominated by the OR colours. 5 D4 energy level lifetime was independent of Tb3+ concentration. Various radiative and luminescence parameters, such as experimental branching ratio, radiative decay rate, and luminescence quantum efficiencies, were calculated and discussed. Chromaticity diagram calculations illustrated an orange emission for all the studied materials.