Photoluminescence properties of manganese activated calcium tungstate phosphors

Abstract

This study presents the novel Mn doped CaWO4 nanophosphors as an excellent alternatives of rare earth free materials for display application. The Mn doped CaWO4 phosphor were characterized by various techniques, such as UV–Vis-DRS, Raman, PL analysis. Scheelite type tetragonal structure with space group I41/a has been confirmed. Rietveld analyses confirms the formation of single-phase solid solution. Lattice parameters for Mn free and Mn doped samples were calculated and observed that cell volume decreases after Mn incorporation. FTIR and Raman studies confirm the involvement of functional group and vibrational modes of vibration in the compound. Band gap values are estimated to be in the range of 4.2 to 4.33 eV with Mn doping. Photoluminescence study confirms the strong green emission at 450 and 515 nm (d-d transition in Mn2+) after Mn doping. Also, it was observed that strong emission peak appears ~422 nm is mainly due to the electronic transition, 1 T2 → 1 A1 in [WO4] 2- tetrahedron of CaWO4 host matrices. CIE study confirms that prepared nanophosphor exhibits strong blue colour after Mn incorporation. It can be employed as a potential material for blue phosphors in LEDs applications.