Synthesis and investigation of energy transfer mechanism in Sm3+ and Eu3+ doped Na6Mg(SO4)(4) nanophosphors via solution combustion technique

Singly doped Sm3+(1.0 mol%), Eu3+(1.0 mol%) and co-doped Na6Mg(SO4)(4):Sm3+/Eu3+ nanophosphors with a fixed Sm3+(1 mol%) concentration and different Eu3+ (x = 0.5%, 1.0 and 1.5 mol%) concentration were synthesized using the chemical combustion method at a temperature of 580 C-0. Structural, morphological and optical properties were studied using different characterization techniques. X-ray diffraction confirmed the crystal structure of the Na6Mg(SO4)(4) nanophosphors to be monoclinic with different space groupings. The optical bandgap of the Na6Mg(SO4)(4) nanophosphors were calculated from the Kubelka-Munk function using optical data and a decrease in the bandgap after adding Sm3+ and Eu3+ dopants was obtained. The photoluminescence was measured with two different 404 and 395 nm excitation wavelengths, both from the Sm3+ and Eu3+ spectra, respectively. An improvement of the color tunability was observed in the co-doped Na6Mg(SO4)(4) nanophosphors, with an energy transfer from Sm3+ to Eu3+. The color purity of all the nanophosphors was analyzed using the CIE-1931 color chromaticity, which all confirmed red color emission. These luminescence results proved that the prepared nanophosphors are suitable to be used in display and light emitting diodes applications.