Orangish-red light emitting LaSr2AlO5:Sm3+ nanophosphors for warm LEDs: Crystallographic, photoluminescence characteristics with high color purity and thermal stability

Gel-combustion method was implemented in current research to generate Strontium Lanthanum Aluminate (LaSr2AlO5) phosphors doped with Sm3+ ions and have a potential to emit orangish-red light. In order to analyze phase characteristics, XRD technique was employed. XRD patterns of synthesized materials were closely resembles the JCPDS pattern indicated on card no. 70-2197, which define the tetragonal symmetry of the material with I4/mcm space group. The morphological, optical band energies and elemental analyses were done via TEM, DRS and EDX investigation respectively. The Sm3+ activated LaSr2AlO5 phosphor's PL spectra monitored at 406 nm excitation indicate intense visible orangish-red emission at 602 nm owing to the 4G5/2→6H7/2 transition. Concentration quenching was obtained at 4 mol % content of Sm3+ owed to the dipole-dipole interaction among activated ions. The calculated lifetimes have been observed to shorten as content of Sm3+ ions in the phosphors rises. The CIE (0.6069, 0.3905) value, CCT (1382 K) value, 99.4 % color purity of the optimum sample was calculated which placed in orange-red space. The fabricated phosphor has excellent thermal durability up to 498 K and 0.1686 eV activation energy. Finally, the results of all the research allow us to consider that Sm3+ doped LaSr2AlO5 phosphor is appropriate for warm LEDs.