Spectroscopic investigations of Sm³⁺ doped Ca_0.5La(MoO₄)₂ phosphor for solid state lighting applications

The Sm³⁺- doped Ca_0.5La(MoO₄)₂ were successfully synthesized by the solid state reaction method. Indexed powder X-Ray diffraction pattern suggests the scheelite tetragonal crystal structure. Surface Morphology of the sample shows polyhedral morphology and the average particle size estimated from SEM image is 5.5 µm. The energy dispersive X-ray analysis confirms the existence of Ca, La, Mo, O, and Sm elements. The room temperature photoluminescence (PL) emission spectra of Sm³⁺- doped Ca_0.5La(MoO₄)₂ with various concentrations upon 404 nm excitation were recorded. The PL emission spectra show three intense emission peaks at 565, 600 and 647 nm were owing to the f–f electronic transitions of 4f electrons of Sm³⁺ attributed to the transitions ⁴G_5/2→⁶H_5/2, ⁴G_5/2→⁶H_7/2 and ⁴G_5/2→⁶H_9/2 respectively. Among them, bright orange-red visible emission is obtained due to ⁴G_5/2→⁶H_9/2 transition. The decay time and color chromaticity co-ordinates were estimated. From the obtained results, the prepared powder phosphor Ca_0.5La(MoO₄)₂:Sm³⁺ stands as a suitable candidate for the display and solid state lighting applications.