Exploring the Role of Sm³⁺ Concentration in Controlling the Structural Stability, Morphology Tunability, Optical Performance, and Luminescent Efficiency of NaLa<i>_<i>x</i></i>Sm_1–<i>x</i>(MoO₄)₂

In this work, a highly effective oleic acid assisted hydrothermal method has been employed for the large-scale synthesis of NaLaxSm1–x(MoO4)2 (x = 1, 0.75, 0.50, 0.25, and 0) nanophosphors. These nanophosphors crystallize in a pure tetragonal phase, exhibiting a remarkable morphological evolution from spherical nanoparticles to nanoplatelets and nanorice structures. The role of oleic acid as both a capping agent and shape modifier is crucial in tailoring the morphology, thereby influencing the optical properties. Structural and elemental analyses through SEM and TEM confirm the well-defined features and stoichiometric composition of the synthesized materials. Beyond their fascinating structural versatility, these nanophosphors demonstrate intense and tunable luminescence in the visible region, governed by the Sm3+ concentration. Under ultraviolet excitation, they emit a strong orange-red light, attributed to the characteristic f–f transitions of Sm3+ ions. Photoluminescence analysis further confirms the enhancement in luminescence efficiency, with an optimized Sm3+ doping concentration yielding superior quantum efficiency for optoelectronic applications. The ability to modulate the morphology and luminescence properties makes NaLaxSm1–x(MoO4)2 (x = 1, 0.75, 0.50, 0.25, and 0) nanophosphors highly promising for advanced applications. This work paves the way for multifunctional luminescent materials with tailored properties for cutting-edge photonics, LEDs, security protection, and micronano optical functional device applications.