Modified optical properties via induced cation disorder in self-activated NaMg₂V₃O₁₀

Cation disorder in the phosphor lattice could be one of the effective approaches to modify the luminescence efficiency. In this work, cation substitutions of (Mo⁶⁺→ V⁵⁺) and (Na⁺→ Mg²⁺) were conducted in the self-activated NaMg₂V₃O₁₀. All the samples of Na_1+xMg_2-xV_3-xMo_xO₁₀ (x = 0, 0.01, 0.05, 0.1, 0.2, 0.3) were prepared via solid-state reaction. The morphological properties were measured via SEM and EDS analyses. Structural Rietveld refinement was performed to investigate the microstructure in the lattices. The cation substitution brings about structural disorder in the phosphor, which exerts great modifications in the luminescence properties. NaMg₂V₃O₁₀ presents an intrinsic indirect transition with a band gap of 3.22 eV. The incorporation of Mo⁶⁺ and Na⁺ in the lattices moves the optical absorption to a longer wavelength bringing about a narrower band gap. The luminescence intensity, thermal stability and corresponding lifetime were modified by the cation disorder in the self-activated phosphor.