Bi3+ assisted luminescence in SrMoO4:Sm3+ red phosphors

In this paper, we report synthesis of pure SrMoO₄, Sm³⁺ (1 at%–5 at%) doped SrMoO₄ and Bi³⁺ (1 at%–3 at%) co-doped in 4 at% Sm³⁺ doped SrMoO₄ (SrMoO₄:4Sm³⁺) phosphors by solution combustion method. The X-ray diffraction (XRD) analysis reveals the tetragonal phase of all samples, also Bi³⁺ co-doping supports crystallite size growth and reduces lattice strain. Absorption analysis of Sm³⁺ doped SrMoO₄ ascertains a decrease in band gap and Bi³⁺ co-doping confirms the emergence of an absorbance peak at around 308 nm attributed to Bi³⁺ energy levels. Photoluminescence (PL) analysis ascertains an increase in emission peaks for Sm³⁺ doped SrMoO₄ up to 4% concentration, which are attributed to an electron transition from ⁴G_5/2 to ⁶H_J (J = 5/2, 7/2, 9/2, and 11/2) energy levels of Sm³⁺ ions. We have explained the effects of Bi³⁺ co-doping on the luminescence of Sm³⁺ doped SrMoO₄. The reduced microstrain and increased crystallinity of the phosphors as a result of Bi³⁺ co-doping and their correlation with the luminescence of Sm³⁺ ions are discussed.