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 4G5/2 to 6HJ (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.