Structural, morphological and photoluminescence characterizations of Sm3+ doped Y2O3 nano-sized phosphors synthesized by ultrasound assisted sol-gel method

Nanosized 1 at% Sm3+ doped Y2O3 powders were prepared by an ultrasound assisted sol-gel method. Y2O3:Sm3+ powders crystallize in Y2O3 pure cubic phase and XRD analysis shows that the as-used agitation protocol affects strongly the crystallite's shape and mean size. The recorded emission spectra under λem=600nm exhibit two absorption bands; the first one is assigned to O2− → Sm3+ charge transfer state (CTS) with a maximum absorption at 223 nm, and the second is due to intra-configurational transition 4f5-4f5 of Sm3+ with a maximum absorption at 407 nm. The 223 and 407 nm transitions are attributed to characteristics intra-configurational transitions of Sm3+. All emission spectra are dominated by reddish/orange luminescence located at 606 nm and assigned to 4G5/2 → 6H7/2 transition. It is found that the photoluminescence intensity of samples obtained under excitation at 407 nm is 60 times smaller than that obtained under 223 nm excitation. Decay time measurements of the 4G5/2 → 6H7/2 luminescence transition indicate that decay time of nano-sized powder is significantly shorter than bulk material one.