Orange and reddish-orange light emitting phosphors: Sm3+ and Sm3+/Eu3+ doped zinc phosphate glasses

A spectroscopy study of Sm3+ and Sm3+/Eu3+ doped zinc phosphate glasses is performed through photoluminescence spectra and decay time profile measurements. Under Sm3+ excitation at 344 nm, the Sm3+ singly doped glass shows an orange global emission with x=0.579 and y=0.414 CIE1931 chromaticity coordinates, whereas the Sm3+/Eu3+ co-doped sample exhibits orange overall emissions (x=0.581 and y=0.398, and x=0.595 and y=0.387) and reddish-orange overall emission (x=0.634 and y=0.355) upon excitations at 344, 360 and 393 nm, respectively. Such luminescence from the co-doped sample is originated by the simultaneous emission of Sm3+ and Eu3+. Under Sm3+ excitation at 344 and 360 nm, the Eu3+ emission is sensitized and enhanced by Sm3+ through a non-radiative energy transfer process. The non-radiative nature was inferred from the shortening of the Sm3+ lifetime observed in the Sm3+/Eu3+ co-doped sample. An analysis of the Sm3+ emission decay time profiles using the Inokuti-Hirayama model suggests that an electric quadrupole-quadrupole interaction into Sm-Eu clusters might dominate the energy transfer process, with an efficiency of 0.17.