Luminescent properties of Eu2+ and Ce3+ ions in strontium litho-silicate Li2SrSiO4

The luminescent properties of Eu2+ and Ce3+ ions in Li2SrSiO4 have been studied upon excitation in the 2–20 eV region. Based on the results of luminescent measurements, values of the crystal field splitting and the centroid shift of the Ce3+5d configuration in Li2SrSiO4 were found and compared with those of Ce3+ ions in some other inorganic compounds. The Eu2+ ions in Li2SrSiO4 exhibit a broad band emission with a maximum at 576 nm, which is due to the 4f65d→4f7 transition. It was shown that the long-wavelength position of the Eu2+ emission in Li2SrSiO4 is caused by the large crystal-field splitting of the Eu2+ 4f65d configuration and relatively high degree of covalency of the Eu–O bond. The stabilization of Eu2+ ions in Li2SrSiO4 during the synthesis process requires a strong reducing agent. Two phenomenological approaches to explain the low stability of Eu2+ in Li2SrSiO4 are also discussed.