Photoluminescent properties of sol-gel derived (La, Gd)MgB5O10:Ce3+/Tb3+ nanocrystalline thin films

Ce3+ and/or Tb3+-doped (La, Gd)MgB5O10 nanocrystalline thin films were deposited on silica glass substrates by a sol-gel dip-coating process using triethyl borate B(OC2H5)3 as the boron source. The results of XRD indicated that the films have fully crystallized after annealing at 800 °C. The films are transparent, uniform and crack free with a thickness of about 300 nm, consisting of particles with an average grain size of 50 nm. The luminescence and energy transfer properties of Ce3+ and Tb3+ have been studied in the films. It is confirmed that the excitation energy of Ce3+ transfers to the Gd3+, migrates over the Gd3+ sublattices, trapped by the Tb3+ and resulted in its characteristic green emission (5D4-7F5 at 543 nm) in GdMgB5O10 nanocrystalline films as in the powder phosphors.