Temperature dependence of the luminescence of Li6GdxY1-x(BO3)(3): Eu crystals

Abstract

The luminescence and recombination processes in crystals of lithium borates Li 6Gd x Y 1 - x (BO 3) 3:Eu (LGYBO:Eu) have been studied. The photoluminescence (PL) spectra upon selective photoexcitation to lower excited states of Gd 3+ and Eu 3+ ions and the temperature dependences of the photoluminescence intensity at different energies of excitation photons have been measured in a wide temperature range: 10-500 K. We observed a photoluminescence band at 3.97 eV, which is due to the 6 P J → 8 S 7/2 transitions in Gd 3+ ions, and a characteristic line spectrum in the range of 1.6-2.2 eV, which is related to the radiative f-f transitions in impurity Eu 3+ ions, occurring mainly from the lower excited 5 D 0 level to the 7 F J states (J = 0, 1, ⋯, 6). The influence of the O-Eu charge transfer states and the vibrational relaxation between the 6 I J and 6 P J levels of the Gd 3+ ion on the temperature dependences of the intrinsic and impurity luminescence intensities is discussed. © 2012 Pleiades Publishing, Ltd.