VUV spectroscopic properties of rare-earth (RE3+= Sm3+, Eu3+, Tb3+, Dy3+) -activated layered borate Ba6Gd9B79O138

Abstract

Vacuum ultraviolet (VUV) spectroscopic properties of rare-earth RE3+- activated (RE3+ = Sm3+, Tb3+ and Dy3+) Ba(6)al(9)B(79)O(138) borates (BGBO) are investigated. The strong absorption bands in the VUV range of un-doped and RE3+-activated BGBO were observed. The band range from 140 to 200 nm with a peak at about 173 nm results from the host lattice absorption. For Sm3+-activated BGBO, the charge transfer transition from O2- to Sm3+ was observed at 202 nm. In addition, it exhibits bright red emission originating from the Sm3+ f-f transitions of (4)G(5/2) -> H-6(J) (J = 5/2, 7/2 and 9/2). The O2--Eu3+ charge transfer (CT) at 249 nm is observed in the excitation spectrum for Eu3+-doped BGBO. For Tb3+-activated BGBO, the broad bands around 208 and 230 nm are due to the spin-allowed and spin-forbidden f-d transitions of Tb3+, respectively. In addition, the absence of the f-d transitions of Sm3+ and Dy3+ in the excitation spectra probably due to the photo-ionization effect. It is demonstrated that there are energy transfers from the BGBO host lattice to the luminescent activators depending on the activators. (C) 2016 Elsevier Masson SAS. All rights reserved.