Effect of silver co-doping on enhancement of the Sm3+ luminescence in lithium tetraborate glass

Abstract Luminescent properties of the Sm 3+ -doped and Sm 3+ -Ag co-doped glasses with Li 2 B 4 O 7 (or Li 2 O–2B 2 O 3 ) basic composition are investigated and analysed. Spectroscopic properties of the obtained Li 2 B 4 O 7 :Sm and Li 2 B 4 O 7 :Sm, Ag glasses were studied using measurements of optical absorption, electron paramagnetic resonance (EPR), photoluminescence (excitation, emission, decay kinetics), and quantum yield (QY) via an absolute method. Optical absorption spectra exhibit absorption bands related with transitions from the ground 6 H 5/2 state of Sm 3+ ions to several excited states. Photoluminescence spectra of the Sm 3+ -doped glasses reveal emission bands, which correspond to the 4 G 5/2 → 6 H J (J = 5/2–13/2) transitions of Sm 3+ ions. Luminescence excitation spectra and decay curves of the Sm 3+ luminescence also have been analysed. The EPR study confirms presence of Ag species in the Sm 3+ -Ag co-doped samples. Photoluminescence emission and excitation spectra and luminescence decay kinetics of the Ag + ions and small non-plasmonic molecule-like silver (ML-Ag) nanoclusters are observed and discussed. Enhancement of Sm 3+ luminescence in the Li 2 B 4 O 7 :Sm, Ag glass has been observed. Measurements confirm the increasing of external QY of the Sm 3+ luminescence in 1.43 times in the Ag co-doped glass. Such enhancement of the luminescence is attributed to the excitation energy transfer from Ag + ions and ML-Ag nanoclusters to the Sm 3+ ions. The obtained high QY of the Sm 3+ luminescence shows that Li 2 B 4 O 7 :Sm, Ag glasses belong to promising luminescent materials.