Optical Spectroscopy and Excited‐State Dynamics of Eu³⁺‐Doped Bismuth Borate Glasses Containing CuO

Abstract

Bismuth borate glasses containing phosphors and luminescent rare‐earths are of interest for applications in light‐emitting devices. Herein, the influence of CuO impurities on red‐emitting Eu3+‐doped bismuth borate glasses of the 25Bi2O3‐15BaO‐10Li2O‐50B2O3 type was investigated by various spectroscopic methods. The glasses were prepared by the melt‐quench technique and characterized by X‐ray diffraction (XRD), Fourier transform‐infrared (FT‐IR) spectroscopy, UV/Vis optical absorption (OA), and photoluminescence (PL) spectroscopy including decay kinetics assessment. The XRD data confirmed the amorphous nature of the glasses whereas FT‐IR spectra indicated the basic structural features of trigonal BO3 units and BO4 tetrahedra. The OA analysis showed that addition of CuO up to 0.5 mol% results in significant growth of the visible Cu2+ absorption band around 715 nm, with slight decrease in the optical band gap energies assessed through Tauc plots. A drastic PL quenching of Eu3+ ions emission was evidenced concurring with the detrimental effect of Cu2+. The assessment of the Eu3+ emission decay curves revealed significant lifetime decrease of the 5D0 emitting state with increasing CuO concentration. An analysis of quenching constants was finally performed comparing results from integrated PL data with the emission decay rates. It is argued that the bismuth borate glass system supports an effective Eu3+→Cu2+ energy transfer (more so than phosphates) in connection with a strong spectral overlap between Eu3+ emission and Cu2+ absorption.

Tm3+Ion Blue Emission Quenching by Pd2+Ions in Barium Phosphate Glasses: Fundamental Analysis toward Sensing Applications

“…The current results contrast with the report on the Gd 3+ –Pd 2+ interactions where the data appeared rather linear up to 0.3 mol % PdO with a quenching constant estimated at 4.0 (±0.7) mol % –1 . The k Q, I value estimated from the linear regression for the Tm 3+ –Pd 2+ pair up to 0.2 mol % PdO also turns out to be greater than that estimated for the Gd 3+ → Cu 2+ transfer in the barium phosphate system, the Eu 3+ → Cu 2+ transfer evaluated in bismuth borate glass, and the Sm 3+ → Cu 2+ transfer in aluminophosphate glass . The significant potential of Tm 3+ for being utilized as luminescent probe for Pd 2+ in analytical sensing applications is then supported.…”

“…22 The energy transfer efficiency thus benefits from shorter mean D−A distances and substantial spectral overlap. 42,43 In the present case, the use of 0.5 mol % Tm 2 O 3 led to D−A distances (Table 2) longer than the reported for the Gd 3+ doped phosphate system made with 2.0 mol % Gd 2 O 3 . 21 Hence, this implies that these mean distances are not able to support the more effective transfer for the Tm 3+ −Pd 2+ D−A pair.…”

“…The key factors to consider in the context of nonradiative energy transfer are (i) the D–A distance and (ii) the spectral overlap between donor emission and acceptor absorption . The energy transfer efficiency thus benefits from shorter mean D – A distances and substantial spectral overlap. , In the present case, the use of 0.5 mol % Tm 2 O 3 led to D – A distances (Table ) longer than the reported for the Gd 3+ doped phosphate system made with 2.0 mol % Gd 2 O 3 . Hence, this implies that these mean distances are not able to support the more effective transfer for the Tm 3+ –Pd 2+ D–A pair.…”