Pd-induced quenching of the UV emission from Gd ions in phosphate glass.

This paper reports on the influence of Pd ions on the ultraviolet emission from Gd, investigated in barium phosphate glass as model matrix. The glasses were prepared by the melting technique and characterized by X-ray diffraction (XRD), Fourier transform-infrared (FT-IR) spectroscopy, optical absorption, 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 PO tetrahedra. The optical absorption analysis showed that addition of PdO up to 0.3 mol% lead to significant growth of the visible Pd d-d absorption band around 415 nm, with ultimately some decrease in the optical band gap energies assessed through Tauc plots. Further, significant PL quenching of Gd ions emission around 312 nm was observed with increasing PdO contents, alongside increased decay rates for the P emitting state in Gd. An analysis of quenching constants was ultimately performed comparing results from emission intensity with the decay rates. It is suggested that a Gd → Pd excitation transfer and/or absorption competition lead the quenching process with a contribution from a channel depopulating the P metastable state.