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In this work, the series of silicate xerogels co-doped with Gd3+ and Eu3+ ions have been synthesized via a sol-gel method and further processed into nano-glass-ceramic materials. The mutual molar ratio of trivalent metal ions' acetates in samples' compositions was gradually modified as follows: La3+:Gd3+:Eu3+ = (0.95-x):x:0.05, x = 0.05, 0.25, 0.45, 0.65, and 0.90; hence the molar ratio of Gd3+:Eu3+ (R Gd/Eu) was set from 1 through 5, 9, 13 up to 18. XRD measurements confirmed the amorphous nature of fabricated xerogels, but their heat-treatment successfully triggered the crystallization of hexagonal LaF 3 fraction with an average size of about ∼10 nm, which was additionally confirmed by HR-TEM microscopy. Additionally, it was found that the LaF 3 phase crystallized in a whole range of proposed La(CH 3 COO) 3 :Gd(CH 3 COO) 3 molar ratio, and Gd3+ ions played only the role of dopant and replaced La3+ cation in the fluoride crystal lattice. The optical characterization of prepared sol-gel samples involved the registration of absorption, excitation and emission spectra, along with the luminescence decay analysis from the 6P 7/2 (Gd3+) and the 5D 0 (Eu3+) excited states. For nano-glass-ceramics defined by R Gd/Eu = 13 and 18, the unexpected prolongation of the τ(6P 7/2):Gd3+ lifetimes was denoted, compared with samples singly-doped with Gd3+. The changes in photoluminescence behavior of studied samples are strongly dependent on the nature of the fabricated sol-gel samples, the established molar ratios of La3+:Gd3+:Eu3+, and the tendency of cation-exchange in LaF 3 nanocrystal lattice by Gd3+ and Eu3+ ions. [ABSTRACT FROM AUTHOR]

The effects of selective components M 2 O 3 (M=Al, Ga) on local structure, thermal and spectroscopic properties of lead phosphate glasses doped with Er 3+ ions were systematically investigated. It was found that the both oxide modifiers (Al 2 O 3 and Ga 2 O 3 ) may be classified as crystallizing agents for lead phosphate glass host. The glass transition temperatures for glass samples modified by M 2 O 3 were determined using differential scanning calorimetry. The X-ray diffraction analysis was used in order to verify the nature of lead phosphate - based systems. Near-infrared luminescence spectra corresponding to 4 I 13/2 → 4 I 15/2 transition of erbium ions were measured. The luminescence spectra of Er 3+ -doped lead phosphate glass are presented and discussed in relation to the impact of crystallizing agents M 2 O 3 (M=Al, Ga). Luminescence lifetimes for the upper 4 I 13/2 laser state of Er 3+ ions were also evaluated. [ABSTRACT FROM AUTHOR]