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Structural and optical properties of Nd3+ doped GeO2-PbO glass modified by TiO2 were investigated. The glass composition studied was (59-x)GeO2-41PbO-xTiO2, where x = 0, 1, 2 and 5 mol%. X-ray diffraction confirmed the amorphous nature of the samples. The glass transition temperature increased with the increase of the TiO2 content. The sample containing 1 mol% of TiO2 presented the largest values of density (6.5 g/cm3), refractive index (2.01 at 550 nm) and optical bandgap (3.24 eV) compared with the other TiO2 concentrations. A blue shift in the absorption edge and an enhancement of the luminescence in the NIR spectral region under UV-VIS excitation were observed for the Nd3+ doped-58GeO2-41PbO-1TiO2 glass.

Luminescent properties and energy transfer processes in GeO2-PbO glasses co-doped with Sm3+/Yb3+ were investigated. The concentration of Sm3+ was 1 mol% while the concentration of Yb3+ was 0.2 and 0.5 mol%. Judd–Ofelt intensity parameters Ω λ ( λ = 2,4,6 ) were calculated from absorption spectra of the co-doped glass samples, together with transitions probabilities A j j ′ and radiative lifetimes τ R . Visible and NIR emission spectra were obtained under excitation of wavelengths corresponding to the 6H5/2 →(6P7/2,6P3/2,4I11/2) transitions of Sm3+ resulting in different emission channels from 4G5/2 level energy to lower energy levels. The set of co-doped and undoped glasses were placed on the top of a conventional silicon solar cell and the relative efficiency was studied. Cooperative energy transfer between the Sm3+ ion and Yb3+ ion would probably be responsible for observed enhancement in the energy efficiency of about 10%.

Heavy metal oxide B2O3–PbO–Bi2O3–GeO2 transparent glass doped with Sm3+ was synthesized and implanted with Au+ using energy of 300 keV and fluence of 1 × 1016 cm−2. The annealing of the implanted glass at moderate temperature below the glass transition temperature induced the nucleation of gold nanoparticles, confirmed by the characteristic absorption band in the visible range and by transmission electron microscopy. Using Mies and Doyles theories for the surface plasmon resonance, the average size of the gold nanoparticles was about 4.6 nm, similar to the values observed by transmission electron microscopy. It was also observed the crystallization of a thin layer of the glass at the implanted surface after annealing, detected by X-ray diffraction and scanning electron microscope. Visible and near-infrared emission of Sm3+ was enhanced after annealing of the glass implanted with gold. Judd–Ofelt parameters and radiative parameters were calculated for the glass doped with Sm3+ with and without gold nanoparticles.

The aim of this work was to investigate the effect of high pressure and high temperature on the refractive index of lithium disilicate glass ceramic with the stoichiometric composition Li 2 O·2SiO 2 (LS 2 ). A first group of monolithic LS 2 glass samples were processed at 2.5 GPa, 4 GPa and 7.7 GPa at room temperature and a second group was submitted to high pressure and, simultaneously, to heat treatments for nucleation and growth of the crystalline phases. For comparison, samples submitted to the same heat treatments at 1 atm were also investigated. The refractive index of the samples was obtained by spectral ellipsometry and the results were clearly dependent on the particular pressure and temperature conditions. The crystallization of the samples was investigated by X-ray diffraction. For the samples processed under high temperature at 1 atm and at 2.5 GPa a fraction of the originally amorphous glass was transformed to a monoclinic phase of lithium disilicate. For the samples processed under high temperature and at 4 GPa, a large fraction of the originally amorphous glass transformed to an orthorhombic phase while, at 7.7 GPa, it was observed the formation of lithium metasilicate.