Photoluminescence study of mixed doped Ge-Se-In-Bi glasses

Photoluminescence studies, carried out using the Fourier Transform method rather than the conventional monochromator-dispersion method,are reported on glassy samples of indium-bismuth mixed doped Ge (10) Se(90-x-y) In (x) Bi (y) system (x,y = 5,10). The amorphous Bi2Se3 is found to be n-type like the crystalline counterpart. The possible contributions from microscopic cluster-level phase separation of Bi2Se3 and from the defects to the change in conductivity from p- to n- typein this system is discussed. The similar situation in related systems is also pointed out

Influence of Ag Doping on Physico-Chemical Properties of the Ge28Sb12Se60 Chalcogenide Glassy Matrix

International audienceThermal, optical and electrical properties of the Agx(Ge28Sb12Se60)100x system (for x = 0 to 20) are systematically studied using various characterization techniques. In the present study, we have shown the reproducibility of the current results with the previously published literature and several novel results are also presented. The impedance data for the understanding of electrical properties of the materials has been analyzed using the random-walk (RW) model. We observed that, Ag playing two different concentration dependent roles i.e. above and below the 5% of Ag concentration, which is confirmed by the Raman analysis. The anomalous behaviors of electrical conductivity, optical and thermal properties with increasing Ag concentrations are explained by the role of Ag in the structural modification. We compared the diffusion coefficient (D), obtained from the RW model analysis with the experimental data(obtained from tracer diffusion) and found diffusion coefficient (D), obtained from the RW model are in good agreement corresponded with the experimental values. We also found a major change in conductivity of insulating Ge28Sb12Se60 (~ 10-14 S·cm-1) to a fast ionic conductor for Ag15(Ge28Sb12Se60)85 (~ 10-6 S·cm-1), i.e., a nine orders of magnitude. We demonstrated that the random-walk model can replacea time consuming and expensive tracer diffusion method for the determination of D. The present article helps to understand the ion conduction mechanism in disordered / amorphous materials

Spectroscopy of infrared transitions of Pr3+ ions in Ga-Ge-Sb-Se glasses

International audienceElectronic transitions of Pr3+ ions in Ga-Ge-Sb-Se glasses corresponding to emissions in the infrared region were studied by means of absorption and emission spectroscopies and fluorescence lifetimes measurements. Transition probabilities, radiative lifetimes, branching ratios, and quantum efficiencies of most of the emission transitions including the infrared ones occurring around 1.3, 1.7, and 2.4 μm were estimated based on a standard Judd-Ofelt analysis

Glass formation and properties of the TeO2-ZnO-BaO tellurite optical glasses

International audienceWe report the thorough study on glass forming ability and properties of the TeO2-ZnO-BaO (TZB) optical glasses prepared by the melt-quenching method at 900 °C. The attention has been paid to investigation of thermal, structural, and optical properties of glasses with content of TeO2 from 52.5 up to 90%. The introduction of ZnO and/or BaO into TeO2-based glass results in increase of the glass transition temperature Tg from 319 to 369 °C and decrease of the refractive index and density of prepared glasses. The structure of studied TZB glasses was investigated by Raman scattering. Since the TZB glasses exhibit good thermal stability, wide spectral region of transparency from ultraviolet (UV), λ ≈ 0.35 μm, up to mid-infrared (MIR), λ ≈ 6 μm, wavelengths with high values of refractive index (n1550 ≈ 1.87–2.04), they may be utilized as optical materials, which can be designed on the results presented in this paper

Green, red and near-infrared photon up-conversion in Ga–Ge–Sb–S:Er3+ amorphous chalcogenides

We report on compositional tuning in Et3+ ions doped Ga-Ge-Sb-S glassy system allowing for effective H-2(11/2) -> I-4(15/2) (530 nm), S-4(3/2) -> I-4(15/2) (550 nm), F-4(9/2) -> I-4(15/2) (660 mm), I-4(9/2) -> I-4(15/2) ( 810 nm), I-4(11/2) -> I-4(15/2) (990 nm) intra-4f electronic transition emissions of Er3+ ions under 808 nm, 980 nm or 1550 nm laser pumping. We changed the composition of well-known Ge20Ga5Sb10S65 glass to Ge25Ga10-xSbxS65, where x=0.5 at%, 2.5 at% or 5.0 at% and doped it with 0.5 at% of Er3+ ions. The short-wavelength absorption edge of the studied glassy hosts is blue-shifted by substitution of Sb with Ga to similar to 500 nm making the green emission at 530 nm and 550 nm and even 495 nm (F-4(7/2)-> I-4(15/2)) observable, while the glass stability was kept high characterized with the difference of T-c-T-g>100 K and mean coordination numbers 2.67-2.71. Up-conversion emission decay times of all anti-Stokes emissions were in the range of 0.2-2.1 ms. The influence of Ga substitution with Sb on the structure and the optical properties was investigated. The spectroscopic parameters for Er3+ ions with local environment change were analyzed based on Judd-Ofelt theory. (C) 2013 Elsevier B.V. All rights reserved.X111010sciescopu