Evolution of the spectral characteristics upon annealing of lithium borate glasses containing europium and aluminum

The spectral and structural characteristics of lithium borate glasses containing europium and aluminum have been investigated upon annealing at different temperatures. It has been found that the spectral characteristics of the studied system change nonmonotonically with an increase in the annealing temperature. After annealing at a temperature of 600°C, the luminescence spectra of the glasses exhibit broad structureless bands that are specific for the amorphous phase containing Eu³⁺ ions. Then, after annealing at T = 700°C, narrow lines appear in the wavelength ranges 585–595 and 610–620 nm, which correspond to the luminescence of the Eu(BO₂)₃ and EuAl₃(BO₃)₄ borates. A further increase in the annealing temperature (T = 800–900°C) leads to the disappearance of europium aluminum borate. In the luminescence spectra of these samples, there are narrow bands in the wavelength range λ = 585–595 nm, which are typical of europium metaborate. Finally, at a temperature of 1050°C, these bands disappear and narrow lines appear again in the wavelength range 610–620 nm, which are characteristic of the EuAl₃(BO₃)₄ borate. Thus, the temperature annealing makes it possible to purposely change the spectral characteristics of the studied system in the wavelength range 590–615 nm.     

Laws of changing the structure and properties of metallic glasses upon annealing and local mechanical loading

The behavior of metallic glass structure and properties upon annealing and local mechanical loading is investigated. Based on the results obtained, an energy model of plasticity behavior upon annealing and an atomic reorganization model upon local mechanical loading are suggested.     

Effect of microimpurities on the intensity of luminescence in optical glasses

Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 53, No. 5, pp. 750–754, November, 1990.     

Nonlinear optical properties of commercial semiconductor-doped glasses

We report new observations made on semiconductor-doped glasses commercially available. We have observed that the modulus of the Kerr susceptibility is proportional to the absorption coefficient below, across and above the gap. We have measured the phase of this susceptibility for various values of the excess energy. We have also observed a blue shift of the absorption edge following pulsed excitation and have measured the diameter of the crystallites to be 70–80 Å. The band-filling model is the most appropriate to account for the nonlinear properties of these glasses.     

Effects of annealing and high radiation dose on the thermoluminescence characteristics of natural fluorite

In this study, the various dosimetric properties of the thermoluminescent (TL) phosphor of CaF₂:natural including response characteristics, sensitivity to thermal annealing and decay of stored energy were investigated in detail. The analysis of the peak temperature values and the half widths of the resolved components in the glow curves, by using the Computerized Glow Curve Deconvolution (CGCD) Method, resulted in the activation energy (E) of 0.85–1.83 eV and frequency factor (s) of 6.17E+9–2.90E+15 s^?1. The effects of pre-irradiation thermal annealing on the radiation-induced sensitization of the thermoluminescent response of CaF₂:natural were presented. An enhancement of sensitivity after being subjected to a high beta particle exposure was clarified. The effect was complicated by the influence of heat treatments before the exposure to radiation. Replicate runs on CaF₂:natural after irradiation with 1 Gy absorbed dose indicated good reproducibility of peak temperatures and intensities; they can be re-used for repeated measurements. It appeared that the main dosimetric peak at 280 °C exhibits negligible fading over 4 weeks and may be used for dosimetry. This study has demonstrated that the potential exists for the use of CaF₂:natural for TL radiation dosimetry.     

Effect of some doping elements on the ionic conduction of mixed alkali-alumino-borosilicate glasses

Summary Some borosilicate glasses containing an equimolar ratio of different alkali types (K⁺ and Na⁺ ions) doped with 0.1 mole% R (R=Mn, Tb, Y, or Gd) were prepared. The results of d.c. electrical conductivity show that the absolute values of resistivities and the corresponding activation energies for the doped glasses are lower than those for glasses without doped ions. This behaviour is explained on the basis of the formation of elastic dipoles in such glasses and of the change of their fields owing to the existence of the doping ions. By thermal treatment of these glasses, it is found that the activation energies for the doped glasses are different from those obtained for glassess prepared without doping ions. This peculiarity is explained on the basis of the phase separation process in such glasses.     

Intrinsic dosimetry: Elemental composition effects on the thermoluminescence of commercial borosilicate glass

Intrinsic dosimetry is the method of measuring total absorbed dose received by the walls of a container holding radioactive material. By considering this dose in tandem with the physical characteristics of the radioactive material housed within the container, this method can provide enhanced pathway information for interdicted radioactive samples. Thermoluminescence (TL) dosimetry was used to measure ionizing radiation dose effects on stock borosilicate glass. Differences in TL glow curve shape and intensity were observed for glasses from different geographical origins. The different TL signatures strongly correlated with the concentration of alkaline earth metals and the ratio of sodium to the total amount of alkali metal present in the borosilicate glass.     

Effect of picosecond radiation intensity on nonlinear absorption of glasses with silver nanoparticles

The dependence of the process of nonlinear absorption on the intensity of laser radiation of a picosecond duration was studied with the use of the second harmonic of a Nd:YAG laser (λ = 532 nm, τ = 55 ps). The values of the nonlinear absorption coefficient and of the imaginary part of the third-order nonlinear susceptibility of materials were measured. The nonlinearity of absorption in the materials under study was found to be caused by the saturation of absorption.     

Measurements of the trapped-carriers nonlinearity of commercial semiconductor doped glasses

Interband absorption change dispersions due to the filling of the trapping states are measured in commercial semiconductor doped glasses. The corresponding refractive index changes are obtained through the Kramers-Kronig transformation. Our results indicate a large deep-trapping-states nonlinearity in this material.     

Effect of annealing upon the structure and adhesion properties of sputtered bio-glass/titanium coatings

Bio-glass films were deposited by radio-frequency magnetron sputtering technique onto medical grade Ti6Al7Nb alloy substrates from prepared silica based bio-glass target. A low deposition temperature was used (150 °C) and three different working pressures, followed by annealing in air at 550 and 750 °C. A quasi-stoichiometric target to substrate atomic transfer was found for Si, Ca and P, along with strong enrichment in Na and depletion in K and Mg, as evidenced by the energy dispersive microanalysis. The best results, taking into account stoichiometry and surface roughness, were obtained for the BG layers deposited at 0.3 Pa argon working pressure. The infrared spectroscopy of the as-sputtered and of the annealed films evidenced the characteristic molecular vibrations of silicate, phosphate and carbonate functional groups. The as-deposited films are amorphous and became partly crystalline after annealing at 750 °C, as evidenced by X-ray diffraction. The pull-out measurements, performed with a certified pull-test machine, gave very strong film–substrate adhesion strength values. For the non-crystalline layers, the pull-out strength is higher than 85 MPa, and decreases after annealing at 750 °C to 72.9 ± 7.1 MPa. The main objective of this work was to establish the influence of the working pressure upon the composition and morphology of the as-deposited films, and of the annealing temperature upon structure and film–substrate adhesion.     

Ultra short pulse laser annealing of FeB metallic glasses

We present the results of picosecond laser annealing of as-quenched Fe₈₅B₁₅ and Fe₈₂B₁₈ metallic glasses. The influence of the laser radiation on the surface and bulk properties are studied using CrK X-ray diffraction and transmission Mössbauer spectroscopy. The X-ray data show that the amorphous nature of the surface of the samples can be improved with laser treatment. The mat (cooling) surfaces of the ribbons appear to be more affected by the laser treatment, and show a higher stability. The Mössbauer data reveal that laser annealing of ribbon surfaces also affects the bulk properties of these materials due to induced stresses from the surface layer. The magnetic properties of these materials can be modified by laser annealing.     

Radiation-induced thermoluminescence characteristics of feldspar upon different heat and microwave treatments

Feldspar minerals are well-known markers for thermoluminescence (TL)-based identification of irradiated foodstuff because of their high TL sensitivity and characteristic TL glow curves. Post-irradiation processing, particularly heating, may affect luminescence properties. In the present study, the effect of boiling, roasting, and microwave treatments on TL properties of irradiated (0, 5, and 10 kGy) feldspar was investigated. The TL glow peak faded (TL peak maxima shift towards higher temperature) upon boiling or roasting, which was mainly dependent upon treatment temperature and time. This effect was most apparent in the roasted samples. Liquid samples showed more changes in TL characteristics than solid samples upon microwave treatment; however, the effect was less prominent compared to those of roasting and boiling. TL ratios could not confirm the TL results when boiled and roasted samples were treated at ≥100 °C, whereas the microwave treatment showed a negligible effect on the TL ratio.     

Influence of annealing on magnetic properties of Co-based metallic glasses

The influence of low-temperature annealing on the magnetic hysteresis loop parameters of magnetostrictive Co-Si-B and nonmagnetostrictive Co-Fe-Si-B glasses was studied. The dependence of Curie temperature (T_C), crystallization temperature (T_x), full-stress-relaxation temperature, saturation magnetostriction constant, saturation magnetization and coercive field H_c on metalloids contents for as quenched Co_100-x(Si_0.5B_0.5)_x glasses was determined.It was found that annealing enhances remanence magnetization for all investigated Co-Si-B glasses. The coercive field of these glasses is influenced by annealing owing to: stress relaxation (resulting in an H_c decrease) and domain structure stabilization (resulting in an H_c increase). Significant H_c reduction for both magnetostrictive and non-magnetostrictive glasses was observed, after annealing above T_C. For glasses with T_C<>T_x, it was necessary to apply an external magnetic field in ord er to decrease H_c.It was found that non-magnetostrictive metallic glasses with low Curie temperatures (T_C ? 450 K) exhibit the most stable magnetic hysteresis loop parameters.     

Structural relaxation in the CoP-CoNiP system upon low-temperature annealing

The atomic structure of alloys in the CoP-CoNiP system in the initial state and its behavior upon low-temperature annealing is investigated. It is shown that structural relaxation starts at temperatures of 150–200°C and results in local atomic ordering at the network boundaries. Crystals 2–5 nm in size start to undergo nucleation at the boundaries of structural heterogeneities when heated further to 250–300°C. The nanocrystal structure corresponds to the metastable phase delta-Co (ICSD 42684) and the unknown phase Co_{1 ? x} P _x . The estimated diffusion coefficient for CoP alloy is 10^?14 m² s^?1, according to the experimental data.     

Effect of low-temperature annealing upon electrophysical parameters for germanium surfaces cleaved in liquid helium

The surface state localized charge on germanium surfaces cleaved in liquid helium is found to be low. He-vapour heating results in irreversible variations of SS characteristics, such as charge density, increase. These variations are believed to be due to rearrangements of the near surface crystalline structure induced by cleaving and subsequent heating of the samples. The temperature shock arised on cleaving might be responsible for the surface crystalline structure and defect formation. The surface obtained is heterogeneous. Nonuniform surface properties are caused by different energy release and relief geometry which results from different crack advancing conditions over the cleaved surface. The influence of adsorption of foreign atoms on the SS characteristics has been also investigated.     

Effect of thermal annealing on light yield,low temperature thermoluminescence,and time profiles of LuAG:Pr scintillator crystals

Measurements of light yield, low temperature thermoluminescence, and scintillation time profiles, performed comparatively on “as grown” and thermally annealed LuAG:Pr samples, are reported. It is shown that traps play an efficient role in the scintillation of LuAG:Pr, being responsible for the yield decrease and introducing a long component to the time profiles. The trap concentrations in the annealed crystals are lower than in the non-annealed ones, which correlates with the yield enhancement.     

Electrical resistivity study of some lead-borate glasses

We present the results of electrical resistivity measurements performed on 20Fe₂O₃80[3B₂O₃(1?x)PbOxA_uO_v] glasses, with AuOv=K₂O, Ca, As₂O₃ and GeO₂. For a given temperature the electrical conductivity is linearly dependent on the fraction of ferrous ions. The experimental data are well described by using a model involving small polarons.