Units In Glass Network Research Articles

∼2 μm fluorescence and energy transfer characteristics in a highly Tm3+-doped bismuthate glass based on Al2O3 adjustment

In this paper, the glass network of a newly developed bismuthate glass was adjusted and analyzed by changing the Al2O3 content, thus effectively increasing the doping concentration of Tm3+. The fundamental physical and thermal properties including density, molar volume, refractive indices, and characteristic temperatures were systematically investigated, suggesting the B2O3/Al2O3 anomaly ratio of the prepared host glass is 35%/10%. Various glass network units were found in the host glasses, so that the flexibility of the glasses was enhanced, which is favorable for highly and homogeneously doping of Tm3+ ions. A highly Tm3+-doped bismuthate glass with a concentration of 20.5 × 1020 ions/cm3 was prepared without quenching. Radiative parameters of the presented glass were determined from absorbance spectra. Moreover, relatively large emission cross-section (5.29 × 10−21 cm2) and gain coefficient (10.87 cm-1) were achieved in the prepared highly Tm3+-doped bismuthate glass. Finally, the microparameters for energy transfer processes were calculated by a spectral overlap method. Results show that the presented highly Tm3+-doped bismuthate glass has ideal potential for high gain fibers in ∼2 µm band.

Effect of SiO2/B2O3 Replacements on the Structure, Physicochemical and Electrical Properties of Bi2O3-Containing Glasses

The effect of increasing SiO 2 at the expense of B 2 O 3 on the internal structure of xSiO 2-(40-x) B 2 O 3-60Bi 2 O 3 glass matrix (where x=0, 10, 20, 30 and 40 mole %) was investigated. The glass structure was indicated that Bi 3+ cations are incorporated in the glass structure as pyramidal [BiO 3] and [BiO 6] octahedral units and boron ions are incorporated in BO 3 and BO 4 units. The presence of distorted [BiO 6] octahedral units in the glass network was observed and the degree of distortion was found to be decreased on progressive substitution of B 2 O 3 by SiO 2. The results revealed that increase of SiO 2/B 2 O 3 replacements, led to increase the density, microhardness and chemical durability of the studied glasses. However, the molar volume was decreased. The increase of SiO 2/B 2 O 3 replacements generally decreased the AC conductivity. That decrease may be due to the decrease in distortion of [BiO 6] octahedral units in glass network on progressive substitution of B 2 O 3 by SiO 2. Dielectric constants of the samples are complex, which may be an indication of the distortion (number of free charges or broken bonds) in the network of the glass. The obtained experimental data were argued to the internal structure of glass network and the change of the structure of the samples from pyramidal to octahedral and the presence of boron ions in BO 3 and BO 4 units.

Optical and structural investigation of Sm3+–Nd3+ co-doped in magnesium lead borosilicate glasses

Sm3+–Nd3+ co-doped magnesium lead borosilicate glasses are prepared by using the conventional melt quenching technique. The glasses are examined by optical absorption, Luminescence, FT-IR, Raman spectral technique to study the characteristics of Sm3+ in the present glasses and XRD spectra reveals that these glasses has amorphous nature. Judd–Ofelt intensity parameters, Ωλ are calculated for observed absorption bands of Sm3+ ions. Luminescence spectra recorded with excited wavelength of 355nm, here five luminescence bands are observed in Vis–NIR regions which are due to spectra materials (Sm3+, Nd3+). These results suggested that these glasses are responsible for orange luminescence and might be used in the development of materials for LED's and other optical devices in the visible region. The FT-IR, Raman spectra reveals the nature of bonding situation and different structural units in glass network.

Mid-infrared emissions from Er3+ in Ga2S3–GeS2–Sb2S3 glasses

Emission properties of Er3+ in Ga2S3–GeS2–Sb2S3 glasses at the mid-infrared region were investigated from the viewpoint of their dependence on the concentration of the active ion and the glass composition. In the Judd–Ofelt analysis, no variation in omega parameters were observed when GeS2 was replaced by Ga2S3, while Ω2 increased as Sb2S3 was replaced by Ga2S3. This is due to the structural similarity and difference between the glass network units, GaS4 and GeS4 tetrahedra, and SbS3 pyramid. Clear mid-infrared emissions were observed at 2750 and 4300 nm assigned to the 4I11/2 → 4I13/2 and 4I9/2 → 4I11/2 transitions, respectively. The lifetime of the initial level of the 4.3 μm emission, 4I9/2, rapidly decreased with the Er3+ concentration because of the cross relaxation of this level, which can take place even at considerably low Er3+ concentration. The cross-relaxation processes were suppressed by the increase in the content of Ga2S3 because the solubility of Er3+ ions in the glasses increases with the Ga2S3 content.