Broadband 1.53 μm emission in Er^(3+)-doped Ga-Bi-Pb-Ge heavy metal oxide glasses

We investigated the thermal stability and spectroscopic properties of the 1.53 μm emission from ^4I13/2→^4I15/2 transition of Er^3＋ ions in Er^3＋/Yb^3＋-codoped Ga-Bi-Pb-Ge heavy metal oxide glass for use in broadband fiber amplifiers. It was noted that the addition of GeO2 effectively enhanced the thermal stability of the heavy metal oxide glass studied. The emission peak located at approximately 1530 nm with a full width at haft-maximum of approximately 58 nm. The measured lifetime and the calculated emission cross-section of this transition were -3.2 ms and -10.3×10^-21 cm^2, respectively. As a result, Ga-Bi-Pb-Ge heavy metal oxide glasses were assumed to be potential host material for the 1.53 μm broadband optical fiber amplifiers.

Corrosion by a Heavy Metal Oxide Glass

Melts of lead bismuth gallate compositions are highly corrosive and attack on crucibles of different materials. In the present study, corrosion by a base glass (50PbO-30Bi2O3-20Ga2O3 in mole fraction) melted using different crucibles and the effect on UV-VIS and IR edges were studied. By melting the base glass in platinum/2% rhodium, gold zirconia and alumina crucibles showed less effect on the IR edge and therefore shifted the infrared edge to longer wavelength, whereas silica crucible contaminated the glass, causing a severe deterioration in the infrared and hence shifted infrared edge to much shorter wavelength. In the UV-VIS region, base glass melted in platinum/2% rhodium crucible shifted the edge to the longest wavelength whereas silica crucible shifted the edge to shorter wavelength. The contaminants from gold, zirconia and alumina crucibles caused the UV-VIS edge of the base glass to lie between the two extremes of Pt/2% Rh and SiO2 crucibles. The glasses melted in above mentioned crucibles were also characterized with inductively coupled plasma spectroscopy (ICP) analysis to measure the level of contamination from the crucibles. Depending upon crucible used, the colors of glasses obtained ranged from red to yellow.

Optical properties and irradiation resistance of novel high-entropy oxide glasses La_(2)O_(3)-TiO_(2)-Nb_(2)O_(5)-WO_(3)-M_(2)O_(3)(M=B/Ga/In)

A new class of high-entropy oxide glasses 20LaO_(3/2)-20TiO_(2)-20NbO_(5/2)-20WO_(3)-20MO_(3/2)(M=B/Ga/In)were designed and successfully fabricated by aerodynamic containerless processing.The results show that one can control the properties and increase the functionality of glass by changing the type of M.The Vicker's hardness reaches the highest value of 6.45 GPa for glass M=B.The best thermal stability and the glass forming ability,measured using the glass-transition temperature T_(g) and the temperature gap ΔT respectively,are found in glass M=In,with T_(g)=740℃ and ΔT=72℃.The optical properties show that the as-prepared glasses exhibit good transparency and high refractive index.Especially for glass M=In,its transmittance reaches almost 78% from visible to IR region,and the value is nearly unchanged after electron beam irradiation,indicating good irradiation resistance of this high-entropy oxide glass.Furthermore,the glass M=In has the highest refractive index(n_(d)=2.46) and low wavelength dispersion(v_(d)=45.6).These results demonstrate that the conceptual design of high-entropy materials is adaptable to high performance oxide glasses,which should be promising host materials for optical applications such as smart phones with digital cameras and endoscopes.

The effect of Nb_(2)O_(5)on fast neutron removal cross section,optical,and structural properties of some calcium borate oxide glasses containing Bi^(3+)ions

Background In recent years,the preparation of transparent glass in the visible region has led to the development of radiation shielding materials with measuring structure and optical properties.Also,the study on the interaction of neutron radiation with matter is important in the field of radiation protection.Purpose Preparation of transparent calcium and bismuth borate oxide glasses containing Nb^(5+)ions can be used as a neutron radiation shield and determine refractive index with different methods for this glass.Methods Niobium bismuth borate glasses with composition 60B_(2)O_(3)–20CaO–(20−x)Bi_(2)O_(3)–xNb_(2)O_(5),where(x is in mol%,0≤x≤10),have been prepared using conventional melt-quenching technique;the structure of each sample was studied by XRD,FTIR,and UV spectra chart analysis.Results XRD and FTIR showed that all glass samples were highly homogeneous and had structured with short-rangeorder/amorphous solids.The refractive index of each sample was estimated by charts of UV–Vis and FTIR,in addition to an empirical method,and we obtained values very close to each other.The refractive index values are relatively high,so this glass can be used in nonlinear studies as well as luminescence characterization.The macroscopic fast neutron removal cross sections(R/ρ)have calculated,for all samples,and the highest value was in sample containing 2.5%niobium pentoxide.Conclusion Bismuth borate glass containing a few niobium pentoxide can be used as a protective shield of neutrons.

Er^3＋ and Yb^3＋ Codoped Phosphate Laser Glass for High Power Flashlamp Pumping

A novel yb^3＋-Er^3＋ codoped phosphate glass for high power flashlamp pumping and high repetition rate laser at 1.54μm, designated EAT5-2, is developed. The weight-loss rate of is 1.3 × 10^-5 gcm^-2h^-1 in boiling water, which is comparable to Kigre＇s QX-Er glass. Some spectroscopic parameters are analysed by Judd-Ofelt theory and McCumber theory. The emission cross section is calculated to be 0.73 × 10^-20 cm^2. The thermo-mechanical properties of EAT5-2 are modified after an ion-exchange chemical strengthening process in a KNO3/NaNO3 molten salt bath. The thresholds for optical damage from the flashlamp pumping are tested on glass rods. A repetition rate of 15 Hz is achieved for chemically strengthened glass. The laser experimental results at 1.54 μm from flashlamp pumping are also reported.

STUDY ON Na_2O-GeO_2-SiO_2-PbO GLASSES USED AS THE CLADDING MATERIALS OF HOLLOW WAVEGUIDES FOR TRANSMITTING CO_2 LASER

In this paper a new kind of mid - infrared fiber material is reported. The reflective coefficients (R) of glasses in the system Na2O - ZnO - GeO2-SiO2-PbO have been measured-the refractive index becomes less than unity at 1180 - 900cm-1 range because of the existence of anomalous dispersion. The optical losses of hollow waveguides were calculated,the predicted losses at 940cm-1are 0. 65 and 0. 081B/ m as the inner diameter of fiber is 0. 5 and 1. 0mm respectively. The glasses can be used as the cladding materials of hol-low waveguides for transmitting CO2 laser from the measurements of characteristic temperatures, coefficient of expansion and chemical durability.

INFLUENCE OF Sb_2O_3 AND PbO CONTENT ON GLASS PROPERTIES OF SiO_2-BASED FOR HOLLOW WAVEGUIDES

The reflective spectra of two glass systems of Na2O-ZnO-GeO2-SiO2-PbO(Sb2O3) were measured to study the effects of PbO and Sb2O3 on properties in SiO2-based glasses. The infrared reflective coefficients and anomalous dispersion regions change with the content of PbO and Sb2O3 respectively, furthermore the refractive indices (nr) of glasses are 0. 81 and 0. 84 at the wavelength of CO2 laser (940cm-1). The glasses of two systems can be used as the cladding materials of hollow waveguides for transmitting CO2 laser.

Structure-Property Relations in xWO3-0.31P2O5-0.31B2O3-（0.38-x）Cs2O （0.01 ≤ x ≤0.28） Glasses by IR, UV and EPR Spectroscopic Studies

Glasses in the series of xWO3-0.31P2O5-0.31B2O3-（0.38-x）Cs2O （0.01 ≤ x ≤0.28） （G1-G4： x= 0.01, 0.1, 0.19, 0.28） were prepared by sol-gel method. Glassy phase in the samples were ascertained by powder X-ray diffraction pattern. Differential scanning calorimetry （DSC） traces of the samples show glass transition temperature Tg, in the range 247-253 ℃. IR spectra at 300 K of G1-G4 show the presence of [WO6], [WO4], [PO4]^3-, [PO3]^2-, [BO4]^＋, [BO3] units in the glass matrix. Observed electron paramagnetic resonance （EPR） lineshapes show two signals with very different intensities which are associated with W^5＋ （5d^1） and Mo^5＋ （4d^1） （impurity） paramagnetic sites. Signal with values ofg factors in the range 1.68 〈 g⊥ 〈 1.72 and 1.58 〈 gⅡ 〈 1.62 are due to W^5＋ ions present in axially distorted octahedral symmetry. The optical absorption spectra show that the W^5＋ ions have pyramidal coordination, involving a tungstyl ion WO^3＋ （C4v symmetry）. EPR and optical studies suggest the existence of blocks of octahedra linked by tungsten clusters.

Effect of Annealing Duration and Substrates on Structure and Property of Vanadium Dioxide Films

Using the oxidation method from vanadium metal thin films by magnetron sputtering, under the fixed annealing parameters of temperature（400 ℃） and oxygen pressure（103 Pa）, we fabricated a series of vanadium dioxide thin films through the change of annealing durations or substrates（quartz glass or AZOcovered glass）. Characterization of the thermochromic properties together with the X-ray diffraction（XRD） and field emission scanning electron microscopy（FE-SEM） indicates that appropriate annealing duration is a key factor to obtain pure VO2 films and AZO-covered glass is more suitable to obtain the VO2 films with high visible transmittance, good crystallinity and larger near-infrared switching efficiencies（maximum 34% at 2000 nm） compared with the substrate of quartz glass. However, VO2 films on quartz glass exhibit narrower loop（7 ℃） with smart reversible response to temperature. Depth profile XPS spectra further indicate that for the films fabricated on quartz glass from thicker V metal films, the existence of low valence vanadium oxides is inevitable and leads to a lower transmittance in the region of visible light.

Preparation and Performance of Magneto-optical Glasses Doped with Tb^(3+)/Dy^(3+)

In order to increase the content of rare-earth oxides in magneto-optical glass and improve the Verdet constant, the rare-earth doped ternary Ga2O3-B2O3-SiO2（GBS） system magneto-optical glasses were prepared by the melt quenching technique. The infl uence of Tb3＋ and Dy3＋ ions on the structure of GBS glasses was investigated using FTIR, DSC and Faraday rotations. The experimental results showed that the content of rare-earth oxides in the glasses with the double incorporation of Tb2O3 and Dy2O3 was higher. The crystallization parameter β achieved the maximum 0.48 with Tb3＋/Dy3＋ content of 35mol%. Terbium oxide existed mainly in [TbO3] units in the glasses and [TbO4] units were converted into [TbO3] with increasing Tb2O3 content. As Ga3＋ ion is larger than B3＋ ion in radius, leading to an increasing of the glass network gap and improvement in the ability of accommodating rare earth ions, Verdet constant increased.

Synthesis of praseodymium trioxide doped lead-boro-tellurite glasses and their optical and physical properties

This paper presents the influence of TeO_(2) on the optical and physical properties of rare earth ion Pr^(3+) doped 75PbO-(24-x)B_(2)O_(3-x)TeO_(2)-1Pr_(2)O_(3) glass matrix.Using the absorption coefficient measurements,optical band gap energies of the studied glasses are estimated.Oxide ion polarizability,refractive index,optical basicity,reflection loss and transmission coefficient are discussed and reported for the investigated glasses.Physical parameters like the optical dielectric constant,polaron radius,interatomic separation,molar refraction and the metallization criterion are also studied through molar density and molar volume.The FTIR analysis reveals the shift of the band appearing at 1029 to 870 cm^(-1) because of the high concentration of PbO(75 mol% in the present glass)in the matrix.The Pb-O-B linkage is considered to be the important in the network structure of these glasses.For the present glasses metallization parameter values are<1.The polarizability values are high but decrease with increasing value of TeO_(2) concentration.This may be due to densification of restricted or localized states caused by the creation of dangling bonds.

Plasticityimprovement of a Zr-based bulk metallic glass by micro-arc oxidation

Mciro-arc oxidation（MAO）was used to coat porous films on the surface of a Zr-based bulk metallic glass sample.The compressive test results indicated that,compared with the as-cast sample,the MAO treated one exhibited higher deformation capacity,associated with multiple shear bands with higher density on the side surface and well-developed vein patterns with smaller size on the fractured surface.The pore in the MAOed film and the matrix/coating interface initiated the shear bands and impeded the rapid propagation of shear bands,thus favoring the enhanced plasticity of the MAO treated sample.The obtained results demonstrated that MAO can be considered as an effective method to finely tune the mechanical performance of monolithic bulk metallic glasses.

Photoanode Activity of ZnO Nanotube Based Dye-Sensitized Solar Cells

Vertical ZnO nanotube （ZNT） arrays were synthesized onto an indium doped tin oxide （ITO） glass substrate by a simple electrochemical deposition technique followed by a selective etching process. Scanning electron microscopy （SEM） showed formation of well-faceted hexagonal ZNT arrays spreading uniformly over a large area. X-ray diffraction （XRD） of ZNT layer showed substantially higher intensity for the （0002） diffraction peak, indicating that the ZnO crystallites were well aligned with their c-axis. Profilometer measurements of the ZNT layer showed an average thickness of -7 μm. Diameter size distribution （DSD） analysis showed that ZNTs exhibited a narrow diameter size distribution in the range of 65-120 nm and centered at -75 nm. The photoluminescence （PL） spectrum measurement showed violet and blue luminescence peaks that were centered at 410 and 480 nm, respectively, indicating the presence of internal defects. Ultra-violet （UV） spectroscopy showed major absorbance peak at ,-348 nm, exhibiting an increase in energy gap value of 3.4 eV. By employing the formed ZNTs as the photo-anode for a dye-sensitized solar cell （DSSC）, a full-sun conversion efficiency of 1.01% was achieved with a fill factor of 54%. Quantum efficiency studies showed the maximum of incident photon-to-electron conversion efficiency in a visible region located at 590-550 nm range.