Tellurite Glasses

The boundaries of regions of glass-forming compositions were determined in binary tellurite systems with alkali, alkaline-earth, and heavy-metal oxides, and in the ternary systems TeO₂-WO₃-Ta₂O₅, TeO₂-WO₃-BaO, TeO₂-WO₃-Bi₂O₃, and TeO₂-WO₃-Tl₂O. On the basis of a structural interpretation of liquid immiscibility in binary oxide systems and of X-ray diffraction investigation of the structure of tellurite glasses, a crystallochemical interpretation of glass formation is proposed, as well as a method for calculating the modifier-poor boundaries of the regions of glass-forming compositions in binary systems. An investigation of the crystallizability, density, optical constants, spectral transmission characteristics, and chemical durability of the tellurite glasses as functions of their chemical compositions has led to the development of a new flint-type optical glass, with n _d= 2.1608 and v = 17.4, possessing a high chemical durability and resistance to devitrification.     

Unusual Immiscibility Structures in Tellurite Glasses

Unusual droplet microaggregates are observed in TeO₂-rich glasses of the systems TeO₂–B₂O₃, TeO₂–GeO₂, TeO₂–B₂O₃–GeO₂, and TeO₂–GeO₂–V₂O₅. A decrease of the TeO₂ content is established in the aggregates in comparison with the matrix. Their appearance is related to the process of metastable liquid-phase separation at high viscosity of the melts.     

Electrical Conductivity of Silver Vanadium Tellurite Glasses

We have investigated mixed electronic-ionic conduction in 0.5[ x Ag₂O·(1 − x )V₂O₅]–0.5TeO₂ glasses, where the Ag₂O amount varies over a range of 5–40 mol%. The glass samples have been prepared by quenching the melt. The ac conductivity has been measured at frequencies from 10 Hz to 100 kHz and temperatures of 300–425 K. The data indicate that the conduction mechanism changed from being predominantly electronic to ionic for Ag₂O contents of >27.5 mol%. This transition is due to the change in glass structure, which affects both electronic- and ionic-transport properties. The electronic dc conductivity results have been analyzed in terms of a small polaron-hopping model.     

Tellurite Glasses for Broadband Amplifiers and Integrated Optics

The present investigation discusses the advantage of using RE-ion-doped (Nd³⁺, Tm³⁺, and Er³⁺) TeO₂ glasses for developing fiber and planar broadband amplifiers and lasers. The spectroscopy of RE-ion-doped fibers and glasses is discussed along with the thermal properties of glass hosts. The results of emission from the ³H₄ level in single-mode Tm³⁺-doped tellurite fiber show that the emission band overlaps with Er³⁺ emission from the ⁴I_13/2 level and Nd³⁺ emission from the ⁴F_3/2 level in silicate and tellurite glasses, thereby enabling the development of amplifiers and lasers between 1350 and 1650 nm. Recent results using Z-scan measurements of nonlinear refractive index and absorption demonstrate that the third-order nonlinearity in undoped TeO₂ glasses is of the order of 2 × 10⁻¹⁵ to 3 × 10⁻¹⁵ cm²·W⁻¹ between 1300 and 1550 nm. These results are briefly discussed in view of an amplifier operation combined with ultrafast all-optical switching.     

Sellmeier Coefficients and Chromatic Dispersions for Some Tellurite Glasses

Sellmeier coefficients are necessary to optimize the design parameters of optical devices. These coefficients are computed for binary tellurite glasses to find the chromatic dispersion behavior at any wavelength, particularly at the optical windows of optical fiber communication systems and femtosecond technology. A single-oscillator DiDomenico and Wemple's dispersion equation is not sufficient to represent accurately the measured refractive indexes throughout the transmission range. As a minimum, a two-pole Sellmeier equation is necessary to represent the data more accurately. Both the average electronic absorption band gap and the lattice absorption frequency, lying in the UV and IR region, respectively, affect the refractive indexes and their dispersion. Various other optical properties are discussed. A single-oscillator dispersion equation is unable to verify the existence of zero-dispersion wavelength.     

掺Er3+碲酸盐玻璃热稳定性的改进

制备了掺Er3+ -TeO2-ZnO-Na2O-Nb2O5和TeO2-PbO-B2O3系统玻璃,测定了玻璃的热稳定性和吸收光谱,在碲-锌-钠多组分玻璃中具有不同的玻璃转变温度Tg和开始析晶温度Tx,按照Hruby's参数HR=(Tx-Tg)/(Tl-Tc);(Tx-Tg)越大则玻璃稳定性越好,在TeO2-ZnO-Na2O系统玻璃中ZnO含量增加则(Tx-Tg)增大,加入少量(小于10%(摩尔分数))Nb2O5,Pb0使(Tx-Tg)变大,玻璃的热稳定性变好.     

High-Performance Integrated Optics with Tellurite Glasses: Status and Prospects

Tellurite glasses have long been recognized as interesting materials for fiber and integrated optics, but it is only recently that the first steps toward high-performance planar devices have been taken. This study reviews the opportunities for planar tellurite devices, the current state of the art of planar waveguide devices, and considers the areas of research required to move the materials platform to the level of maturity needed to realize its promise.     

Spectroscopic Analysis of the Structure and Properties of Alkali Tellurite Glasses

Structural development of tellurite glasses with the addition of Li₂O and Na₂O has been studied using infrared, Raman, and X-ray photoelectron spectroscopies. The increase in intensity of the peak at 755 cm⁻¹ in the infrared spectra as compared to the peak at 620 cm ⁻¹ suggests the transformation of TeO₄ building units to TeO₃ pyramids with the addition of alkali oxide. Proposed structural change is further supported by the strong compositional dependence of the 755-cm⁻¹ peak in the Raman spectra as well as by the formation of a shoulder in the O 1 s peak of X-ray photoelectron spectra. In contrast to alkali silicate glasses, formation of nonbridging oxygens with the addition of alkali oxide is not observed.     

Characterization of New Categories of Bioactive Based Tellurite and Silicate Glasses

New types of tellurite glass ceramics were prepared and studied from the viewpoint of bioactivity. The obtained results were compared with those of silicate glass ceramics. The crystallization behaviors of both silicate and tellurite glass ceramics with equal ratio of CaO/P₂O₅ were investigated. The silicate glass samples were transformed to glass ceramics by a thermal treatment process. While the tellurite glass ceramics were directly obtained without any thermal treatment. The microstructure of these materials was characterized by X-ray diffraction (XRD), Fourier transform infrared absorption spectroscopy (FTIR) and a scanning electron microscope (SEM) equipped with an energy dispersive spectrometer (SEM/EDX). The results revealed clear proof that TeO₂ promoted the nucleation and crystallization processes which led to the formation of different crystalline bio-phases. While the silicate glasses showed a much lower degree of crystallinity than that presented by the tellurite glass ceramics. The crystals of tellurite containing glass were needle- like morphology, which is attributed to the one-dimensional rapid growth of the apatite-tellurite phase. On the other hand, a particle-like morphology is shown in the silicate glass matrix. Bioactivity of the glasses in simulated body fluids (SBF) was investigated. Tellurite containing glass ceramics showed a better bioactivity during the in vitro test than that of the silicate one. This was attributed to a great analogous between the morphology of crystals of tellurite glass and the morphology of hydroxyapatite in human bone, since both possess a needle-like morphology.     

Kinetics of Enthalpy Relaxation at the Glass Transition in Ternary Tellurite Glasses

The kinetics of enthalpy relaxation (recovery) at the glass transition in x K₂O·(20− x )MgO·80TeO₂ glasses has been examined from heat capacity measurements using differential scanning calorimetry to clarify the features of the structural relaxation in ternary TeO₂-based glasses. Ternary glasses such as 10K₂O·10MgO·80TeO₂ show high thermal resistance against crystallization compared with binary glasses. The degree of fragility m estimated from the activation energy for viscous flow E _η and the glass transition temperature T _g is m = 55–62, indicating a fragile character in TeO₂-based glasses. Large heat capacity changes of 43.1–48.2 J·mol⁻¹·K⁻¹ are also observed at the glass transition. The activation energy for enthalpy relaxation Δ H is evaluated from the cooling rate dependence of the limiting fictive temperature, and values of Δ H = 897–1268 kJ·mol⁻¹ are obtained. Negative deviation from additivity in Δ H is also observed. Values of the Kovacs–Aklonis–Huchinson–Ramos (KAHR) parameter θ estimated from Δ H and T _g are 0.33–0.42 K⁻¹. It has been proposed that ternary glasses have more homogeneous and constrained glass structure compared with binary glasses.     

Fabrication of Transparent Tellurite Glasses Containing Potassium Niobate Crystals by an Incorporation Method

To fabricate transparent oxide glasses containing ferroelectric KNbO₃ crystals, a new method in which KNbO₃ particles are directly incorporated into TeO₂─K₂O─Nb₂O₅ glasses has been developed. Transparent TeO₂-based glasses containing KNbO₃ crystals with a diameter of ∼ 10 μm have been first successfully fabricated by adjusting temperature and time for incorporation. A small difference in the refractive indexes, n , between TeO₂-based matrix glasses ( n = 2.0) and incorporated KNbO₃ crystals ( n = 2.21) is a significant reason for the transparency. This new method is applicable for the fabrication of new transparent glasses containing other functional materials with high refractive indexes.     

铋碲酸盐玻璃中三价铕离子多通道跃迁发射的三维荧光光谱分析

在初步观察到三价铕离子多通道跃迁发射的基础上,测定了Eu3 掺杂铋碲酸盐玻璃的三维荧光光谱。三维光谱显示,罕见的铕离子5D3、5D2、5D1向下能级跃迁的蓝光和绿光多通道发射在较宽的激发范围内均可被有效地观察和记录到。通过对铕离子能级结构和玻璃基质声子能量的综合分析,认定最大声子能量较低是铋碲酸盐玻璃中获得铕离子多通道跃迁发射主要原因。激发光谱表明,紫色光源可有效激发样品,获得由蓝到红的多峰发射;对于始于5D0态的Eu3 常规发射,氩离子激光器,紫色、蓝色和绿色激光二极管及发光二极管均为有效泵浦光源。     

硼硅酸锌玻璃的制备及其发光特性

由于发光玻璃独特的透明性,在激光、光学放大器、光通讯、储能和显示等光电子领域有着广泛的应用.本文利用高温固相法制备出了新型硼硅酸锌:铕掺杂的硼硅酸锌玻璃,讨论了掺杂离子浓度对玻璃发光特性的影响.结果表明Eu2+掺杂的硼硅酸锌玻璃在250～400 nm波长范围可以被很好地激发,有很宽的激发波长范围,发射谱为一个宽带峰,位于450 nm.掺杂不同浓度的Eu2+的硼硅酸锌发光玻璃的激发光谱有所不同,随着掺杂Eu2+浓度的增加,荧光强度增强,但发射光谱峰位置基本没有变化.另外,Eu2+掺杂硼硅酸锌玻璃较易合成,是一种很好的蓝色发光材料,具有较大的应用价值.     

Refractive-Index Dispersion of Tellurite Glasses in the Region from 0.40 to 1.71 μm

The refractive index of binary tellurite glasses with various modifiers was measured down to the fifth decimal place in the wavelength range of 0.40–1.71 μm using the minimumedeviation method. An empirical equation based on the single-oscillator Drude–Voigt dispersion equation. n _d²= A·Nf λ₀²+ B , is obtained, where n _d is the refractive index at 0.5876 μm, N is the number of molecules in a unit volume, f is the average oscillator strength, λ₀ is the average resonance wavelength, and A and B are constants. The refractive index n _d of tellurite glasses is substantially determined by the resonance wavelength at the ultraviolet region, which is affected by the main constituent, TeO₂.     

Tm3+离子浓度对碲酸盐玻璃热稳定性及光谱性能的影响

用高温熔融冷淬法制备Tm3+离子掺杂75TeO2-20ZnO-5La2O3碲酸盐玻璃,运用差示扫描量热仪(DSC)分析了玻璃样品的热稳定性,结果表明样品均具有良好的热稳定性.根据紫外-可见-近红外分光光度计测量得到的玻璃吸收光谱,运用Judd-Ofelt理论,计算了Tm3+离子在碲酸盐玻璃中的Judd-Ofelt强度参数、自发辐射概率A、荧光分支比β和辐射寿命ΤR等光谱参数.当掺杂浓度为0.8mol％时,玻璃热稳定性好,3H4的荧光寿命最长,为0.285ms,有望成为一种理想的S波段宽带光纤放大器用基质材料.     

Structural Role of Zinc Oxide in Silica and Soda-Silica Glasses

The structures of amorphous zinc silicate and sodium zinc silicate have been studied using the molecular dynamics computer simulation technique. Results showed that bond lengths and coordination numbers for the individual atomic species fit within the range of results from a number of crystalline and glassy silicates. Discrete ZnO₄ tetrahedra were seen to exist to a higher degree in the sodium zinc silicate system due to charge compensation from neighboring sodium atoms. Simulation results are also compared to EXAFS data of low concentrations of zinc oxide in silica and sodium silicate glasses. The local environment of oxygen in the simulated systems is also discussed.     

Alkali Magnesium/Zinc Silicate Glasses with Low Rayleigh Scattering

The Rayleigh scattering of silicate glasses (M₂O-RO-SiO₂, M: Na and K, R: Mg, Ca, and Zn) was measured. Soda magnesium silicate (NMS) glasses exhibited the smallest scattering intensity. It is comparable with that of soda aluminosilicate (NAS) glass, one of the candidates for use in fabricating ultralow-loss fibers. The scattering intensity decreased with decreasing SiO₂ content, and NMS glasses with 60 mol% of SiO₂ are still stable against crystallization. It is concluded that NMS is a new candidate for ultralowloss fiber use.     

Density of Bismuth Boro Zinc Glasses Using Machine Learning Techniques

Journal of Inorganic and Organometallic Polymers and Materials - Machine learning techniques have been employed to predict the glass densities of...     

Improved Impact Resistance in Soda-Lime-Silica Glasses Through Zinc Oxide Substitutions

Several soda-lime-silica glasses were melted in which up to 8.52 wt% zinc oxide was substituted for calcium and magnesium oxide. Sonic Young's modulus and Charpy impact resistance measurements were made. The results indicated that an increase of 8.52 wt % zinc oxide reduced the Young's modulus by 9.0% and increased the impact resistance of the soda-lime-silica glass by 4.1% .