Fe对掺钕磷酸盐激光玻璃激光性能的影响

在理论分析的基础上,具体讨论了Fe质量分数小于10-4对1 053 nm处光吸收损耗和Nd3+无辐射跃迁几率的影响规律,发现Fe在1 053 nm处的光吸收损耗和Nd3+无辐射跃迁能量转移都与Fe质量分数成平方关系增长, Fe对1 053 nm光吸收的影响较大而Fe与Nd3+之间的能量转移不足50 Hz。这对生产过程中Fe含量的控制有重要指导意义。     

Fe对掺钕磷酸盐激光玻璃激光性能的影响

 在理论分析的基础上,具体讨论了Fe质量分数小于10^-4对1 053 nm处光吸收损耗和Nd³⁺无辐射跃迁几率的影响规律,发现Fe在1 053 nm处的光吸收损耗和Nd³⁺无辐射跃迁能量转移都与Fe质量分数成平方关系增长, Fe对1 053 nm光吸收的影响较大而Fe与Nd³⁺之间的能量转移不足50 Hz。这对生产过程中Fe含量的控制有重要指导意义。     

Effect of WO3 on the glass transition and crystallization kinetics of borotellurite glasses

Tellurite glasses of the system xWO₃–75TeO₂–(25 ? x)B₂O₃ (0 ≤ x ≤ 25 mol. %) were prepared and studied by differential thermal analysis to explore the effect of WO₃ on their glass transition and crystallization kinetics. The crystallization kinetics was studied under non-isothermal conditions using the formal theory of transformations for heterogeneous nucleation. The crystallization results were analyzed and both the activation energy of the crystallization process and the crystallization mechanism characterized. The phases into which the glass crystallizes were identified by X-ray diffraction. Diffractograms of the transformed material indicate the presence of microcrystallites of α-tellurite, Te_0.95W_0.05O_2.05, Te₂W and B₂O₃ in the amorphous matrix.     

Subsurface damage of Nd-doped phosphate glasses in optical fabrication

We present a destructive method for detecting and measuring subsurface damage of Nd-doped phosphate glasses. An instrument based on the dimple method - a destructive method - was developed. Subsurface damage depth produced in each fabrication procedure was obtained. We extend the surface roughness-subsurface damage relation to Nd-doped phosphate glasses. The constant ratio of subsurface damage and surface roughness was obtained as well. We also analyse the relation of abrasive size and subsurface damage experimentally. From a measurement of the surface roughness or abrasive size, one can obtain an accurate estimate of the damage layer thickness that must be eliminated by polishing or subsequent grinding operations.     

Mössbauer studies of phosphate glasses for the immobilisation of toxic and nuclear wastes

Various iron-containing phosphate glasses were investigated by Mössbauer spectroscopy. Iron was found to occur predominantly as Fe³⁺ in all glasses, and largely occupied sites with distorted octahedral coordination for both redox states. Using a base glass of nominal composition 60 P₂O₅–40 Fe₂O₃ (mol%), stepwise molar replacement of Fe₂O₃ by (0.67 Na₂O?×?0.33 Al₂O₃) increased the redox ratio, Fe²⁺/ΣFe, from 0.13 at 40% Fe₂O₃ to 0.25 at 10% Fe₂O₃. The centre shift increased and quadrupole splitting decreased by up to ～20% over this range, interpreted as a decrease in the average distortion of Fe sites from cubic symmetry, and an increase in average iron coordination. Literature revealed that recoil-free fraction ratio f (Fe³⁺)?/?f (Fe²⁺)?≈?1.3 in iron phosphate glasses, and this was considered when assessing redox. Mössbauer parameters of these and other glasses demonstrated a combination of structural stability and compositional flexibility which makes them so suitable for waste immobilisation.     

Second virial coefficient and mechanical moduli of metallic glasses

The relationship between the bulk, shear moduli and second virial coefficient of amorphous materials is derived according to their dependences with the radial distribution function. Lennard-Jones–Gaussian potential is used to investigate the relationship between second virial coefficient and temperature, where Lennard-Jones potential represents interactions with the nearest neighbor atoms, and Gaussian potential is responsible for the multi-atom interactions including the next nearest neighbor atoms and heterogeneous structures for a metallic glass. The results show that deep potential well formed by Gaussian potential causes a large second virial coefficient at low temperatures, which is very obvious for the larger fragility glasses. The quadratic form relationship of shear modulus and compositions is proposed, and confirmed by the experimental results of Pd_xNi_100−x−20P₂₀ alloy.     

UV-visible and infrared absorption spectroscopic studies of gamma irradiated tungsten-doped lithium phosphate glasses

Ultraviolet-visible and infrared spectroscopic techniques were employed to investigate the undoped lithium phosphate glass and other samples of the same composition doped with varying WO₃ contents. The same spectroscopic properties were remeasured after subjecting the samples to 3 and 6 Mrad doses of gamma irradiation on the measured properties. Such combined analytical techniques are expected to give information about the state of tungsten ions in such lithium phosphate glass and justify the effect of gamma irradiation. The work aims to deduce the radiation-induced defects generated through successive gamma irradiation by optical measurements. Also, the study is expected to realize through IR spectroscopy, the main structural building groups and the influence of tungsten ions within the structural vibrational groups of the studied glasses.     

Yb3+,Er3+离子共掺磷酸盐铒玻璃的Judd-Ofelt光谱参数与光谱性质

研究了含Er3+离子浓度较高(155×1020cm-3)的磷酸盐玻璃中Yb3+敏化离子浓度和Al2O3含量对Er3+离子光谱性质的影响.根据掺Er3+磷酸盐玻璃的吸收光谱,利用JuddOfelt理论计算了强度参数Ωt(t=2,4,6)、Er3+离子的4I132→4I152能级跃迁振子强度、自发辐射几率等光谱参数.用McCumber理论计算了Er3+离子的受激发射截面,结果表明Yb3+离子浓度不影响Er3+离子的受激发射截面,但会影响Er3+离子荧光强度,Yb3+含量越高,Er3+的荧光越强.对掺Er3+磷酸盐玻璃的荧光上转换光谱测试表明,Yb3+含量越高,上转换荧光越强,玻璃上转换主要表现为双光子吸收机理研究了含Er3+离子浓度较高(155×1020cm-3)的磷酸盐玻璃中Yb3+敏化离子浓度和Al2O3含量对Er3+离子光谱性质的影响.根据掺Er3+磷酸盐玻璃的吸收光谱,利用JuddOfelt理论计算了强度参数Ωt(t=2,4,6)、Er3+离子的4I132→4I152能级跃迁振子强度、自发辐射几率等光谱参数.用McCumber理论计算了Er3+离子的受激发射截面,结果表明Yb3+离子浓度不影响Er3+离子的受激发射截面,但会影响Er3+离子荧光强度,Yb3+含量越高,Er3+的荧光越强.对掺Er3+磷酸盐玻璃的荧光上转换光谱测试表明,Yb3+含量越高,上转换荧光越强,玻璃上转换主要表现为双光子吸收机理 关键词： Er3+离子 磷酸盐玻璃 光谱性质 JuddOfelt参数     

Interactions of gamma rays with undoped and Mn-doped sodium phosphate glasses

Ultraviolet and visible spectroscopic measurements were used to investigate prepared undoped and Mn-doped sodium phosphate glasses before and after successive gamma irradiation. The effects of both glass composition and MnO₂ content on the generation of radiation-induced defects were investigated. Undoped sodium phosphate glass shows strong UV absorption, which is attributed to the presence of trace iron impurities present in the raw materials. Mn-doped glasses reveal an additional visible broad band centered at about 500 nm due to Mn³⁺, which has recently been related to the ⁵E_g →⁵T_2g transition. The radiation-induced bands are correlated with the generation of liberated electron–hole pairs during the process of gamma irradiation and the possibility of photochemical reactions especially with trace iron impurities and manganese ions. The intensity and the position of the induced bands are observed to depend on the type and composition of glass, concentration of the dopant and also on the irradiation dose. Manganese ions when present in relatively higher content have been found to show a shielding behavior towards the effects of progressive gamma irradiation causing a retardation of the growth of the induced defects. Infrared and Raman spectra of the undoped and Mn-doped glasses were measured to investigate the structural phosphate groups present and the effect of MnO₂ on the network structure. An ESR investigation was carried out to confirm the state of manganese ions in the prepared sodium phosphate glasses.     

Mechanism and modelling of aluminium nanoparticle oxidation coupled with crystallisation of amorphous Al2O3 shell

The oxidation of aluminium nanoparticles coupled with crystallisation of amorphous alumina shell is investigated through the thermogravimetric analyser and differential scanning calorimetry (TGA-DSC) and the transmission electron microscope (TEM). The thermogravimetric (TG) curves show stepwise shapes with temperature increase and could be divided into four stages. The reaction at the second stage is complex, including the simultaneous crystallisation of amorphous alumina (am-Al₂O₃) and Al oxidation. The crystallisation of am-Al₂O₃ promotes the reaction through generating fast diffusion channels, like micro-cracks and grain boundaries in the oxide shell to accelerate the ionic diffusion. An enhancement factor (f_react), which follows a power-law formula with the crystallisation rate, is introduced to quantify the impact of crystallisation on reaction. With heating rate increase, the second stage of TG curves shifts to the high temperature regime and the total weight gain at the second stage decreases slowly. A crystallisation-reaction model is constructed to fit and predict the weight gain after derivation of diffusivities and crystallisation kinetics. Modelling indicates that with heating rate rise, the mass increment at the second stage of TG curves decreases owing to the reduced reaction time, although the reaction is accelerated. The shift of TG curve to higher temperature is due to the polymorphic phase transition. Actually the derived kinetics of the crystallisation of amorphous alumina indicates that the polymorphic phase transformation mechanism works mainly below the heating rate of 3 K s^–1. At higher heating rate, the melting of Al takes place firstly and the crystallisation of am-Al₂O₃ follows to enhance the ionic diffusion. Therefore, when the heating rate is fast during ignition or combustion, the Al nanoparticles undergo both the melting of Al and the polymorphic phase transition of am-Al₂O₃ to accelerate the reaction.     

UV-visible and infrared absorption spectra of gamma irradiated CuO-doped lithium phosphate, lead phosphate and zinc phosphate glasses: A comparative study

Undoped and CuO-doped lithium phosphate, lead phosphate and zinc phosphate glasses were prepared. UV-visible and infrared absorption spectra of the prepared samples were measured before and after successive gamma irradiation. Experimental optical spectra of the undoped samples reveal strong UV absorption bands, which are attributed to the presence of trace iron impurities in both the lithium and zinc phosphate glasses while the lead phosphate glass exhibits broad UV bands due to combined absorption of trace iron impurities and divalent lead ions. The CuO-doped glasses reveal an extra broad visible band due to Cu²⁺ ions in octahedral coordination. The effects of gamma irradiation have been analyzed for both the sharing of all constituent components including trace iron impurities. Infrared absorption spectra of the prepared samples were investigated by the KBr disk technique. The FTIR spectra reveal main characteristic absorption bands due to different phosphate groups. The IR spectra are observed to be slightly affected by the increase of CuO in the doping level (0.2-3%) indicating the stability of the main network units.     

稀土掺杂P2O5-Al2O3-BaO玻璃的制备及其结构研究

稀土掺杂磷酸盐玻璃具有优异的光学和光谱特性,在激光介质、有色滤光材料等领域中有着重要的应用。在P2O5_Al2O3_BaO_Sm2O3(PABS)玻璃形成能力研究的基础上,借助MAS NMR、红外光谱等分析手段,研究了玻璃的结构、玻璃组成与热处理等对玻璃结构的影响。结果表明:不同组成PAB(S)玻璃的31P MAS NMR谱在-20ppm~-25ppm范围内均存在单一的特征信号峰,对应于磷氧多面体[PO4]的Q2型结构;在18ppm、-12ppm和-36ppm处27Al的MAS NMR谱的三个特征信号峰分别对应于27Al的[AlO5][、AlO6]、[AlO6]配位结构,稀土离子的掺入以及热处理均使得[AlO6]向[AlO5]转变;玻璃的网络结构主要由Q2型[PO4]、[AlO5]和[AlO6]构成,并P_O_P、P_O_Al的形式相连接。玻璃在1383 cm-1处出现的吸收峰可能是玻璃结构中形成了P_O_Sm键所致。     

Origin of excess low-energy vibrations in densified B2O3 glasses

Low-temperature experiments of Raman scattering and heat capacity have been performed in a B₂O₃ glass, pressure quenched from 1200 °C in order to obtain the density as largest as possible (ρ = 2373 kg/m³). When compared to those of compacted B₂O₃ glasses having smaller density, the Raman spectrum of this glass exhibits a strong decrease of the intensities of the Boson peak and the band at 808 cm^?1, both the features being determined by the decrease of the boroxol ring population. Moreover, the Boson peak exhibits a large shift to 68 cm^?1 (from 26 cm^?1 observed in normal vitreous B₂O₃). The high atomic packing of the glassy network also leads to a marked decrease of the excess heat capacity over the Debye T³-behaviour characterizing the crystal. The density g(ν) of low-frequency vibrational states has been assessed by using the low-frequency Raman intensity to determine the temperature dependence of the low-temperature heat capacity. The observations performed over a wide range of glass densities are compared to the predictions of theoretical models and computer simulations explaining the nature of the Boson peak. Consistency with the results of a simulation study concerning the vibrations of jammed particles leads to evaluate a nanometre length scale which suggests the existence of poorly packed domains formed from several connected boroxols. These soft regions are believed to be the main source of low-frequency optic-like vibrations giving rise to the Boson peak.     

Glass forming regions and dielectric properties of new phosphate glasses

The glass forming regions have been determined in the systems P₂O₅-A₂O-MO (A = Li, Na; M = Cu, Cd), P₂O₅-Bi₂O₃-Li₂O and P₂O₅-Bi₂O₃-ZnO. The largest vitreous domain has been found in the ternary diagram P₂O₅-Bi₂O₃-ZnO. The variation of the dielectric constants has been followed inside the glass regions. ε'_r increases with increasing amount of alkaline oxides and substantially diminishes with increasing percentage of either CuO or CdO.     

Influence of heat treatment on structure and some physical properties of lithium boro-niobate glass

The glass composition (90?mol% Li₂B₄O₇–10?mol% Nb₂O₅) was prepared by the melt quenching technique. The quenched sample was heat treated at 480°C, 545°C and 630°C for 5?h and heat treated at 780°C with different time. The times were 5, 10, 15, 20, 28, and 36?h. The glass and glass ceramics were studied by differential thermal analysis (DTA), X-ray diffraction (XRD), and dc conductivity as a function of temperature. Lithium niobate (LiNbO₃) and lithium diborate (Li₂B₄O₇) were the main phases in glass ceramic addition to traces from LiNb₃O₈. Crystallite size of the main phases determined from the X-ray diffraction peaks are in the range <100?nm. The fraction of crystalline (LiNbO₃) phase increases with increase the heat treatment temperature and time. The relation between physical properties and structure were studied.     

(ZnO)_(1-x-y)(P_2O_5)_x(B_2O_3)_y玻璃的环境稳定性和红外光致发光(英文)

Er3+掺杂的(ZnO)1-x-y(P2O5)x(B2O3)y玻璃具有优良的光学性质。沸水煮沸实验结果表明,该类玻璃具有较高的环境稳定性。与(Er2O3)z(ZnO)1-x-z(P2O5)x-z类玻璃相比,Er3+掺杂的该类玻璃在1.5μm峰值位置的光谱半峰全宽超过110 nm,而且具有较高的猝灭浓度。     

The Physical Properties of P2O5–Sm2O3–MnO2 Glass System

Phosphate glasses doped with samarium oxide have been made using the melt quenching technique. The density of the glass was determined using the Archimedes method while the Vickers hardness was measured using a micro-vicker tester. Both density and hardness have shown an increasing trend with the addition of a small amount of Sm₂O₃. The refractive index was characterized using UV-visible spectroscopy and the Sellmeier fitting equation was used to verify the result. The refractive index was found to vary from 1.972 to 1.807 depending on the wavelength and well agreed with the fitting curve     

Al-Ni-RE非晶合金的晶化行为和热稳定性

本文制备了一系列Al-Ni-RE (RE=La, Ce, Y) 非晶合金薄带, 利用差示量热扫描仪和X射线衍射仪考察了非晶合金的晶化行为和初生相, 并分析了其与合金成分和原子特性间的关系. 结果表明: 在拓扑不稳定参数λ以有效原子半径修正为λ'后, 每一Al-Ni-RE非晶合金体系可由其两个临界值划分为纳米晶、纳米玻璃和玻璃三类; Al-Ni-RE非晶合金的晶化开始温度和混合焓与λ'成良好的线性关系, 即λ'能很好的表征Al基非晶合金的热稳定性. 关键词： Al基非晶 玻璃转变 初生相 热稳定性     

Ag_2O胶体粒子的自组装单层膜和多层膜

本文制备了Ａｇ２Ｏ胶体粒子的自组装单层膜和多层膜。运用接触角测量、红外吸收光谱和紫外可见吸收光谱等手段证实了Ａｇ２Ｏ胶体粒子能够组装在具有羧基的基底上,在有１,１８ 十八烷基二羧酸做为交联剂的情况下还可形成自组装多层膜