铁磷酸盐玻璃析晶的拉曼光谱及显微分析

为研究热效应对铁磷酸玻璃结构的影响,对40Fe2O3-60P2O5玻璃样品在600～800℃进行热处理,获得了结晶样品.利用XRD、Raman等研究了玻璃结晶化过程中的结构变化,指认了铁磷酸盐玻璃微结构的振动模式的归属.结果表明,在600℃,铁磷酸盐玻璃析出的结晶相主要为:Fe(PO3)3和Fe4(P2O7)3,在700℃、800℃玻璃析出的结晶相主要为Fe4(P2O7)3.利用SEM观察了玻璃样品的微观形貌,结晶相的微观形貌为片状,保温时间延长,片层厚度增加.     

氧化钠对铁磷酸盐玻璃微结构影响的振动光谱分析

为探究铁磷酸盐玻璃对含钠核废物的包容特性,了解Na2O对其微结构的影响.采用熔融-冷却法制备xNaO-(100-x)(40Fe2O3-60P2O5)(0≤x≤50mol％)系列玻璃样品.利用XRD、Raman和FT-IR等手段对玻璃微观网络结构进行表征,对振动光谱的谱带归属进行了指认.结果表明:所有样品均为均质玻璃,铁磷酸盐基础玻璃结构以Q1结构单元为主,伴随Na2O含量的增加,Q1结构单元逐渐减少,Q0结构单元数量逐渐增加,同时形成了P-O-Na+离子键.在Na2O含量40mol％时,Q1结构单元特征谱峰消失.Na2O的引入,引起磷酸盐网络中非桥氧键增加桥氧键减少,导致磷酸盐玻璃结构解聚,微观网络结构松弛.     

Role of Iron in Calcium Phosphate Glasses

Some physical properties okf phosphate glasses con-taining up to about 26 mol% Fe₂O₂ were studied. Pronounced changes in properties were observed at compositions containingabout 6, 10, and 13 mol% Fe₂O₃. The X-ray diffraction spectra of devitrified (heat-treated) samples showed new compounds near these compositions. Electron spin resonance and optical studies confirmed the presence of Fe³⁺ and Fe²⁺ in both 4- and 6-coordination. An increase in total iron in these samples was associated with a decrease in the ratios Fe²⁺ 4-coordinated/Fe³⁺ 6-coordinated 6-coordinated and Fe³⁺ 4-coordinated/Fe³⁺ 6-coordinated up to about 2.0 mol% Fe₂O₃, as shown by the intensity of the optical absorption bands at about 2.0 and 1.0 μm and by the intensity of the ESR lines at g⋍4.2 and 2.0, respectively. Samples containing up to 4.3 mol% Fe₂O₃ showed an increase in Fe³⁺ concentration and a decrease in Fe²⁺ concentration after gamma irradiation. The electrical conductivity and activation energy decreased sharply with increasing Fe₂O₃ content.     

Preparation and Properties of Nitrogen-Doped Phosphate Glasses

Techniques for preparation and the properties of phosphorus oxynitride glasses produced from sodium metaphosphate and nitride compounds are reported. Properties reported include nitrogen content, dissolution rate in water, thermal expansion coefficient, softening point, glass transformation temperature, density, refractive index, microhardness, and infrared absorption.     

Electret Properties of Radiation-Charged Phosphate Glasses

The process of formation of a surface charge in phosphate glasses depending on polarization conditions is investigated. A relationship is established between the chemical composition of glass and its capacity for forming internal electric fields under radiation for glasses of type 0.50P₂O₅ – 0.45RO – 0.05R₂O₃.     

Crystallization Behavior of Potassium Niobium Silicate Glasses

Crystallization behavior of potassium niobium silicate (KNS) glasses having compositions expressed by the general formula x K₂O· x Nb₂O₅·(1 - 2 x )SiO₂, with x = 0.167, 0.182, 0.200, 0.220, and 0.250, has been studied by DTA, X-ray diffraction, second harmonic optical generation (SHG), and electron microscopy. Bulk crystallization of potassium niobates in glasses with compositions near K₂O·Nb₂O₅·2SiO₂, as well as surface crystallization of KNbSi₂O₇ phase, has been established. Transparent glass-ceramics, based on potassium niobates with remarkable SHG signal values, can be obtained from glasses with the lowest silica content, by heat treatment at temperatures just above T _g, while at higher temperatures from all of the glasses under investigation the main crystallizing phase is KNbSi₂O₇ ferroelectric. Applying a dc electric field, grain-oriented crystallization is produced in KNS glasses with development of significantly anisotropic arrangements of KNbSi₂O₇ crystallites.     

Magnetic Behavior and Microstructure of Vanadium Phosphate Glasses

The magnetic properties and microstructures of the vanadium phosphate glass system over the composition range 60 to 90 mol% V₂O₅ were investigated to study magnetic ordering in the glass and the effect of microstructure on its magnetic properties. Direct antiferromagnetic coupling between V⁴⁺ ions in the glassy matrix exists, and a transition temperature near - 70°C was observed. As-cast glasses with high V₂O₅ concentrations separated into two glassy phases; this separation increased the ESR line width as a result of inhomogeneity broadening. The separation, which concentrated the vanadium ions in a vanadium-rich phase, caused a hysteresis in the plot of ESR line intensity vs temperature at the transition temperature. Reduction of the vanadium ions by dextrose added to the melt enhanced phase separation and resulted in weak antiferromagnetic transitions at +70° and -120°C, the Neel temperatures of VO₂ and V₂O₃, respectively.     

Constitution of Sodium, Potassium, and Lithium Phosphate Glasses

The chain-length distributions in solutions of sodium phosphate glasses were reinvestigated using improved paper chromatographic techniques. The range of compositions was extended to glasses of higher Na/P ratios by using a through-flame technique for their preparation. The distributions obtained confirmed the earlier work with the exception that cyclic phosphates were found in solutions of glasses having or approaching the metaphosphate composition despite prolonged heating of the glasses in the molten condition. The earlier observation was that prolonged heating eliminated the cyclic phosphates. As before, no orthophosphate was found, as predicted by Van Wazer, and neither the Poisson nor the "random reorganization" distributions fitted the data for both high- and low-average chain lengths. Although some sort of rearrangement is occurring in the melt, it may not be a completely random process; a rapid change of chemical properties with chain length of the short polymers may have to be taken into account. This was confirmed by similar studies of potassium and lithium phosphate glasses, whose distributions were found to be different enough to demonstrate a cation effect. Consequently, more than stoichiometry is involved.     

Crystallization Behavior of Novel Silicon Boron Oxycarbide Glasses

Homogeneous silicon boron oxycarbide (Si-B-O-C) glasses based on SiO _x C_{4– x} and BO _y C_{3– y} mixed environments were obtained by pyrolysis under inert atmosphere of sol–gel-derived precursors. Their high-temperature structural evolution from 1000° to 1500°C was followed using XRD, ²⁹Si and ¹¹B MAS NMR, and chemical analysis and compared with the behavior of the parent boron-free Si-O-C glasses. The XRD study revealed that, for the Si-O-C and the Si-B-O-C systems, high-temperature annealing led to the crystallization of nanosized β-SiC into an amorphous SiO₂-based matrix. NMR analysis suggested that the β-SiC crystallization occurred with a consumption of the mixed silicon and boron oxycarbide units. Finally, by comparing the behavior of the Si-O-C and Si-B-O-C glasses, it was shown that the presence of boron increased the crystallization kinetics of β-SiC.     

部分稀土掺杂磷酸盐玻璃发光性质分析

磷酸盐玻璃中单掺杂镱（Yb）、铒（Er）、钕（Nd）等稀土元素,对其光谱特性,荧光寿命,低温特性等将产生重要影响。也会改善杂质对磷酸盐玻离性能的影响。     

Dielectric Behavior of Lead-Silicate Glasses Containing Iron

The ac conductivity of lead-silicate glasses containing Fe was measured in the range 4.5° to 500° K to investigate the electronic hopping mechanism in these amorphous materials. Classes containing 0.0, 2.0, and 10.0 wt% Fe₂O₂ were prepared under normal atmospheric conditions. The ac conductivity, which increased with increasing Fe concentration, followed an Arrhenius expression at the higher temperatures. The activation energy for ac conduction increased with increasing Fe concentration, in contrast to the usual decrease in activation energy observed by other workers. The frequency of the conductivity σ (ω) was approximately of the form σ (ω)αω^-n where the exponent increases with increasing Fe concentration and temperature. This behavior is explained by assuming that a distribution of hopping distances and activation energies is involved in the ac electron transport mechanism. At low temperatures, the curves for tanδ vs T for all samples showed a broad relaxation peak at ∼ 70°K. Although this peak is frequency-dependent, it was independent of Fe concentration. The results did not indicate electron hopping between localized states in the temperature range studied.     

Effect of Nucleating Agents on the Crystallization of Calcium Phosphate Glasses

Phase evolution in calcium phosphate-based glass ceramics has been examined. Pure CaO:P₂O₅ readily formed a glass which surface nucleated upon annealing, but volume nucleation at 680°C was observed only after the addition of the nucleating agents, TiO₂ and A1₂O₃. Phase separation of Ti and Al occurred along with the nucleation and growth of a calcium phosphate phase, similar to β-Ca₂P₂O₇. Heat treatments at higher temperatures and/or for longer times resulted in crystallization of A1- and Ti-rich, phase-separated regions. A glass with a higher CaO:P₂O₅ ratio (approximately 2:1) could be prepared only when a total of 25-35 mol% of TiO₂, A1₂O₃, and SiO₂ were present in the batch. The glass phase-separated into respective SiO₂- and CaO/P₂O₅-rich regions on cooling. The SiO₂-rich regions did not influence crystallization and remained amorphous throughout the heat treatments. In the CaO/P₂O₅-rich regions, homogeneous volume nucleation of a Ti-rich phase readily occurred followed by the heterogeneous nucleation and growth on these nuclei of a calcium phosphate phase. Although this phase was macroscopically composed of spherulites, TEM revealed that they consisted of intertwined nanodendrites whose individual arms were approximately 20 nm wide and 50 nm long.     

Nitridation Effect on Properties of Stannous-Lead Phosphate Glasses

Stannous-lead phosphorus oxynitride (Sn-Pb-P-O-N) glasses were prepared by remelting under an anhydrous ammonia atmosphere. Glasses that contained up to ∼4.2 wt% (9 at.%) of nitrogen were obtained. The rate of nitrogen dissolution was studied as a function of remelting time (3–66 h) and temperature (400°–600°C). The onset nitridation temperature was extrapolated to be 315°C; higher nitridation temperatures accelerated nitrogen dissolution. Nitridation of the stannous-lead oxyphosphate (Sn-Pb-P-O) glasses decreased the dissolution rate in water and the thermal expansion coefficient; however, it increased the dilatometric softening temperature, the glass-transition temperature, the microhardness, and the density. The chemical durability of the nitrided glasses increased more than four orders of magnitude with 3.0 wt% of nitrogen content. An increase in the lead oxide content in the stannous phosphate glasses also improved the chemical durability. Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy suggested that nitrogen replaces the terminating hydroxyl ion and the bridging and nonbridging oxygen atoms in the PO4 tetrahedra to form the functional groups –NH<, –N<, and –N=, which leads to enhanced crosslinking of the glass network. Quantitative results regarding these bondings have been given.     

Structure and Electrical Properties of Iron Borosilicate Glasses

Glassesofnominal composition 25SiO₂- 30Na₂O-2Al₂O₃-x Fe₂O₃-(43- x)B₂O₃ (x = 1 to 6 mol%) were prepared by the ordinary melt quenching technique. The influence of Fe₂O₃ substitution at the expense of B₂O₃ on structure and electrical conductivity of sodium borosilicate glasses was investigated. The conductivity was found to increase with increasing Fe₂O₃ content. A double channel conduction mechanism was introduced to explain the electrical conductivity measurements. Moreover, the activation energy decreases considerably in the temperature range from 473 to 773 °K. The activation energies of conduction in various temperature regions were calculated. The conduction was best described by sodium ion migration and hopping between the two valence states of iron. FTIR absorption spectra in the spectral range 1600-400 cm^?1 were measured and a deconvolution analysis technique (DAT) using Gaussian peaks was introduced to analyze the studied glasses. Different characteristic bands were observed and attributed to different types of borate besides silicate vibrational groups.     

Crystallization and Nonlinear Optical Properties of Potassium Niobium Silicate Glasses

The crystallization of the xK₂O · xNb₂O₅· (1 – 2x)SiO₂(x= 0.167–0.250) glasses and glasses close in composition to K₂O · Nb₂O₅· 4SiO₂at the ratio K₂O : Nb₂O₅ 1 is investigated. In high-silica glasses, the metastable phase separation followed by the bulk multiphase crystallization are observed at temperatures close to the glass transition point T _g. The nanostructured transparent glasses that exhibit the optical second harmonic generation (SHG) effect are formed at the early stages of phase separation. The surface crystallization of glasses with the precipitation of the KNbSi₂O₇noncentrosymmetric phase occurs at higher temperatures.     

Elucidating the Effect of Iron Speciation (Fe2+/Fe3+) on Crystallization Kinetics of Sodium Aluminosilicate Glasses

We report on the influence of Fe₂O₃ on the crystallization kinetics of nepheline (Na₂O·Al₂O₃·2SiO₂)‐based sodium aluminosilicate glasses. A series of glasses with varying Al₂O₃/Fe₂O₃ content were synthesized in the system 25Na₂O–(25–x) Al₂O₃–xFe₂O₃–50SiO₂ (x varies between 0 and 5 mol%) through melt‐quench technique. A systematic set of experiments were performed to elucidate the influence of iron speciation (Fe²⁺/Fe³⁺) on the crystallization kinetics of these glasses including: (1) obtaining the details of nonisothermal crystallization kinetics by differential scanning calorimetry, (2) determining the influence of heat treatment on the structure and iron coordination in glasses by X‐ray photoelectron spectroscopy and wet chemistry, and (3) following the crystalline phase evolution in glasses in air and inert environments by X‐ray diffraction and scanning electron microscopy. The crystallization of two polymorphs of NaAlSiO₄—carnegieite (orthorhombic) and nepheline (hexagonal)—was observed in all the glasses, wherein the incorporation of iron promotes the formation of nepheline over carnegieite while shifting the crystallization mechanism from surface to volume. The influence of environment (air versus inert) and iron content on the crystallization kinetics of these glasses is contextualized from the perspective of the devitrification problem usually observed in sodium‐ and alumina‐rich high level nuclear waste glasses.     

Effect of CuO-addition on the Dielectric Parameters of Sodium Zinc Phosphate Glasses

The dielectric properties of sodium zinc phosphate glasses doped with copper oxide have been investigated over a frequency range of 1.05–100 kHz in a vacuum medium (10^?5 torr). Some dielectric parameters, such as dielectric constant ε′, dielectric loss ε′′, dielectric loss tangent (tan δ) and AC conductivity, have been estimated. It is observed that the dielectric constant is strongly dependent on the CuO concentration in the investigated phosphate glasses. The AC conductivity measurements show that these phosphate glasses are good electronic conductors. With the aid of transmission spectra of these glasses, the absorption coefficient and the optical direct bandgap are estimated. The optical bandgap is found to decrease with increasing CuO content indicating the formation of non-bridging oxygens.     

Radiation,Crystallization, and Physical Properties of Cadmium Borate Glasses

Silicon - The melt-quenching method has been used to fabricate Na2B4O7 - CdO glass system. The XRD diffractometer procedure was used to check the status of these samples. Inter-ionic distance (Ri)...     

Optical,Spectral, and Radiation-Shielding Properties of High-Lead Phosphate Glasses

The spectral, optical, physicochemical, radiative, and radiation-shielding properties of glasses in the PbO-P₂O₅-R _m O _n system (where R _m O _n stands for Group I–V element oxides) are investigated as a function of their composition. The composition of a colorless radiation-resistant high-lead glass suitable for production on a semicommercial scale is determined. The properties and optical quality parameters of the glass are studied. The new phosphate glass is a lead metaphosphate containing aluminum, alkali, and alkaline-earth oxides. This glass is resistant to radiation at doses up to 10⁷ R and has an optical transmission edge at 360 nm. The coefficient of absorption of gamma radiation for the new glass is larger than those of dense silicate flints. According to the optical parameters, the new glass lies between dense flints and dense barium flints in the Abbe diagram and compensates for the absence of the latter flints in catalogues of radiation-resistant glasses.     

Bismuth Phosphate Glasses

Homogeneous glasses are formed in the Bi₂O₃-P₂O₅ system up to 35 mol% (63.8 wt%) Bi₂O₃. In property vs composition plots, the thermal expansion coefficient and tan δ exhibit minima, and hardness and activation energy for conduction show maxima at about 20 mol% Bi₂O₃. The deformation temperature of the glasses also increases abruptly at this composition. This anomalous behavior is interpreted in terms of a change in the function of Bi³⁺ ions from network formers to network modifiers.