Ag-Cu双金属纳米颗粒在硅酸盐玻璃中的形成过程

利用两步离子交换结合H2气氛热处理的方法,制备出Ag-Cu双金属纳米颗粒/硅酸盐玻璃复合材料.结合吸收光谱和X射线光电子能谱研究了不同工艺条件下Ag、Cu在玻璃中的深度分布、价态变化及其玻璃网络结构的变化.结果表明:掺杂后的玻璃中银和铜的含量随深度不同有所不同.Ag+-Na+离子交换过程中,Ag+与非桥氧结合形成Si-O-Ag键,样品中的银主要以离子状态存在.H2气氛中热处理后,大部分与非桥氧相连的Ag+被还原,H+随即取代Ag+位置,与非桥氧形成-OH结构,还原出来的Ag0经成核和生长形成银纳米颗粒.第二次Cu+-Na+离子交换后,Cu+被引入硅酸盐玻璃,并有二价铜离子存在,再经过H2热处理后,铜离子被还原,在表层聚集生成铜纳米颗粒.     

离子交换法在钠钙硅酸盐玻璃中原位合成银纳米颗粒的研究

采用离子交换结合热处理法,在商用钠钙硅酸盐平板玻璃中原位形成2～7nm的银纳米颗粒。利用电子探针、X射线吸收近边结构谱、透射电子显微镜和高分辨透射电子显微镜研究了银离子在玻璃中的扩散、还原和生长机理。结果表明：玻璃中同时存在2价和3价铁离子,2价铁离子的存在有利于银离子被还原成中性银原子。银原子在玻璃中成核并生长成纳米颗粒。银纳米颗粒可以在离子交换时形成。提高热处理温度比延长热处理时间更有利于颗粒长大。特别当热处理温度高于玻璃转变温度时,出现Ostwald生长,导致银颗粒迅速长大,密度降低。大部分银纳米颗粒为十四面体单晶,少量为孪晶结构。     

热处理条件对硅酸盐玻璃中原位形成银纳米颗粒的影响

用离子交换结合热处理法制备银(Ag)纳米颗粒-玻璃复合材料.用透射电镜、高分辨透射电子显微镜、Ruthefford背散射谱和紫外-可见光吸收光谱研究了热处理条件对玻璃中原位形成Ag纳米颗粒的影响.结果显示:随着热处理温度升高,玻璃表面的Ag原子逐渐向玻璃内部扩散,其表面摩尔浓度逐渐降低.提高热处理温度和延长热处理时间都有利于提高玻璃中Ag纳米颗粒的体积分数.空气中,高温热处理高掺Ag量的白玻璃样品时发生二次成核,因此,Ag纳米颗粒尺寸呈双峰分布.Ag纳米颗粒尺寸的双峰分布导致其等离子体共振吸收峰出现双峰.在氢气气氛中,在250℃热处理2min,即可在玻璃中形成大量Ag纳米颗粒,颗粒尺寸小于空气中高温热处理样品的尺寸,从而引起表面等离子体共振吸收峰发生蓝移.     

硅酸盐玻璃中银铜双金属纳米颗粒的精细结构

采用离子交换结合热处理方法制备了银铜纳米颗粒／硅酸盐玻璃复合材料。利用扩展X射线吸收精细结构谱和紫外-可见吸收光谱对复合材料中银铜纳米晶的精细结构进行了表征和分析。结果表明：玻璃中银铜纳米颗粒各自分散在玻璃基质中;银纳米颗粒的Ag-Ag键长由于制备过程中产生的张应力使标准银箔发生了膨胀;铜纳米颗粒表面的Cu-O配位数由于Cu-Cu配位的出现而降低,且Cu-Cu配位数远小于标准铜箔中Cu-Cu的配位数,其键长也发生了收缩。     

玻璃中卤化银纳米棒定向排布制备

围绕含AgCl钠硼硅酸盐玻璃的熔融制备、析晶热处理、高温拉伸及高压还原工艺，对于玻璃中卤化银纳米棒的形成、定向排布以及对于偏光性能的影响规律进行了研究，发现卤化银晶粒更易于在富钠硼相中析出，较佳的热处理制度是析晶温度615℃、保温时间12 h。玻璃中卤化银纳米棒的形成及定向是玻璃拉伸温度、拉伸应力与拉伸速度三者的有机结合。在拉伸温度570℃、拉力735 N、拉伸速度120 mm/min条件下，玻璃样品中Ag Cl纳米棒的平均直径98 nm、平均长度558 nm、纳米棒的平均长径比1.0:5.6，并沿玻璃拉伸方向定向排布。通过高压还原后玻璃的偏光性能研究，拉伸后玻璃表层单位面积内AgCl纳米棒的数量越多，还原处理后玻璃的消光比越高。     

铜纳米颗粒在硅酸盐玻璃中的形成及其局部结构

用离子交换结合H2气氛热处理的方法制备出铜纳米颗粒/硅酸盐玻璃复合材料.利用光学吸收谱和X射线吸收精细结构谱分析了铜纳米颗粒在玻璃中的形成机理及其局部结构.结果表明:提高H2气氛处理温度有利于提高Cu纳米颗粒在玻璃中的体积分数,在其它工艺条件相同的情况下,离子交换时间从0.5 h延长到1.0 h对cu纳米颗粒在玻璃中的体积分数影响不大.Cu在离子交换硅酸盐玻璃中仅存在Cu-O配位结构,热处理后铜原子在玻璃中存在2种局域结构环境:一是处于铜氧化物的配位环境:另一是处于金属铜的配位环境.玻璃中铜离子以-价存在,其周围存在2个氧配位,Cu-O键长在0.185～0.186 nm之间.随着Cu颗粒尺寸的降低和Cu小分子团簇质量分数的增加,Cu-Cu配位的无序度增大.含小分子铜团簇多的样品,Cu-Cu最近邻原子间距离与铜体材料中的Cu-Cu最近邻原子间距离(0.255 nm)相比发生收缩;含铜纳米颗粒较多的样品,Cu-Cu最近邻原子间距离与铜体材料中的Cu-Cu最近邻原子间距离相比发生膨胀.     

银纳米颗粒/玻璃复合材料的吸收光谱特征

利用离子交换结合热处理方法,制备出Ag纳米颗粒掺杂硅酸盐玻璃复合材料。通过改进的Mie理论拟合了不同制备条件下Ag纳米颗粒的吸收光谱,得到了它们的尺寸和体积分数。拟合结果表明:在热处理条件相同时,离子交换时间越长,样品中Ag纳米颗粒的尺寸越大,体积分数越高;在离子交换条件相同时,随着后续热处理时间的延长或温度升高,样品中Ag纳米颗粒的尺寸变大,体积分数提高。相比于空气热处理,氢气热处理可以显著降低样品中Ag纳米颗粒的形成温度和时间。氢气气氛下形成的Ag纳米颗粒小于空气气氛下形成的Ag纳米颗粒,导致其等离子体共振吸收峰相对空气中热处理的样品发生蓝移。     

稀土离子掺杂碲酸盐发光薄膜的制备及其荧光增强

利用直流电场辅助固态膜离子交换技术,将金属银引入硅酸盐玻璃基片中,制备了表层含银纳米颗粒的改性硅酸盐玻璃基片。以1,2-丙二醇碲和硝酸锌、硝酸铒、硝酸镱为原料,通过非水解溶胶-凝胶法制备稀土离子掺杂的碲酸盐发光薄膜材料。利用X射线衍射、透射电镜、差热分析、场发射扫描电镜、原子力显微镜、荧光光谱仪、立体显微镜等测试手段,研究了玻璃基片中的银纳米颗粒及其形貌、薄膜的物相、形貌、发光性能及改性基片的荧光增强效应。结果表明:改性硅酸盐玻璃基片表层含有粒径为10～20nm的银纳米颗粒;制备的Er~(3+)-Yb~(3+)掺杂的碲酸盐发光薄膜为无定形态,薄膜的微观形貌良好,厚度约200nm;在改性玻璃基片上制备的薄膜在980nm激光泵浦下,可在410,527,547,660nm和1540nm附近发射荧光,其发光强度显著提高,最大可提高180倍。     

GO/Ag纳米复合颗粒的制备及其抗菌性能的研究

采用了改进的Hummers法制备氧化石墨烯(GO),并使用绿色环保的还原剂葡萄糖还原银氨溶液中的银氨离子,在没有分散剂的情况下,制备了氧化石墨烯/银纳米复合颗粒(GO/Ag)材料。各项材料学表征表明,制备的GO/Ag纳米复合颗粒中的银纳米粒子在GO片层中分布均匀,没有出现团聚的现象,粒径几乎均一,为40 nm左右。在以金黄色葡萄球菌为模型的抗菌实验中发现,GO/Ag纳米复合颗粒具有很强的杀菌效果,且对金黄色葡萄球菌的抑制性要明显强于GO。     

无铅金红玻璃的研究

以钠钙硅酸盐代替铅硅酸盐为基础成分,掺杂金制备了金红玻璃。用分光光度计测量了的透过率曲线。用扫描电镜观察了玻璃表面形貌及金颗粒尺小。结果表明:玻璃的吸收峯为540nm,金颗粒尺寸为40~80 nm,玻璃呈玫瑰红色。这种无铅玻璃减少铅的污桨,降低了成本。     

IR Practical Extinction Coefficients of Water in Alkali Lime Silicate Glasses Determined by Nuclear Reaction Analysis

Infrared spectroscopy (IR) is widely used to determine the water concentration in glasses, whereas determination of the IR practical extinction coefficient is necessary to deduce the absolute water concentration of glasses on the basis of Beer–Lambert law. From the nuclear reaction analysis data, the IR practical extinction coefficients of water were successfully determined for the alkali lime silicate glasses with different levels of sodium/potassium cation (Na/K) ratio. The two‐band method is well‐known to be useful for the determination of the water concentration in some alkali lime silicate glasses. It is proved here that the two‐band method is not applicable to the variety of composition for alkali lime silicate and soda lime aluminosilicate glasses, whereas it is valid for the similar composition of soda lime silicate glasses [SLS: Composition (in mol%) 16Na₂O·10CaO·74SiO₂]. The single‐band procedure with the IR practical extinction coefficient is crucial for the determination of the precise water concentration in the wide variety of glass composition although the determination of the IR practical extinction coefficient is troublesome. It also appears that the ion radius of alkali affects the IR practical extinction coefficient and the chemical state of OH group in glasses.     

Mechanochemical Wear of Soda Lime Silica Glass in Humid Environments

The mechanochemical wear of multicomponent glasses was studied under controlled humidity conditions using a reciprocating ball‐on‐flat tribometer. For dry conditions, the surfaces were extensively damaged by scratching for all of the glasses, while for humid conditions the wear behavior varied with the glass composition suggesting a chemical effect on scratch behaviors of glass surfaces. The wear of soda lime silica (also called sodium calcium silicate) glass was suppressed with increasing humidity, while the borosilicate and barium boroaluminosilicate glasses showed an increase in wear volume with increasing humidity. The unique humidity dependence of the observed mechanochemical wear of soda lime silica glass supports the hypothesis that hydronium ion formation in the sodium‐leached sites of the soda lime glass enhances its wear resistance.     

Characterization of Invert Soda Lime Silica Glasses Containing High Titania Content Together with their Glass Ceramics

Silicon - Collective structural, optical and thermal properties were investigated for some prepared soda lime silicate glasses containing high TiO2 contents (35, 40, 45%). X-ray diffraction and...     

In Vitro Bioactivity Behavior of some Borate Glasses and their Glass-Ceramic Derivatives Containing Zn2+, Ag+ or Cu2+ by Immersion in Phosphate Solution and their Anti-Microbial Activity

Silicon - Some soda lime borate glasses containing sele- cted Zn2+, Ag+ or Cu2+ ions or all of them were prepared together with their glass ceramic derivatives by thermal heat-treatment two step...     

Enhancement of mechanical properties and chemical durability of Soda-lime silicate glasses treated by DC gas discharges

We report for the first time a study on non-contact thermal poling of soda lime silicate glasses using DC gas discharge. In this work, the formation of a glow discharge is evidenced during the thermal poling treatment (longer than 30 minutes). The hardness and the chemical durability of glasses poled under different conditions (contact or non-contact) and atmospheres (nitrogen or air) are measured and compared to that of un-poled reference glass. The results reveal enhanced mechanical and chemical properties for samples poled under nitrogen as compare to air poled or soda lime silicate glass samples. A structural and chemical analysis of surface of the glass using IR-reflectance measurement and ToF-SIMS is also presented. The formation of a “silica-like” layer on the surface of nitrogen poled glasses is observed, which is likely associated with the enhancement of surface properties. On the other hand, the introduction of protons beneath the surface of glasses poled under air leads to the formation of a hydrated alkaline earth silica layer. Based on the observations a mechanism behind the sustainability of the plasma under DC conditions is proposed.     

化学强化玻璃的发展现状及研究展望

化学强化玻璃因其表面压应力层使玻璃的机械强度提高,被广泛用于电子产品显示屏领域。本文对钠钙玻璃、铝硅玻璃、磷铝硅玻璃、锂铝硅玻璃等的化学强化进行了综述,对进一步通过优化骨干网络结构来提高玻璃本征强度获得更高机械强度的玻璃做出了可行性探索。总结了目前化学强化玻璃面临的问题及发展方向,为相关科学研究和工业生产提供参考。     

Electric field-assisted ion exchange strengthening of borosilicate and soda lime silicate glass

In this study, we investigate the effects of electric field-assisted ion exchange (EF-IE) on potassium for sodium ion exchanges of soda borosilicate and soda lime silicate glasses. The results show that applying an electric field (E-field) with the intensity of 1000 V cm⁻¹ for few minutes produces an exchanged layer with a thickness comparable to the conventional chemical strengthening for 4 hours. There is a critical E-field that increases the mobility and, therefore, the diffusion coefficient of the potassium ions in the glasses. The increase is, perhaps, related to the evolution of the glass structure due to the penetration of potassium ions under an E-field. Vickers indentations showed that strong compression is generated in the glass by EF-IE; however, the bending strength improvement is limited because of the presence of large surface defects and the stress distribution inhomogeneity.     

Electronically Conductive Vanadate Glasses for Resistive Plate Chamber Particle Detectors

Particle detectors are constantly being built and refitted with new technology to improve the spatial resolution, radiation hardness, and speed at which the detector can capture particle events. One of the most crucial components of a modern collider experiment is the hadron calorimeter. One of the proposed improvements on future hadron calorimeters is to utilize resistive plate chambers (RPCs). They provide the spatial and energy resolution as well as could provide speed and radiation hardness. RPCs depend on manufacturing electrically conductive glasses that are mechanically strong, durable, radiation resistant, and not ionically conductive. To achieve such requirements, vanadate glasses were developed as alternatives to current prototypes which use soda lime silicate glasses. The conductivity, oxidation states of vanadium, radiation hardness, as well as the prototype performance, were tested on vanadate glasses. The prototype tests show that using 0.40ZnO−0.40TeO₂−0.20V₂O₅ can improve the RPC detector rate up to 100 times.     

Dissolution Rates of Silicate Glasses in Water at pH 7

Dissolution rates of different glasses in buffered solutions of constant pH of 7 were measured by weight change, profilometry, and ion implantation with Rutherford backscattering. Rates with different techniques agreed within experimental error. Natural obsidian glass dissolved most slowly, at a rate comparable with those of quartz and crystalline aluminosilicate minerals. Commercial soda–lime glass containing alumina dissolved slowly, at about the same rate as vitreous silica; soda–lime silicate glasses both commercial and laboratory without alumina dissolved much more rapidly. Pyrex borosilicate glass dissolved at a rate intermediate between those of soda–lime silicate glasses with and without alumina; at room temperature Pyrex borosilicate glass dissolved about 100 times faster than a commercial soda–lime glass containing alumina. We suggest that surface structure is the main factor determining the relative dissolution rates of silicate glasses. Glasses with transformed surface layers caused by hydration dissolve most rapidly; phase separation and openness of the glass structure are also important factors.