New Photoluminescence Phenomena of Ge/SiO_2 Glass Synthesized by Sol-gel Method

New Ge/SiO_2 glasses have been synthesized by heating the GeO_2/SiO_2 dry gels under H_2gas at 700℃. The resulting fluorescence spectra show that this kind of Ge/SiO_2 glasses emit strongphotoluminescence at 392 nm (3.12 eV), medium strong photoluminescence at 600 nm (2.05 eV)and weak photoluminescence at 770 nm (1.60 eV) respectively. Possible photoluminescencemechanisms are also discussed based on the results of X-ray diffraction (XRD) and X-rayphotoelectron spectra(XPS).

Synthesis and spectral properties of Nd-doped glass-ceramics in SiO_2-CaO-MgO system prepared by sol-gel method

SiO2-CaO-MgO glass and glass-ceramic powder doped with Nd3＋ were synthesized with sol-gel method. Tetraethylorthosilicate （TEOS）, Ca（NO3）2？4H2O, Mg（NO3）2？6H2O, Nd（NO3）3？6H2O, ethanol, distilled water, and HNO3 were used as starting materials. The synthesized powder’s properties were examined with simultaneous thermal analysis （STA）, X-ray diffraction （XRD）, photoluminescence （PL） and scanning electron microscopy （SEM） analysis. The STA curves showed that the softening point and crystallization temperatures were shifted to higher temperatures with increasing dopant content. Regarding XRD patterns of glass samples, Nd was found to act as an intermediate oxide in glass matrix. The XRD patterns of glass-ceramic samples indicated that bredigite and akermanite crystallized in the glass matrix after heat treating at 900 oC. The fluorescence spectra showed that glass-ceramics emitted much stronger irradiation than glasses with the same dopant content. The SEM images illustrated uniform and homogeneous distribution of applied oxides in glass and glass-ceramic compositions.

Synthesis of RE-Ag,Al-RE-doped sol-gel glass and films for solar cells

The paper dealt with the study of fluorescence properties of sol-gel systems doped with rate-earth ions and co-doped with silver. The general problem for these types of inorganic phosphors was a very low absorbance in the visible range. Therefore, a sensitizer of luminescence of the rare-earth ions should be selected and used. The sensitizer should possess a good absorbance in the visible range and strong interaction with the rare-earth ions. In this study silver ions were selected as the sensitizer.

Interfacial characteristics and dynamic mechanical properties of W_f/Zr-based metallic glass matrix composites

Tungsten fiber reinforced Zr41.25Ti13.75Cu12.5Ni10Be22.5 metallic glass matrix composites were fabricated by means of melt infiltration casting.Their dynamic compressive tests were performed using a Hopkinson bar.The relationship between the interfacial characteristics and the dynamic compressive behavior was investigated.The results indicate that the interface characteristics of composites include interfacial diffusion and interfacial reaction,and the interfacial shear strength increases when the interfacial reaction is serious.The dynamic plastic performance are improved obviously if the suitable interface reaction occurs.The failure occurs by shear and the fibers split longitudinally if there is no interface reaction or a little reaction;in contrast,holistic failure occurs if there is too much interface reaction.

Synthesis and Photocatalytic Activity of Fe-doped TiO_2 Supported on Hollow Glass Microbeads

In this paper, Fe-doped TiO_2 photocatalyst supported on hollow glass microbeads(Fe-TiO_2 /beads)is prepared by dip-coating method, which uses hollow glass microbeads as the carriers and tetrabutylorthotitanate [Ti(OC_4H_9)_4] as the raw material. The phase structure, ingredient, morphologies, particle size and shell thickness of the products are characterized by X-ray powder diffraction(XRD), energy-dispersive spectroscopy(EDS) and field emission scanning electron microscope(FESEM). The feasibility of photocatylic degradation of Rhodamine B(Rh B) under illumination of UV-vis light is studied. The results show that the core-shell structure catalyst is composed of Fe-doped anatase TiO_2 and hollow glass microbeads, and the catalytic activity of the TiO_2 is markedly enhanced by Fe ion doping. The optimum concentration of Fe ion is 0.1%(molecular fraction) in the precursor and the photocatalytic activity can be increased to 98% compared with that of the undoped one. The presence of ferrum elements neither influences the transformation of anatase to rutile, nor creates new crystal phases. The possible mechanism of photocatalytic oxidation is also discussed.

Synthesis and structural characterization of macroporous bioactive glass

Porous sol-gel glass of CaO-SiO2-P2O5 system with macropores larger than 100 μm was prepared by adding stearic acid as pore former when the sintering was carried out at 700 ℃ for 3h.The sol-gel porous glass shows an amorphous structure. The diameter of the pore created by pore former varies from 100 to 300 μm, and macroporous glass has a narrow and small pore size distribution in mesoporous scale. The porosity and pore size of macroporous bioactive glass can be controlled.

Optical properties of CeO_2/Fe_3O_4 solar control glass coating

A cerium-iron oxide solar control coating on glass was prepared by citric acid sol-gel method, dip-coating techniques and proper heat treatment process. Results show that the cerium-iron glass coating is composed of nanocrystalline CeO2, Fe2O3, and nano holes. The cerium-iron glass coating has high transmittance in visible light, low UV and near IR transmittance. The wavelength of absorption edge for most glass coating has an obvious redshift to about 375 nm. There exist a wide absorption band at the range of 800-1600 nm and high transmittance at the wavelength from 400 nm to 800 nm, and the solar energy and visible transmittances are 50% and 65%, respectively. It ascribes to the high content of trivalence cerium and bivalence iron ions in the cerium/iron coating. It is indicated that this kind of glass coating has very good UV-sheering and heat-insulating property, can be used as an effective solar control glass in automobile and architecture.

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.

Mineral formation on dentin induced by nano-bioactive glass

The object of this study was to evaluate the effect of bioactive glass （BG） size on mineral formation on dentin surfaces. Totally demineralized dentin discs were treated using BG suspensions with different particle sizes： i.e., microscale bioactive glass （m-BG）, submicroscale bioactive glass （sm-BG） and nanoscale bioactive glass （n-BG）. Field-emission scanning electron microscopy and 3D profile measurement laser microscopy were used to observe the surface morphology and roughness. It was found that all BG particles could promoted mineral formation on dentin surfaces, while plug-like depositions were observed on the dentin discs treated by n-BG and they were more acid-resistant. The present results may imply that n-BG has potential clinical application for dentin hypersensitivity treatment.

Preparation and structure of BaTiO_3 ferroelectric glass ceramics

The developments of miniaturization and intergration for electronic components areincreasing greatly the demands for multilayer and thick-film capacitors. The thickness of themonolayer in these capacitors is changing below 20μm. It is necessary to make this kind ofcapactiors from raw materials with high homogeneousness at the level of submicrometres.

Growth of PbTiO_3 crystallites in gel glass and their size effect

The special glass ceramics with ferroelectric main-crystalline phase are very usefullbecause of their good electro-optical effect, excellent high dielectric properties and low therm-al expansion coefficient. This kind of materials has been noticed since the 1960s. Withthe development of ferroelectric nanocrystallites and fine composite technology nowadays, itis desired to get ferroelectric nanocrystallites with better-controlled size and to prepare newcomposite systems. Overcoming agglomeration among ferroelectric ultrafine grains is nec-essary. So it is important in this field to get the ultrafine PbTiO3 grains in situ confinedgrown in glass with better controlled size.

真空玻璃真空度在线检测技术与应用

采用光弹法和动态法在线检测真空玻璃的真空度.试验测试表明,通过光弹仪可以观测到真空玻璃支撑物与玻璃支撑点处因应力集中而产生的应力光斑,而且随着真空度的提高,应力光斑直径也增大.同时,采用动态法测得的真空玻璃的固有频率也随着其真空度的增大而增大.对该两种方法的原理、检测过程及工程应用进行了分析,该两种方法特点是操作简单,结果直观可靠,易于实现真空玻璃实际工程在线检测.

玻璃空间电离辐照着色损伤动力学研究

空间电离辐照主要由能量连续变化的粒子组成,绝大多数粒子穿透能力小,因此,空间电离辐照对玻璃的着色损伤必然随深度而呈现一种复杂的变化,针对这一现象,并且考虑到玻璃中色心的弛豫消失,本工作建立了一种适用于玻璃空间电离辐照着色损伤动力学研究的方法.以K9-HL玻璃为研究对象,利用空间电离辐照作用在玻璃中随深度变化的Monte Carlo模拟结果,研究了该玻璃在轨(近地点350 km,远地点425 km,轨道倾角51.6°)电离辐照着色损伤过程,讨论了航天器用玻璃抗辐照性能考核方法,分析了玻璃空间电离辐照着色损伤的深度分布,提出了航天器用玻璃材料抗电离辐照损伤加固的关键点.此外,对不同石英玻璃防电离辐照层保护的K9-HL玻璃在轨光学性能做了研究.

分子动力学法对Cu-Ag合金熔化及凝固过程的模拟

借助镶嵌原子势(EAM)利用等压等温的分子动力学方法(NPT-MD)模拟共晶Cu40Ag60合金的熔化,凝固过程.利用径向分布函数和对分析技术研究Cu40Ag60台金在不同的冷却速率(1×1011,1×1012,5×1012,1×1013。及1×1014 K/s)下的非晶形成能力和微观结构演化.研究发现Cu40Ag60合金形成非晶态需要极大的冷却速率.

水泥-水玻璃双液注浆在饱和动水砂层隧道施工中的应用研究

针对隧道在饱和动水砂层中自稳能力差、施工难度大的现状,通过现场注浆试验对水泥-水玻璃注浆压力、TSS管注浆工艺等进行了研究。研究表明新奥法中应用水泥-水玻璃双液注浆方法加固饱和动水砂层隧道可以取得较好的效果。

基于基团贡献法和分子动力学预测聚间苯二甲酰对苯二胺的玻璃化转变温度

采用基团贡献法(GC)和分子动力学法(MD)模拟了聚间苯二甲酰间苯二胺纤维(MPDI)和聚对苯二甲酰对苯二胺(PPTA)的玻璃化转变温度,并与实验值进行了对比.结果表明,使用基团贡献法和分子动力学法测得的MPDI和PPTA的玻璃化转变温度与实验值接近,说明基团贡献法和分子动力学法可以用来预测芳香族聚酰胺的玻璃化转变温度.在此基础上,采用GC和MD预测了聚间苯二甲酰对苯二胺(PPIA)的玻璃化转变温度.在MD模拟中,对密度、比体积、回转半径和非键相互作用随温度的变化规律进行了分析.结果表明,自由体积理论能较好地解释PPIA的玻璃化转变现象,其中非键相互作用随温度的变化是玻璃化转变的本质原因. PPIA的玻璃化转变温度介于MPDI和PPTA之间,有望成为综合性能介于两者之间的另一种高性能聚酰胺.

风震联合作用下高层建筑主体结构和玻璃幕墙的性能研究

为研究风、地震单独及联合作用下,主体结构和玻璃幕墙的性能变化和相互影响,基于高烈度区98 m高框筒结构,依据规范要求增设玻璃幕墙形成总体有限元分析模型,选取3组三向地震动记录,并通过比例为1∶440的缩尺模型风洞试验获得不同重现期的风压时程数据,采用动力弹塑性分析方法,研究风、地震单独与联合作用下主体结构和玻璃幕墙的受力变化。结果表明:主体结构对玻璃幕墙的受力影响大于玻璃幕墙对主体结构的,在风、地震单独及联合作用下,主体结构的层间变形大于玻璃幕墙自身变形。在设防大震和超烈度大震作用下,主体结构的响应和玻璃幕墙的损毁范围随荷载增大而增大,结构变形增长大于结构基底剪力;玻璃幕墙在风荷载作用下未坏,主体结构完好,结构基底剪力、顶部楼层位移和楼层层间位移角呈线性增长;与单独大震作用相比,在1.1倍100年重现期风压和大震联合作用时,结构出现扭转现象,楼层层间位移角之比由1.0增至1.3,主体结构和玻璃幕墙的非线性响应大于风震单独作用的叠加,其中结构顶点位移和最大层间位移角为单独作用时求和值的121%、106%。在大震及风震联合作用下,玻璃幕墙容易发生破坏的位置为平行地震作用主向的侧面。

Application of Bi-axial Warp Knitted Structures in Concrete Constructions

The warp knitted bi-axial directionally oriented structure (D. O. S. ) reinforcement substrates applied to building construction are discussed in comparison to woven fabrics. One of usage barriers of reinforced cement with gloss-grid is its sensitivity to alkali existed in the cement which will lead to the reduction of its service-life. The tests show that the treatment by sol-gel method to protect the composite from alkali corrosion is effective. Then two formulae of sol-gel solution are also recommended here for application.

硅碱钙石可加工微晶玻璃的析晶动力学研究

采用差热分析的方法,根据不同升温速率下的析晶峰温度研究了可加工微晶玻璃的析晶动力学参数,并采用X-ray衍射对其在不同温度下的晶相组成结果对其析晶过程进行了研究,最后根据衍射曲线,计算了可加工微晶玻璃中的晶体含量约为40%。

玻璃钢定向器热弹耦合动态特性分析

为掌握玻璃钢定向器在火箭弹和燃气流作用下的动态特性情况,采用瞬态有限元法对某玻璃钢定向器进行真实工况下热弹耦合性能的数值仿真与分析,获得了玻璃钢定向器热弹动态特性和火箭弹管内运动与作用情况。结果表明某玻璃钢定向器在开始阶段产生的响应应力和应变较大,定向器后端产生的响应应力和变形位移比前端大;燃气流热载荷对玻璃钢定向器的动态性能产生一定影响,其主要影响是在火箭弹出定向器以后,使定向器产生较大热变形。