Tb掺杂SiO2-B2O3-NaF玻璃的制备及发光性质

使用正硅酸乙酯、硼酸和氟化钠为前驱体,0.10 mol•L-1TbCl3溶液为掺杂剂,通过溶胶-凝胶方法制备了Tb3＋掺杂的SiO2-B2O3-NaF玻璃,研究了Tb3＋在SiO2-B2O3-NaF体系中的发光性质,结果显示发光体能产生强的绿色发光(544 nm),归属于Tb3＋的5D4—7F5电子跃迁.Tb3＋含量不同时,除发光强度不同外,其发射光谱基本相同,并且在低掺杂Tb3＋样品和低退火温度样品中检测到了来自5D3跃迁产生的峰,其跃迁随Tb3＋掺杂浓度的增加和退火温度的升高而发生猝灭,这种现象归因于5D3－5D47F6—7F0和/或5D3—7F07F6—5D4跃迁中发生了交叉弛豫现象.Tb3＋在SiO2-B2O3-NaF玻璃中的激发光谱由一个宽峰和一系列窄峰组成,宽峰最大波长位于230 nm,对应于Tb3＋的4f 8—4f 75d 1跃迁,一系列窄峰位于300～380 nm处,归属于4f 8跃迁,所有发光材料的XRD和TEM测试显示材料是非晶态的.     

Solubility and Partitioning of Minor-actinides and Lanthanides in Alumino-borosilicate Nuclear Glass

We prepared a heterogeneous SiO2-B2O3-Na2O-Al2O3-CaO-La2O3 glass containing 11.76 wt.% AmO2. The composition of this heterogeneous material was determined from that of non-active glasses in which Am was fully substituted by Nd. For trivalent ion concentrations above the solubility limit, crystal formation occurred in the form of apatite-like silicates, this in both active and non-active glasses. Additions of Am⁺³ and Nd³⁺ led to depolymerization of the silicate network which is consistent with the modifier role expected from these cations. Thus, we can compare the incorporation mechanisms of neodymium and americium in the glassy network and within the apatite-like crystalline phases.     

Understanding the solubility and crystallization of molybdenum in high-sodium borosilicate glasses: effect of lanthanum oxide

Journal of Radioanalytical and Nuclear Chemistry - The simplified 8-oxide system (SiO2-B2O3-Na2O-Al2O3-CaO-TiO2-MoO3-La2O3) has been prepared under two types of cooling methods, and analyzed with...     

超临界干燥法制备Fe2O3-SiO2气凝胶

以正硅酸乙酯（TEOS）和硝酸铁为原料,采用溶胶-凝胶法和超临界干燥工艺制备了Fe2O3-SiO2气凝胶,研究了Fe2O3-SiO2醇凝胶的形成条件的影响,并对所得气凝胶样品结构特性进行了初步表征．所得气凝胶样品是由直径约8nm的胶体粒子构成的低密度、高孔隙率的块状非晶固态材料．     

纳米复合材料CoFe2O4/SiO2的制备和表征

采用溶胶-凝胶法制备了(CoFe2O4)x/(SiO2)1-x纳米复合材料. 利用TG/DTA, XRD和Mssbauer效应研究了热处理过程中干凝胶的变化及样品的结构、晶粒尺寸和磁性. 结果表明, 随着SiO2含量的增加, 样品中CoFe2O4的晶粒尺寸和内磁场逐渐变小, 并从磁有序状态转变为超顺磁状态.     

Atomic Force Microscopy Study of NaOH Corroded Al2O3-TiO2-SiO2 Coatings on Glass

Atomic force microscopy (AFM) was used to study the performance of 80 nm thick Al2O3-TiO2-SiO2 sol-gel coatings on glass substrates following corrosion in 1 M NaOH solutions at 60°C. The as-prepared coatings were homogeneous on a nanoscale and displayed the glass pattern before corrosion. Layers with different compositions behaved differently during the corrosion process. Thus, TiO2 or TiO2-dominated layers had tetragonal-like crystals on their surfaces after corrosion, possibly of anatase composition. On the other hand, layers with a molar ratio Al2O3 : SiO2 near 1 : 2 displayed a pseudo-hexagonal morphology, possibly with a nepheline (Na2O · Al2O3 · 2SiO2) composition. Layers of 5Al2O3-40TiO2-55SiO 2 were corroded is a stepwise fashion and had no special surface morphology.     

甲烷氧化偶联:Mn2O3-Na2WO4/SiO2催化剂的金属氧化物MOx(M=Ti,Mg,Ga,Zr)改性及掺杂效应研究

甲烷 (页岩气、天然气、可燃冰和煤层气的主要成分) 是地球上储量巨大的优质能源和高品味的碳氢资源, 我国也拥有储量居全球前列的页岩气、可燃冰和煤层气. 虽然甲烷经由合成气可以间接转化为乙烯等产品, 但工艺流程长以及合成气造气高温、高能耗和高物耗也是不争的事实, 这在一定程度上降低了间接合成路线的竞争优势. 特别是, 甲烷的间接转化需要将本应部分保留于产品的 C-H 键全部打断生成合成气, 然后再在催化剂作用下重组得到烃类产品, 故而并不完美.因此, 甲烷的直接转化一直是科学家孜孜以求的理想路径, 甲烷氧化偶联制乙烯 (OCM 反应) 也再一次引起关注.目前, Mn2O3-Na2WO4/SiO2是最富有应用前景的催化剂, 但其适宜反应温度仍高达 800 ℃ 以上, 极大地制约了其工业化应用. 为提高其低温催化性能, 本文采用金属氧化物 MOx(TiO2, MgO, Ga2O3或 ZrO2) 对 Mn2O3-Na2WO4/SiO2催化剂进行了掺杂改性, 利用扫描电子显微镜、N2吸附-脱附等温曲线、X 射线衍射、拉曼光谱、电感耦合等离子体原子发射光谱等手段对改性后的催化剂进行了系统表征. 结果表明, TiO2掺杂的 Mn2O3-Na2WO4/SiO2催化剂在 700 ℃(催化剂床层温度)下, CH4转化率可达 23%, 同时 C2-C3烃类选择性约为 73%, 且能够稳定运行 300 h 无失活迹象; MnTiO3的形成对提高OCM 反应的低温活性和选择性至关重要, 本质在于低温 (≤ 700 ℃) 化学循环"MnTiO3?Mn2O3"的形成替代了未改性催化剂的高温 (＞ 800 ℃) 化学循环"MnWO4?Mn2O3". 对于 MgO 改性的 Mn2O3-Na2WO4/SiO2催化剂, 其催化性能与未改性催化剂相当, 反应过程中 Mn2O3与 MgO 生成了新物相 Mg2MnO4; 虽然也形成了新的 MnWO4?Mg2MnO4氧化还原循环, 但是该循环与 MnWO4?Mn2O3循环类似, 需在高温下才可高效进行. 对于 Ga2O3或 ZrO2改性的催化剂, 其催化性能低于未改性催化剂, 原因在于反应过程中 Ga2O3或 ZrO2的引入促进了 MnWO4物相的生成并对其有稳定作用, 反应后的催化剂无论是体相还是表面都只能检测到 MnWO4, 推测认为α-方石英、Na2WO4和 Mn2O3的缺失是导致 Ga2O3或 ZrO2改性催化剂性能下降的主要原因.     

微量热法研究载银B2 O3 -SiO2 -Na2 O玻璃对大肠杆菌的抑制作用

采用微量热法研究了载银B20,-SiO：-N％0玻璃对大肠杆菌作用的热功率输出曲线,得到了大肠杆菌在不同的抗菌剂浓度下的生长速率常数k,抑制率I等参数,定量说明了载银B2O3-SiO2-Na2O玻璃对大肠杆菌有很强的抑制作用。     

Sm3+掺杂CaO-SiO2-B2O3发光玻璃的制备、表征及性质

用高温固相法合制备了以CaO-SiO₂-B₂O₃为基质，Sm³⁺为激活离子的发光玻璃。对Sm³⁺的淬灭浓度、基质中的硼硅比例、其他稀土离子的敏化作用以及基质组成等因素对玻璃发光特性的影响进行了探讨，并用红外和X-衍射分析对样品的结构进行了表征。结果表明：当Sm^3＋掺杂的物质的量分数为1.2%,激发波长λ ＝ 404 nm时,玻璃体60CaO-20SiO₂-20B₂O₃∶1.2Sm^3＋的发光强度为4 838 A.U.( λ ＝ 606 nm );这种发光玻璃具有将紫外及近紫外光转换为橙红色光的特点。少量的Eu^3＋的掺入，对玻璃体的发光起敏化作用；玻璃体中的组分CaO可被ZnO替代。     

Eu3+掺杂Y2O3-Al2O3-SiO2玻璃的制备与荧光性能研究

采用高温熔融法制备了Eu³⁺掺杂Y₂O₃-Al₂O₃-SiO₂荧光玻璃,探讨了成分对该体系玻璃形成能力的影响,并对不同Eu³⁺掺杂浓度下的荧光性能进行了研究.结果表明,熔融温度为1500℃条件下,SiO₂含量对该体系的玻璃形成能力影响明显,Y/Al摩尔比为3/5时,SiO₂含量在52%-68%(摩尔分数)范围内时可以获得玻璃.掺杂Eu³⁺的Y₂O₃-Al₂O₃-SiO₂玻璃具有荧光性能,在395nm波长激发下,在588 nm和614 nm处出现明显的发射峰.随着Eu³⁺掺杂浓度的增加,该荧光玻璃的发射波长不变,但发射强度有所变化;当Eu³⁺掺杂浓度为1.5%(摩尔分数)时,特征发射峰强度最大.     

Protonic Conduction in P2O5-SiO2 Glasses Prepared by Sol-Gel Method

Protonic conduction in 10P2O5·90SiO2 and 20P2O5·80SiO2 (mol %) glasses prepared by sol-gel processing was investigated as a function of the content of molecular water adsorbed in the pores. The results show that the electrical conductivity of the glasses containing adsorbed molecular water varies exponentially with the reciprocal absolute temperature and increases with the increase of the content of the adsorbed molecular water. The double-bonded oxygen and the high affinity of phosphorus for oxygen make protons easily to release and transfer, which is favorable to the protonic conductivity.     

作为吸附载体用微孔玻璃珠的研制

研制出Na_2O-B_2O_3－Al_2O_3－SiO_2系统玻璃，粉碎成一定粒度的颗粒，制成2mm左右的玻璃珠，经过热处理分相、酸溶、水洗、烘干，得到了气孔率为24％左右的微孔玻璃珠，利用微孔的吸附特性及极大的比表面积，可做为良好的吸附载体材料。     

Effect of Bi2O3 addition on electron paramagnetic resonance, optical absorption, and conductivity in vanadyl-doped Li2O-K2O-Bi2O3-B2O3 glasses

Glasses with composition 15Li(2)O-15K(2)O-xBi(2)O(3)-(65 - x)-B(2)O(3)/5V(2)O(5) (3 ≤ x ≤ 15) have been prepared by the conventional melt quench technique. The electron paramagnetic resonance spectra of VO(2+) in these glasses have been recorded in the X-band frequency (≈9.3 GHz) at room temperature. The spin Hamiltonian parameters and covalency rates were evaluated. It was found that the V(4+) ions exist as vanadyl (VO(2+)) ions and are in an octahedral coordination with a tetragonal compression. The covalency rates (1 - α(2)) and (1 - γ(2)) indicate moderate covalency for the σ- and π-bonds. It was observed that the spin-Hamiltonian parameters depend slightly on the relative concentration of Bi(2)O(3). The optical properties of this glass system are studied from the optical absorption spectra recorded in the wavelength range 200-800 nm. The fundamental absorption edge has been identified from the optical absorption spectra. The values of optical band gap for indirect allowed transitions have been determined using available theories. The direct current electrical conductivity, σ, has been measured in the temperature range 373-573 K. The conductivity decreases with the increase in Bi(2)O(3) concentration. This has been discussed in terms of the decrease in the number of mobile ions and their mobility. An attempt is made to correlate the EPR, optical, and electrical results and to find the effect of Bi(2)O(3) content on these parameters.     

TiO2/SiO2气凝胶微球的制备及其表征

以TiOSO4和硅溶胶为原料, 加入甲酰胺作为干燥控制化学添加剂, 采用W/O乳状液中的溶胶-凝胶法制备TiO2/SiO2凝胶微球, 通过正硅酸乙酯母液浸泡、溶剂交换、陈化和常压干燥技术制备TiO2/SiO2气凝胶微球, 采用光学显微镜、SEM、TEM和BET比表面及孔分布测定等手段对所得样品进行表征. 典型的气凝胶微球样品是由粒径15 nm左右, 粒度分布相当均匀的球状纳米粒子构成的轻质纳米多孔材料, 表观密度为177 kg•m-3, 比表面积372 m2•g-1, 平均孔径22.78 nm, 孔隙率高达92.0％, 微球的宏观粒径为50 m. 依据制备条件的变化, TiO2/SiO2气凝胶微球的宏观粒径可控在10～200 m之间, 表观密度为150～300 kg•m-3, 比表面积为300～400 m2•g-1, 平均孔径在18.71～22.78 nm之间变化.     

Y_2O_3∶Eu~(3+)薄膜的制备及发光性能的研究

以稀土氧化物为原料,用溶胶-凝胶法制备前驱液,加入适量的聚乙烯醇做成膜物质,用浸渍拉提法在石英玻璃表面上得到均匀的薄膜,然后经过适当的干燥和热处理得到Y2O3∶Eu3+发光薄膜.讨论了Eu3+的掺杂浓度和热处理温度对薄膜发光性能的影响.试验表明:Eu3+的最佳掺杂浓度为8%(摩尔分数),薄膜的发光性能随热处理温度提高而增强,当热处理温度达到700℃后,薄膜的发光性能基本上稳定.同时用原子力显微镜和X射线衍射分析了薄膜的表面形貌和结构.     

Optical, electrical and dielectric properties of TiO2-SiO2 films prepared by a cost effective sol-gel process

Titanium dioxide (TiO(2)) and silicon dioxide (SiO(2)) thin films and their mixed films were synthesized by the sol-gel spin coating method using titanium tetra isopropoxide (TTIP) and tetra ethyl ortho silicate (TEOS) as the precursor materials for TiO(2) and SiO(2) respectively. The pure and composite films of TiO(2) and SiO(2) were deposited on glass and silicon substrates. The optical properties were studied for different compositions of TiO(2) and SiO(2) sols and the refractive index and optical band gap energies were estimated. MOS capacitors were fabricated using TiO(2) films on p-silicon (100) substrates. The current-voltage (I-V) and capacitance-voltage (C-V) characteristics were studied and the electrical resistivity and dielectric constant were estimated for the films annealed at 200°C for their possible use in optoelectronic applications.     

Structural, optical, physical and electrical properties of V2O5.SrO.B2O3 glasses

The present work aims to study the structure and variation of optical band gap, density and dc electrical conductivity in vanadium strontium borate glasses. The glass systems xV2O5.(40-x)SrO.60B2O3 and xV2O5.(60-x)B2O3.40SrO with x varying from 0 to 20 mol% were prepared by normal melt quench technique. Structural studies were made by recording IR transmission spectra. The fundamental absorption edge for all the glasses was analyzed in terms of the theory proposed by Davis and Mott. The position of absorption edge and hence the value of the optical band gap was found to depend on the semiconducting glass composition. The absorption in these glasses is believed to be associated with indirect transitions. The origin of Urbach energy is associated with the phonon-assisted indirect transitions. The change in both density and molar volume was discussed in terms of the structural modifications that take place in the glass matrix on addition of V2O5. dc conductivity of the glass systems is also reported. The change of conductivity and activation energy with composition indicates that the conduction process varies from ionic to polaronic one.     

具有辐射聚合能力的HfO2/SiO2溶胶-凝胶玻璃的制备及其X射线光刻性能研究

采用溶胶-凝胶方法制备了一种新颖的具有辐射聚合能力的HfO2/SiO2凝胶薄膜. 并采用X射线作曝光光源对薄膜进行了曝光, 通过FTIR的测试, 分析了薄膜曝光前后的结构变化. 结果表明, 该材料具有良好的辐射聚合能力. 采用XPS分析了薄膜的成分, 并证实了Hf元素的存在. 用椭偏仪测试了薄膜的折射率, 结果证实, 加入HfO2提高了体系的折射率. 利用其辐射聚合能力, 采用X射线通过掩模板进行曝光, 利用曝光部分与未曝光部分在溶剂中的溶解度差, 在薄膜上制备了高为0.8 μm、周期为1 μm的衍射光栅, 进一步证实了材料具有良好的辐射聚合能力.     

Surface properties of Ni-Pt/SiO2 catalysts for N2O decomposition and reduction by H2

The surface properties of bimetallic Ni-Pt/SiO2 catalysts with variable Ni/Ni + Pt atomic ratio (0.75, 0.50, and 0.25) were studied using N2O decomposition and N2O reduction by hydrogen reactions as probes. Catalysts were prepared by incipient wetness impregnation of the silica support with aqueous solutions of the metal precursors to a total metal loading of 2 wt %. For both model reactions, Pt/SiO2 catalyst was substantially more active than Ni/SiO2 catalyst. Mean particle size by TEM was about the same (in the range 6-8 nm) for all catalysts and truly bimetallic particles (more than 95%) were evidenced by EDS in the Ni-Pt/SiO2 catalysts. CO adsorption on the bimetallic catalysts showed differences in the linear CO absorption band as a function of the Ni/Pt atomic ratio. Bimetallic Ni-Pt/SiO2 catalysts showed, for the N2O decomposition, a catalytic behavior that points out an ensemble-size sensitive behavior for Ni-rich compositions. For the N2O + H2 reaction, the bimetallic catalysts were very active at low temperature. The following activity order at 300 K was observed: Ni75Pt25 > Ni25Pt75 approximately Ni50Pt50 > Pt. TOF values for these catalysts increased 2-5 times compared to the most active reference catalyst (Pt/SiO2). The enhancement of the activity in the Ni75Pt25 bimetallic catalysts is explained in terms of the presence of mixed Ni-Pt ensembles.     

Mechanism of RuO2 crystallization in borosilicate glass: an original in situ ESEM approach

Ruthenium, a fission product arising from the reprocessing of spent uranium oxide (UOX) fuel, crystallizes in the form of acicular RuO(2) particles in high-level waste containment glass matrices. These particles are responsible for significant modifications in the physicochemical behavior of the glass in the liquid state, and their formation mechanisms are a subject of investigation. The chemical reactions responsible for the crystallization of RuO(2) particles with acicular or polyhedral shape in simplified radioactive waste containment glass are described. In situ high-temperature environmental scanning electron microscopy (ESEM) is used to follow changes in morphology and composition of the ruthenium compounds formed by reactions at high temperature between a simplified RuO(2)-NaNO(3) precursor and a sodium borosilicate glass (SiO(2)-B(2)O(3)-Na(2)O). The key parameter in the formation of acicular or polyhedral RuO(2) crystals is the chemistry of the ruthenium compound under oxidized conditions (Ru(IV), Ru(V)). The precipitation of needle-shaped RuO(2) crystals in the melt might be associated with the formation of an intermediate Ru compound (Na(3)Ru(V)O(4)) before dissolution in the melt, allowing Ru concentration gradients. The formation of polyhedral crystals is the result of the direct incorporation of RuO(2) crystals in the melt followed by an Ostwald ripening mechanism.