Li_2O-B_2O_3-ZrO_2系统玻璃的结构研究

用径向分布函数和红外光谱分析方法研究了Li_2O-B_2O_3-ZrO_2和Li_2O-B_2O_3等系统玻璃的结构。得出了Li_2O-B_2O_3-Z_rO_2系统玻璃中的Zr~(4+)离子影响碱硼酸盐玻璃的网络结构。随着Z O_2含量的增加BO_3三角体转变为BO_4四面体,并形成含BO_4四面体较多的硼酸盐基团。在含Z O_2为10mol％的锂硼酸盐玻璃的RDF曲线中,第一峰的位置r_1=1.54A可能是~3B-φ(φ表示桥氧),~4B-φ和Z_r-O原子对距离的贡献;第二峰的位置r_2=2.28A是O—O;Li O和Z_r-O原子对距离的贡献;第三峰的位置r_3=3.30A是Zr-Z_r原子对距离。玻璃中的Z_r~(4+)离子作为网络修饰体以6配位状态填充于硼酸盐基因空隙中。     

B_2O_3-Li_2O-LiCl-Al_2O_3系统非晶态快离子导体

本文研究了B_2O_3—Li_2O—LiCl—Al_2O_3系统非晶态快离子导体的导电性。用红外光谱、X射线荧光分析术研究了该系统玻璃的结构,以及LiCl、Al_2O_3对本系统玻璃中Li~+离子导电性能的影响。Li_2O的加入,使硼氧三角体[BO_3]转变为硼氧四面体[BO_4],当Li_2O含量超过30mol％时,玻璃中主要是含[BO_4]较多的二硼酸盐基团。LiCl的加入,对玻璃结构没有明显的影响,其处于被网络骨架解离的状态。但随LiCl含量的增加,离子电导率迅速上升。引入Al_2O_3,使玻璃能在室温冷却条件下形成,且都使电导率下降,导电活化能升高。但高温下电导率下降并不明显。实验测得室温下离子电导率σ=6.2×10~(-6)Ω~(-1)cm~(-1),300℃时σ=6.8×10~(-3)Ω~(-1)cm~(-1),计算的导电活化能值为0.6～1.0eV。     

La_2O_3-Li_2O-B_2O_3三元系统玻璃的分子振动光谱研究

本文用群论方法分析了xLa_2O_3 20Li_2O·(80-x)B_2O_3三元系统玻璃,进行了拉曼与红外光谱测试,着重研究了La_2O_3对本系统结构的影响,发现了La_2O_3的作用与Li_2O相似,随着x增加,玻璃结构的演变过程为: 四硼酸盐基团—→二硼酸盐基团—→偏硼酸盐基团。在高La_2O_3情况下还产生焦硼酸盐和正硼酸盐基团,为探索锂快离子导体玻璃态新材料提供一定的基本认识。     

P_2O_5-Nb_2O_5-Li_2O系统非晶态的变色机理研究

本文采用拉曼、红外、径向分布函数及可见光谱分析了P_2O_5-Nb_2O_5-Li_2O三元系统玻璃的结构及铌离子价态,指出10Nb_2O_5·xP_2O_5·(90-x)Li_2O(x=40,45,50,55)系列玻璃中随x增加玻璃颜色由浅金黄变成蓝色,并不是由于铌离子配位变化引起的,而是由于Nb~(3+)的逐渐增多所致,并对变色机理进行了探讨。     

Li_2O-P_2O_5-V_2O_5系统非晶态的形成及结构研究

本文研究了Li_2O-P_2O_5-V_2O_5系统非晶态的生成,给出了本实验条件下该非晶态的形成范围。测量了试样的密度及转变温度,并利用红外光谱、拉曼光谱对该系统非晶态进行了结构分析。着重研究了Li_2O的引入对非晶材料结构的影响规律。当Li_2O<10mol％时主要起“积聚”网络作用,而Li_2O>10mol％时主要起松散网络作用。结构研究表明[PO_4]四面体及[VO_5]三角双锥体共同构成非晶态的网络骨架。而[VO_5]基因的特征振动ν_v=0的振动峰出现在1020～940cm~(-1)范围,随Li_2O的加入向低波数方向移动。文中还给出了该三元系统非晶态的结构模型示意图。     

STUDY OF THE MOLECULE VIBRATING SPECTRA OF THE TERNARY SYSTEM La_2O_3-LI_2O-B_2O_3 GLASSES

This paper deals with the ternary xLa_20_2·20Li_2O·(80-x)B_2O_3 glssses in terms of GroupTheory.By means of Raman spectra and Infrared spectra,the effects of La_2O_2 on the structureof the system are found to be similar to that of Li_2O.With the increase of x value,the transfor-ming process of the glass structure is:[B_8O_(12)]~(2-)——[B_4O_7]~(2-)——[BO_2]~(1-)If the content of La_2O_2 is higher,pyroborate and orthoborate groups would come into being.This is very useful to the study of new noncrystalline Li+-fastion conductors.     

Li_2O-Ta_2O_5-GeO_2非晶态系统的X射线研究

本文用X射线衍射技术研究了x·Li_2O·0.15Ta_2O_5(0.85—x)GeO_2三元系统的结构,求出了它们的径向分布函数(RDF)。利用RDF和权重因子求得的配位数定量地计算了玻璃中[GeO_4]和[GeO_6]的百分含量。结果表明:该三元系统存在着“错反常”现象。随着Li_2O的加入,玻璃中[GeO_4]部分转变为[GeO_6]。当Li_2O含量为25mol%时,[GeO_6]含量达到极大值,即[GeO_6]为24%。当继续加入Li_2O时,非桥氧的[GeO_4]增加,而不稳定的[GeO_6]减少。同时探讨了玻璃的结构模型。     

在Li_2O-P_2O_5二元系统玻璃中引入BaO对玻璃结构的影响

用径向分布函数(RDF)法、喇曼光谱和红外光谱研究了在Li_2OP_2O_5系统玻璃中引入Ba~(2 )离子取代Li~ 离子对玻璃结构的影响。测试表明,含钡锂磷酸盐玻璃的主要结构为以[P0_4]为单元的链状网络结构。RDF曲线可以提供关于Ba~(2 )离子分布的重要信息。RDF曲线上的4.00—4.15A和7.15—7.45A特征峰位表示Ba-Ba近邻距离。键角ф_(o-p-o)和力常数F_(m-o)的错综变化,在喇曼光谱上表现为玻璃主要结构(如[PO_4]链)特征峰的波数和强度发生微小的变化。玻璃中B~(2 )离子的存在使连接非桥氧的方向键有所加强,将影响磷酸盐链之间离子键的强度,从而导致玻璃的一些物理性质的变化。     

三元稀土固体超强酸催化剂SO_4~(2-)/Nd_2O_3-ZrO_2-Fe_2O_3的制备工艺研究

采用共沉淀法制备了三元稀土固体超强酸催化剂SO_4~(2-)/Nd_2O_3-ZrO_2-Fe_2O_3,并将其应用于乙酸乙酯的催化合成反应中.以乙酸乙酯的合成酯化率为研究指标,探索了制备三元稀土固体超强酸催化剂42-/Nd_2O_3-ZrO_2-Fe_2O_3的条件.结果表明最佳制备工艺为:焙烧温度550℃,浸渍液浓度1.25 mol·L~(-1),陈化温度-15℃.在此条件下,乙酸乙酯合成酯化率达98.0%以上.同时通过红外光谱法、X射线衍射法、透射电镜法对三元稀土固体超强酸催化剂SO_4~(2-)/Nd_2O_3-ZrO_2-Fe_2O_3进行了表征.结果表明:催化剂表面与SO_4~(2-)形成桥式双配位,具有高催化性能;表面有一定程度的晶态结构,其反应为表面催化;该催化剂其平均粒径小于17 nm,处于纳米尺度.     

B_2O_3—Al_2O_3—PbO玻璃组成和物化性质的研究

本文研究了B_2O_3—Al_2O_3—PbO玻璃中引入La2O3、SiO2、Sb2O3、Ga2O3后，TF光学玻璃化学稳定性及相对部分色散Pg·F。论证了B2O3－Al2O3－PbO光学玻璃光学性质，化学稳定性和结构关系。TF光学玻璃在3．5L铂坩埚中熔制。     

在V_2O_5、Sb_2O_3、Bi_2O_3、Fe_2O_3、K_2O/Al_2O_3催化剂上邻二甲苯的氨氧化

本文论述了邻二甲苯氨氧化合成邻苯二甲腈的最佳工艺条件,载在高温热处理的三氧化二铝上的 V_2O_s、Sb_2O_3、Bi_2O_3、Fe_2O_3、K_2O 催化剂,对生成邻苯二甲腈表现出良好的活性及选择性,其选择率>95%。催化剂的酸度是一个关键因素.     

Cr_2O_3、Al_2O_3掺杂V_2O_3系PTC陶瓷的制备与特性

本文在还原性气氛（Ｈ２）中制备出Ｃｒ２Ｏ３、Ａｌ２Ｏ３掺杂的Ｖ２Ｏ３系ＰＴＣ陶瓷。测量了材料的电阻率、采用ＸＲＤ、ＳＥＭ分析了材料的结构。并初步讨论了液氮淬冷对Ｖ２Ｏ３系ＰＴＣ陶瓷的结构及ＰＴＣ性能的影响。     

Fe_2O_3-Mn_2O_3-SiO_2系统涂层的研究

本文概述了用溶胶-凝胶法制备 Fe_2O_3-Mn_2O_3-SiO_2系统涂层的工艺,并且运用红外吸收光谱、综合热分析和透射电镜等分析手段,研究了该涂层由凝胶向玻璃态的转化过程、涂层的显微结构特点和着色机理。结果表明,凝胶经加热排除多余溶剂和缩聚反应,逐渐转变为固态。涂层中含有 Fe_2O_2和 Mn_2O_3的胶粒,因此出现光散射和光吸收着色。     

Structure of Bi_2O_3-ZnO-B_2O_3 system low-melting sealing glass

Bi2O3-ZnO-B2O3 system glass is a kind of lead-free low melting sealing glasses.The structure of Bi2O3-ZnO-B2O3 system low-melting sealing glass was investigated by DSC,FT-IR,XRD and SEM.The results show that with the increase of B2O3 content,the transition temperature Tg and softening temperature Tf of Bi2O3-ZnO-B2O3 system low-melting sealing glasses increase,which leads to the liquid phase precipitation temperature increasing and promotes the structure stability in the glass.With increasing the heat treatment temperature,a large number of liquid phases appear in samples and the sinter efficiency of the samples increases.The FT-IR spectra of the glasses show the presence of some bands that are assigned to vibrations of Bi-O bond from [BO3] pyramidal and [BiO6] octahedral units and B-O from [BO3] and [BO4] units.With the decrease of B2O3 content,the crystallization tendency of the glass increases.In glass samples B1 and B2,crystallization starts at 460℃ and 540℃,respectively.Both of them precipitate Bi24B2O39 phases.     

Effect of ZnO-B_2O_3 Glass Addition on the Microwave Dielectric Properties of BaO-Nd_2O_3-TiO_2-Bi_2O_3 System

The effect of ZnO-B2O3(ZB) glass addition on the sintering behavior, microstructures and microwave dielectric properties of BaO-Nd2O3-TiO2-Bi2O3 (BNTB) system was investigated with the aid of X-ray diffraction, scanning electron microscopy and capacitance meter. It is found that the ZB glass addition, acting as a sintering aid, can effectively lower the sintering temperature of BNTB system to 850 ℃. The dielectric constant of BNTB-ZB ceramics increases with the increase of soaking time and the value of dielectric loss decreased with increasing soak time. The optical dielectric properties at 1 GHz of ε=74, tan δ=4×10-4, and TCC=25 ppm/℃ were obtained for the BNTB system doped with 25 wt% ZB glass sintered at 850 ℃ for 2 h, representing that the BNTB-ZB ceramics could be promising for multilayer low temperature co-fired ceramics applications.     

Reduction mechanism of Fe_2O_3-Cr_2O_3-NiO system by carbon

Isothermal experiments on the reduction of Fe_2O_3-Cr_2O_3-NiO(molar ratio of Fe-to-Cr-to-Ni is 3:2:2)by graphite were carried out at 1350–1550°C,and effects of various factors on reduction degree were studied.The results show that the reaction rate of the Fe_2O_3-Cr_2O_3-NiO system is fast during the initial period(reduction degree,α38%),and then the rate decreases until the end of the reduction.Factors such as temperature,carbon content,sample size have a more significant effect during the final stage(α38%).The metallic product formed at the initial stage(a Fe-Ni alloy)greatly promotes the reduction of Cr2O3 at the final stage.Further,during the reduction of Fe_2O_3-Cr_2O_3-NiO by carbon,interfacial reaction is the rate-controlling step and g(α)=1-(1-α)0.5 is the reaction mechanism for the initial stage,whereas two-dimensional diffusion is the rate-controlling step and f(α)=α+(1-α)ln(1-α)is the reaction mechanism for the final stage.The apparent activation energies are 55.43 k J/mol and 174.54 k J/mol for the initial and the final stages,respectively.     

无压烧结Si_3N_4－MgAl_2O_4－Al_2O_3系复合材料

本文对ｓｉ＿３Ｎ＿４－ＭｇＡｌ＿２Ｏ＿４－Ａｌ＿２Ｏ＿３系复合材料的无压烧结进行了研究。讨论了Ａ１＿２Ｏ＿３含量对材料性能的影响及烧结工艺对材料性能和显微结构的相互关系。实验表明：两段法烧结可以得到性能良好的Ｓｉ＿３Ｎ＿４－ＭｇＡｌ＿２Ｏ＿４－Ａｌ＿２Ｏ＿３复合材料     

组成对Li_2O-Bi_2O_3-WO_3-B_2O_3系统玻璃性能的影响

采用传统的熔融冷却法制备了Li2O-Bi2O3-WO3-B2O3系统玻璃,对玻璃的电导率、质量密度和硬度进行了研究。结果表明,在Li2O-Bi2O3-WO3-B2O3系统玻璃中,固定n（Bi）：n（B）=3：2,当Li2O摩尔分数保持不变时,随着WO3摩尔分数的增加,玻璃的质量密度增大,硬度减小;当WO3摩尔分数保持不变时,随着Li2O摩尔分数的增加,玻璃的质量密度和硬度先增大后减小,在Li2O摩尔分数为13％时达到最大值,出现了硼反常现象,质量密度最大值为6．6g／cm^3,硬度最大值为401．6HV。     

Bi_2O_3-P_2O_5二元系统玻璃性能

采用高温熔融的方法制备xBi_2O_3-(100-x)P_2O_5二元系统玻璃,研究了Bi_2O_3含量变化对该体系玻璃的结构、热膨胀系数、密度和化学稳定性等的影响。在二元系统中随着Bi_2O_3含量的增加,熔融温度不断升高。当Bi_2O_3摩尔分数达到30%,在1 200℃下熔制且保温2h的玻璃液均化程度高、成玻性能良好,化学稳定性达到最好。随着Bi_2O_3含量的增加,热膨胀系数呈先减小后增大的趋势,在Bi_2O_3摩尔分数为25%出现最小值。     

Oxidative Desulfurization of DBT with H_2O_2 over 3DOM H_3PW_(12)O_(40)/Al_2O_3 Catalyst

A series of heteropoly acid (HPA) based Al_2O_3 catalysts with three-dimensional ordered (3DOM) structure were synthesized by colloidal crystal template method.Interconnected macropores (250 nm) could be clearly observed by scanning electron microscope (SEM) and transmission electron microscope (TEM).Mesopores could be detected by N_2 adsorption-desorption isotherms which further confirmed the 3DOM structural characteristics of catalyst.Moreover,Keggin-type HPW was highly dispersed in the Al_2O_3 framework,which suggested by powder X-ray diffraction (XRD) and Fourier transform infrared spectra (FT-IR) results.The oxidation desulfurization (ODS) performance of 3DOM H_3PW_(12)O_(40)/Al_2O_3 of refractory sulphur compounds was evaluated in the presence of hydrogen peroxide.It oxidized 98.5% of dibenzothiophene (DBT) into corresponding sulfone within 3 h,which exhibited superior ODS performance than corresponding mesoporous and microporous H_3PW_(12)O_(40)/Al_2O_3 catalyst.The enhancement of ODS efficiency is related to the improvement of mass transfer of DBT in the pore channel resulting from the interconnected 3DOM structure.Furthermore,the as-prepared catalyst still demonstrates outstanding cycle performance after 6 runs,which could be easily recovered from the model fuel.