Ba—K—Bi—O和Ba—K—Pb—O氧化物的磺量滴定

本文提出了碘量法滴定Ｂａ－Ｋ－Ｂｉ－Ｏ和Ｂａ－Ｋ－Ｐｂ－Ｏ氧化物中Ｂａ和Ｐｂ的名义价态，然后据此计算这些氧化物中Ｋ和Ｂａ含量的方法。     

BaFeO3和BaCeO3钙钛矿型氧化物的储氮性能

 采用改进的溶胶－凝胶法制备了Ba－Fe－O（Ba／Fe原子比为0．5），Ba－Ce－O（Ba／Ce原子比为1）和Ba－Sn－O（Ba／Sn原子比为1）氧化物，并考察了其储氮性能．结果表明，750℃焙烧的Ba－Fe－O样品，在400℃下的NOx储存容量（NSC）最大，其次为900℃焙烧的Ba－Ce－O样品；相同温度焙烧的样品，在400℃下的NSC均大于200℃下的NSC．XRD测试结果表明，750℃焙烧的Ba－Fe－O样品的缺陷钙钛矿BaFeO3－δ可能是储存NOx的主要活性相，而Ba－Ce－O和Ba－Sn－O样品储存NOx的活性相分别为钙钛矿型BaCeO3和BaSnO3．BET测定结果表明，样品的比表面积均较小．用FT－IR分析了Ba－Fe－O样品上储存的NOx物种．讨论了NSC大小与吸收温度、NOx吸收物种及样品物相之间的关系．     

Nd1＋xBa2—xCu3O7—δ超导体的热处理

通过对Nd1 xBa2-xCu3O7-δ的两种样品（烧结样品和区域熔炼样品）的XRD谱图分析,研究了高温氩气氛下热处理对样品中Nd对Ba的取代值x的影响,同时比较下不同样品的Tc和Jc值。 研究表明,氩气下950度热处理可以减少Nd对Ba的取代,TcJc都有不同程度的提高。对不同固溶液度x值的Nd1 xBa2-xCu3O7－δ进行吸氧热处理,样品在热处理前后分别为XRD分析,从XRD谱图可以看出,当X＜0．4时,样品经吸氧后可以从四方相转变为正交相,而当X＞0．4时,样品虽经长时间吸氧也不能使其从四方相转变为正交相。     

示波极谱法测定硅锶钡铁合金中的锶和钡

Sr—Si—Fe合金中含1—5％的Sr,现有的化学分析方法是采用EDTA络合滴定。而在冶炼过程中尚需加入大致相等量的Ba,故此需Ba、Sr同时测定。其它方法分析如此含量的Ba、Sr总还存在一些困难。本文采用示波极谱法,以四甲基碘化铵为支持电解质,成功的测定了硅锶钡铁合金中的Sr和Ba。峰值电位Ba为-1.95V,Sr为-2.15V(vs SCE),Sr或Ba浓度在0.1—     

M(TNR)·H2O的热分解机理

本文用TG—DTA、DSC、IR和X光衍射分析考察了三硝基间苯二酚金属盐M(TNR)·H_2O(M=Pb、1/4Pb3/4Ba、Ba)的热行为及其热分解机理。结果表明,M(TNR)·H_2O晶体的热分解过程均分三个阶段进行。即脱水阶段;脱硝逸出NO_2伴随苯环碎裂成凝聚相产物的阶段和凝聚相产物分别生成PbO和少量碳;BaCO_3、PbO和少量碳;BaCO_3的阶段。     

氧化铝对Fe－Cu－Zn－K－Al低碳醇合成催化剂性能的影响

 采用N2吸咐，TPR和XRD等表征手段对高温熔融法制备的Fe－Cu－Zn－K－Al催化剂中氧化铝的作用进行了研究．结果表明，当比表面积低于4．0m2／g时，催化剂性能受比表面积的影响非常明显．少量的Al2O3即可有效地增加催化剂的比表面积，提高醇的收率和C2＋OH的选择性；大量的Al2O3虽然能使催化剂的比表面积有所增加，但醇的收率和C2＋OH选择性却显著降低．这是Fe－Cu－Zn－K－Al催化剂中Al2O3同时具有物理作用和化学作用所致．物理作用能有效地增加还原后催化剂的比表面积，提高金属利用率，分散催化剂的活性组分，使其更容易还原，进而提高催化剂活性和选择性．化学作用影响到催化剂的电子性质，从而导致催化剂的活性和选择性降低．TPR和XRD结果表明，在Fe－Cu－Zn－K－Al催化剂中，助剂Al2O3的作用随着其含量的变化而有所不同．当Al2O3含量较低时，其物理作用是主要的；随着Al2O3含量的增加，其化学作用更为明显，甚至导致新物相AlFeO3生成，进而影响催化剂的催化性能．     

助剂钾在Ni－Co－O、Zn－Co－O尖晶石催化剂中的作用

助剂钾在Ｎｉ－Ｃｏ－Ｏ、Ｚｎ－Ｃｏ－Ｏ尖晶石催化剂中的作用陈敏，罗孟飞，袁贤鑫（杭州大学催化研究所杭州３１００２８）关键词助剂钾，Ｎｉ－Ｃｏ－Ｏ，Ｚｎ－Ｃｏ－Ｏ，复合氧化物在多相催化领域中，尖晶石复合氧化物作为催化剂，有很大的实用性，Ｍａｒｇｏｌｉｓ...     

YBa2Cu3O7-x高Tc超导体的热转变

自朱经武等最先报道液氮温区Y—Ba—Cu—O体系超导体以来，世界上涌现第二次高Tc超导体研究热潮。材料的烧结与退火均在高温下进行，尤以退火条件对超导性能好坏影响为大。因此，高温热转变的研究对于优良材料的获得及超导机制的认识都至为重要。迄今     

钡铁氧体纳米复合材料的制备及其微波吸收性能

采用聚乙二醇(PEG)凝胶法制备了Ba(Zn1－xCox)2Fe16O27复合氧化物纳米材料，用X射线衍射分析对产物进行了表征.将制得的材料与传统的微波吸收剂铁粉结合起来，制成双层复合的吸波涂层，进行测试.实验结果表明，所制材料对微波具有良好的吸收性能.并进一步对纳米复合材料的吸波机理进行了探讨.     

ICP—AES测定钯—钡合金中常量钡

本文采用ＩＣＰ－ＡＥＳ法测定钯－钡合金中常量钡。考察了其体及无机酸的存在对钡发射线强度的影响，采用标准曲线法对含量分别为０．５９％和２６．０４％的两个试样进行了测定，结果满意。     

Ba-K-Bi-O超导体熔盐阳极电结晶研究

用ＸＰＳ和ＸＲＤ表征了Ｂａ－Ｋ－Ｂｉ－Ｏ超导体熔盐电结晶的阳极和阴 极产物，用ＳＥＭ分析了Ｂａ－Ｋ－Ｂｉ－Ｏ单生长形态。结果表明，阳极产物是Ｂａ－Ｋ－Ｂｉ－Ｏ超导体单晶，以台阶式方式生长。－Ｋ－Ｂ－     

Ba－K－Bi－O超导体的化学稳定性

Ba-K-Bi-O (BKBO)超导体的导电性和超导性各向同性,相干长度长,制备温度低,因此它有良好的应用前景.但在BKBO超导器件走向实用化时,还必须了解它在环境介质中的化学稳定性,以便采取相应的保护措施.本文目的就是研究BKBO在各种介质中的稳定性及其作用机理.用电化学法在BKBO膜上制成了聚毗咯((PPy)和聚唾吩((PTh)膜,为BKBO超导器件的保护提供了新思路.     

电感耦合等离子体发射光谱法测定植物中硫含量

采用电感耦合等离子体发射光谱法(ICP-AES)探讨植物中硫含量的测定。以HNO3-HClO4消解植物试样,优化全谱型ICP-AES分析条件测定植物中硫的含量,检测限为5.7ng/mL(180.7nm)和8.6ng/mL(182.0nm)。用该方法测定灌木枝叶和茶叶植物标准物质中的硫含量,测定结果均在标称值范围内,连续测定11个平行样测定结果的相对标准偏差均小于2.5%。     

Influence of a Nonionic Surfactant (Triton X-100) on Contaminant Distribution between Water and Several Soil Solids

The influence of a nonionic surfactant (Triton X-100) on the contaminant distribution coefficients in solid-water mixtures was determined for a number of relatively nonpolar compounds (contaminants) on several natural solids. The studied compounds consisted of BTEX (benzene, toluene, ethylbenzene, and p-xylene) and chlorinated pesticides (lindane, alpha-BHC, and heptachlor epoxide), which span several orders of magnitude in water solubility (S(w)); the solid samples comprised a bentonite, a peat, and two other soils, which cover a wide range of solid organic matter (SOM) content. The applied surfactant concentrations (X) ranged from below the (nominal) CMC to 2-3 times the CMC. For relatively water-soluble BTEX compounds, the distribution coefficients with surfactant (K(d)*) all exceeded those without surfactant (K(d)); the K(d)*/K(d) ratios increased with increasing S(w) from p-xylene to benzene on each solid at a given X, with increasing X for each compound on a solid, and with decreasing solid SOM content for each compound over the range of X studied. For the less-soluble pesticides, the K(d)*/K(d) ratios exhibited a large increase with X for bentonite, a marginal change (increase or decrease) for a soil of 2.4% SOM, and a moderate-to-large decrease for two soils of 14.8% and 86.4% SOM. These unique observations were rationalized in terms of the properties of the compound, the amount of surfactant sorbed on the solid, the enhanced solubilization of the compound by surfactant in water, and the relative effects of the surfactant when adsorbed on minerals and when partitioned into SOM. Copyright 2000 Academic Press.     

High Temperature Phase Transitions in Na_xCoO_2 Materials

1 INTRODUCTION In recent years, much attention has been focused on the NaxCoO2 system due to its notable properties and potential technologic applications as a cathode material in high-energy density, reversible solid state battery systems[1, 2]. Recently, large thermoelectric power[3～6] in NaxCoO2 and superconductivity (～4 K) in hydrated NaxCoO2yH2O (x = 0.35, y = 1.33) ma- terial have been observed[7]. This hydrated layered phase is the first 3d-transition metal oxide with superco…     

层状钴氧化物Bi2-xAgxSr2Co2O8-δ的高温热电性能及XPS研究

采用固相反应法制备了组成为Bi_2-xAg_xSr₂Co₂O_8-δ(x=0.0, 0.4, 0.8,略写为BAC-222)的层状钴氧化物陶瓷。利用X-射线光电子能谱考察该类化合物的电子结构,结果表明钴离子以Co³⁺和Co⁴⁺混合价态形式存在,n_Co⁴⁺/n_Co³⁺的比例随着Ag掺杂的量增加而增加。O1s光电子谱显示在所有样品中均存在点阵氧和吸附氧。热电性能测试结果显示,随着Ag掺杂量的增加,电导率显著增加而Seebeck系数几乎保持不变,Ag的引入极大的影响了BAC-222的电子输运性质,其功率因子在1 123 K时达到了1.23×10^-4 W·m^-1·K^-2,是一种具有很好应用前景的热电材料。     

Validation of a Reversed-Phase Liquid Chromatographic Method for the Determination of Metronidazole in Transparent Oil-Water-Gel Formulations

A high performance liquid chromatographic (HPLC) method for the determination of metronidazole in new gel formulations was developed and validated according to the recommendations of the International Harmonization Conference. An adaptation of the method described for metronidazole determination in plasma has been used, and the step of extraction has been developed. The method was demonstrated to be linear over a range of 60–140% of nominal label claim, accurate (100.08±0.63%) and precise (0.67% for intra-assay and 1.68% for inter-assay). Single point calibration was chosen for analysis because of its simplicity and wide use in the pharmaceutical industry for content uniformity analysis.     

Dynamic mechanical properties of a gel of cellulose nitrate in diethyl phthalate: Reduced variable analysis in terms of amorphous and crystalline phases

A phenomenological theory is presented to extend the method of reduced variables for the effects of both temperature and changing degree of crystallinity on the linear viscoelastic properties of solutions of crystalline polymers. The vertical and the horizontal shift factors, which are both obtainable in the course of analysis of the experimental data, are correlated with the concentration of the solution and the volume fraction of the crystalline phase, and the fractional free volume of the system, respectively. Dynamic mechanical properties of a gel of cellulose nitrate (nitrogen content, 12.6%) in diethyl phthalate with a nominal concentration of 18% by weight were obtained in the transition region from glasslike to rubberlike consistency and also in the rubbery plateau region by employing the Fitzgerald apparatus and a freely oscillating torsion pendulum over the temperature range from ?49 to 65°C. Application of the new reduction method to the experimental data was found to be quite successful, and it was shown that in general the degree of crystallinity in the system (and hence also the concentration of polymer in the amorphous phase) can depend on both temperature and thermal history. The dynamic mechanical data of a gel of different nominal concentration (23% by weight) previously obtained by Plazek were reanalyzed in terms of the method herein given.     

Bi(Pb)-Sr-Ca-Cu-O体系中110K超导相的制备和结构研究

The stable superconducting phase with T_c 110 K has been prepared in samples of nominal composition (Bi_(2-x)Pb_x)Sr_2Ca_2Cu_3O_y and (Bi_(2-x)Pb_x)Sr_2Ca_3Cu_5O_y x=0.2, 0.4, 0.6. The crystal strucuure of the superconducting phase (Bi_1.8Pb_0.2)Sr_2Ca_2Cu_3O_y with T_c 106.3 K has been determined in the sample of nominal composition (Bi_1.8Pb_0.2)Sr_2Ca_3Cu_5O_y. It is a nine decker perovskite arrangement by incorporating two extra layers CaCuO_2 in each cell of Bi_2Ca_1Cu_2O_y. The plane of CuO_2 is planar in incorporating layer CaCuO_2. Speace group D~1_(2h)-Pmmm was assigned. Adding Pb is in Bi site, and atomic radius and atomic valence in Bi site was modified, so that it is able to stabilize crystal structure and progress superconducting properties.