从废铁屑电解制备纯铁及其腐蚀特性

以工业废铁屑作原料制备高纯度电解铁,并优化了在氯化物溶液中的电解工艺条件,所得样品纯度最高可达到99.983%.通过SEM断面形貌观察,该电解铁样品非常致密.交流阻抗及腐蚀速率测定表明,电解铁的纯度越高,其耐腐蚀性能越好.     

旋涂水溶液前驱体制备氧化锌薄膜及其性质

通过旋涂法, 采用Zn(OAc)2·2H2O和聚环氧乙烷(PEO)的水溶液为前驱体在不同的热处理温度下制备了ZnO薄膜. PEO的加入增加了溶液的成膜性, 其较低的热分解温度有利于制得纯净的ZnO薄膜. 文中考察了在不同热处理温度下制备的ZnO薄膜的形貌、结晶性、带隙(Eg)以及电导性. 原子力显微镜(AFM)测试表明在热处理温度为400、450和500 ℃制备的ZnO薄膜的粗糙度均方根值分别为3.3、2.7和3.6 nm. 采用透射电子显微镜(TEM)测试发现ZnO薄膜中含有大量纳晶粒子. 通过测试ZnO薄膜的UV-Vis吸收光谱, 根据薄膜位于373 nm处的吸收带边计算得到ZnO的带隙为3.3 eV. 通过对薄膜的电流-电压(I-V)曲线的测试计算得到在热处理温度为400、450和500 ℃制备的ZnO薄膜的电阻率分别为3.3×109、2.7×109和6.6×109 Ω·cm. 450 ℃时制备的ZnO薄膜的电阻率最小, 主要是由于较高的热处理温度有利于提高薄膜的纯度、密度和吸附氧. 而纯度较高、密度较大的薄膜电阻率比较小; 吸附氧含量增加, 晶界势垒增大, 电阻率增大. 因此在纯度和吸附氧的双重作用下450 ℃时制备的ZnO薄膜的电阻率最小, 而500 ℃时制备的ZnO薄膜的电阻率最大.     

铁酸盐MFe2O4的氢气还原热失重分析和氧缺位铁酸盐MFe2O4-δ的制备条件

使用程序升温(298-843K)和等温(523K、573K和623K)热失重分析研究了多种方法制备的尖晶石结构铁酸盐MFe₂O₄(M=Fe、 Mn、 Co、 Ni)的还原行为,讨论了铁酸盐的制备方法、粒径和比表面积对其还原性能的影响。根据程序升温过程中和等温还原下铁酸盐的失重量分别定量地测定了其活化速度和失氧速度,得出了制备氧缺位铁酸盐MFe₂O_4-δ(0<δ≤1)的最佳温度和时间。     

电解法制备K_2FeO_4过程添加剂的筛选

应用电解法,并于阳极电解液中分别加入KIO4等不同种类添加剂制备K2FeO4,考察添加剂对电流效率以及FeO42-稳定性的影响规律,产品K2FeO4的结构形貌由XRD、SEM表征.结果表明,KIO4是比较理想的添加剂,在阳极液中添加质量比为0.02%的KIO4,电解1h后,电流效率可提高31.6%,K2FeO4产品的纯度相应提高了3.85%.     

类钙钛矿化合物(La0.8-xCexSr0.2)0.97MnO3的电磁性能研究

探索性地研究了由内含不同程度CeO2的廉价原料--La2O3制备的, 名义成分为 （ La0.8-xCex Sr0.2）0.97MnO3 （x=0～0.26） 类钙钛矿锰氧化物的相结构、电磁性能, 及其作为固体氧化物燃料电池（SOFC）空气极材料的可能性. 实验显示, 样品中除了磁性的钙钛矿相外, 均出现了非磁性的Mn3O4相和不同程度的CeO2相;随着制备样品的原材料La2O3纯度的不同, 样品的电阻率、磁电阻比等电磁特性也随之发生明显的变化;样品在1 T磁场下的室温磁电阻比的范围可达-3%～-14%;对x=0, 0.037, 0.26的样品, 其电导率在600 K以上高温区均表现出较好的温度稳定性, 表明其作为SOFC空气极材料的可行性.     

电解条件对电化学法制备FeO42-的影响

以铁丝网作阳极,应用电解氧化法制备FeO42-溶液,并合成固体K2FeO4.研究电解条件(如搅拌、超声、静置、温度、电流密度等)对该制备过程电流效率的影响规律.结果表明:以14 mol/L NaOH作电解液,于30℃、10 mA.cm-2及搅拌作用下电解,可获得较高的电流效率.     

氧缺位铁酸盐MFe2O4-δ的性质研究

使用XRD、M(o)ssbauer谱及化学组成分析考察了氧缺位铁酸盐MFe2O4-δ(δ＞0,M＝Fe,Co,Mn,Ni)的晶格常数、磁性、稳定性及还原性.结果表明,氧缺位铁酸盐MFe2O4-δ(δ＞0)的晶格常数比MFe2O4+δ(δ≥0)的大,M(o)ssbauer谱内磁场却更小.MFe2O4-δ(δ＞0)随着氧缺位程度δ的增大,晶格常数增大,内磁场减小.MFe2O4-δ在室温下空气中是不稳定的,只能在惰性气体中低温(＜673K)下稳定存在.MFe2O4-δ具有较强的还原能力,在573K下能将CO2还原成C.     

Na3AlF6-LiF熔盐体系中硅的电沉积行为

研究了Na₃AlF₆-LiF体系中硅沉积的电化学行为及影响因素, 并分别采用电解沉积和电解精炼方法获得了单质硅. 结果表明: Si(IV)的电化学还原过程分步进行, 在有单质硅存在的情况下, 还发生反应Si(IV)+Si=2Si(II); 一般情况下Al的析出电位比Si要负, 但在电极表面Si离子匮乏的情况下, Al会与Si共沉积; 固态电极上恒流电解沉积硅呈颗粒状并与电解质夹杂, 通过分离可以获得单质硅, 所获硅纯度高于99.9%. 电解精炼在大电流密度条件下可以稳定进行, 阳极电流效率高于95%, 电解精炼硅纯度比直接电沉积硅纯度有明显提高.     

钙钛矿型稀土锰氧化物La_(0.7)Sr_(0.3)Fe_xMn_(1-x)O_3的磁性和巨磁电阻效应

采用溶胶 凝胶工艺制备了La0 .7Sr0 .3FexMn1 -xO3化合物 ,研究Fe掺杂对材料的导电性能、磁性能、磁电阻性能的影响。发现随Fe含量的增加 ,材料的电阻率提高 ,铁磁居里温度 (TC)下降 ,巨磁电阻效应增强。观察到x =0 0 5和x =0 0 8的样品的电阻率随温度变化曲线出现双峰。对于x =0 0 8的样品 ,在室温附近磁电阻达到 18% (8× 10 5 A·m- 1 外场 )。对于x >0 0 8的样品 ,金属 绝缘体转变温度均比相应的铁磁 顺磁转变温度低 5 0～ 80K     

乙酰胺-尿素-NaBr熔体中Gd-Ni合金的电化学制备

熔盐电解法制取稀土合金功能材料具有低成本等优点.本文选取353 K的乙酰胺-尿素-NaB r熔体,应用循环伏安法研究镍于该熔体(含0.063 mol.L-3N iC l2)、Pt、Cu电极上的还原.实验表明,N i(Ⅱ)+2 eN i(0)是一步完全不可逆反应,测得在Pt上N i(Ⅱ)的传递系数α=0.28,扩散系数D0=4.63×10-5cm2.s-1,Cu上α=0.22,D0=6.05×10-7cm2.s-1.以Cu作基体,Gd(Ⅲ)于该熔体不能单独还原为Gd(0),但可以被N i(Ⅱ)诱导共沉积.由恒电位法电解得到的Gd-N i合金,Gd(0)的含量随电解电位、Gd(Ⅲ)/N i(Ⅱ)摩尔比及电解时间的变化而变化.控制电解电位为-0.75 V,Gd(Ⅲ)/N i(Ⅱ)摩尔比为1∶1,电解20 m in.所得合金膜是非晶态的.     

Adsorption of A Multifunctional Additive (ZnDTC) Onto Iron and Iron(III) Oxide from n-Decane

The adsorption of zinc diisooctylodithiocarbamate (ZnDTC) onto iron and iron(III) oxide from n-decane solution was studied. The adsorption isotherms were determined together with the variation of the apparent differential molar enthalpy of displacement for ZnDTC on both adsorbents at 298 K. The shapes of the iostherms for the adsorption of dithiocarbamate on iron and iron(III) oxide are quite different, especially in the low coverage ratio. The corresponding differential molar enthalpies of displacement for the two studied systems are exothermic. On iron, the very high exothermic values indicate a process of ZnDTC chemisorption, while on iron(III) oxide, the much lower enthalpic effects are characteristic of physisorption.     

SINGLET-TRIPLET SPIN TRANSITION IN AN IRON(II) COMPLEX OF 1,10-PHENANTHROLINE-2-CARBOTHIOAMIDE

Abstract

The ⁵⁷Fe Mössbauer effect for the solid complex FeLCl₂·H₂O (L=10-phenanthroline-2-carbothioamide) has been studied between 4.2°K and 298°K. Two overlapping doublets (I and II) are observed, their relative intensity being strongly temperature dependent. The doublets are characterized by δE_Q(I)=0.53 mm sec^?1, δ^IS(I)=+ 0.22 mm sec^?1 and δE_Q(II)=1.33 mm sec^?1, δ^IS(II)=+0.23 mm sec^?1 at 4.2°K. In conjunction with magnetic data, the Mössbauer spectra are interpreted in terms of a singlet-triplet spin transition of the central iron(II) ion. In an applied magnetic field at 4.2°K, H_int=0, V_ZZ(I)>0, and V_ZZ(II)>0. The results are consistent with optical electronic and infrared vibrational spectra.     

Temperature dependence of hydrogen overvoltage on nickel and iron in acid solution

The temperature dependence of hydrogen overvoltage on mechanically and chemically polished nickel electrodes, on iron armco, and iron of high purity in 0.25 M H₂SO₄ are studied in the interval of temperatures 298–278 K. It is established that the influence of temperature on the slope of Tafel line depends essentially on the type of electrodes. The apparent energy of activationE and pre-exponential factorB are determined. The results show an important role of the electrode surface treatment and purity of the metal in the determination of energetic parameters of the hydrogen evolution reaction. The most striking result is that in the case of nickel electrodes with mechanically polished surfaceE increases andB decreases with the increase of overvoltage. Some aspects of nonclassical behavior of electrodes studied are discussed. Dedicated to the ninetieth anniversary of Ya.M. Kolotyrkin’s birth.     

Molecular alloy with diluted magnetic moments-molecular Kondo system

[Ni(1-x)Cu(x)(tmdt)(2)] (tmdt = trimethylenetetrathiafulvalenedithiolate) was prepared for realizing molecular Kondo systems. Magnetic moments (S = (1)/(2)) are considered to exist at the central {CuS(4)} parts of Cu(tmdt)(2) molecules. The χT-versus-T curve of the system with x ≈ 0.15 showed a broad peak at ~10 K. The decrease in the χT value below 10 K is consistent with a singlet ground state, as expected for a Kondo system. However, in the system with x ≈ 0.27, the χT value decreased when the temperature was lowered to 2 K, indicating antiferromagnetic interactions between magnetic moments through π-d interactions. Although the susceptibility anomaly suggested that the π-d interactions become important at T < 20 K, the observed resistivity (ρ(obs)) showed no resistivity minimum characteristic of a Kondo system down to 4.2 K. However, the differential resistivity Δρ(T) = ρ(obs) - ρ(L)(T) showed a logarithmic resistivity increase at 8-20 K with decreasing temperature, where ρ(L)(T) is a fitted function of ρ(obs) obtained at T > 50 K that is considered to represent approximately the temperature dependence of the resistivity without spin scattering of the conduction electrons.     

Excimer fluorescence in β-9,10-dichloroanthracene crystals

The fluorescence of single crystals of β-9,10-dichloroanthracene at 4.2 K consists solely of excimer emission (τ = 95 ± 5 ns). The absence of monomenc emission shows that excimer formation in this crystal is not a thermally activated process. This result is confirmed by excimer-excimer annihilation studies (γ(4.2 K) = 6 × 10⁻¹³, γ(298K) = 3 × 10⁻¹² cm³ s⁻¹).     

Mössbauer effect of FeOCl-pyridine complex

A Mössbauer effect study has been conducted on FeOCl-pyridine complex in the temperature range between 4.2° and 298°K. The isomer shift relative to Fe metal and the quadrupole splitting at 298°K are 0.36 ± 0.01 and 0.92 ± 0.01 mm/sec, respectively. An antiferromagnetic ordering occurs at 65 ± 3°K. The internal magnetic field is 435 ± 10 kOe at 4.2°K. The z axis of the electric field gradient tensor (|V_zz|> |V_xx| ? |V_yy|, η being small) is shown to be parallel to the direction of the internal magnetic field and perpendicular to the crystalline b axis.     

Ba2[Ni3N2]: a low-valent nitridonickelate-synthesis, crystal structure, and physical properties

The ternary alkaline-earth nitridonickelate Ba2[Ni3N2] (Ba2[NiI2Ni0N2]) was prepared by the reaction of mixtures of Ba2N and Ni in nitrogen gas of ambient back-pressure at 1173 K. The crystal structure determined by X-ray single-crystal and powder diffraction methods as well as from neutron diffraction data at various temperatures between 2 and 298 K is orthorhombic (Cmca (no. 64), 298 K: a=715.27(18) pm, b=1032.99(21) pm, c=740.12(20) pm) and provides the first example of a nitridonickelate with a two-dimensional complex anion. The Ni2 atom is described with a split position and the corresponding superstructure variants are investigated by theoretical full-potential nonorthogonal local-orbital calculations (FPLO). The average oxidation state of Ni in Ba2[Ni3N2] is +0.67, the lowest average value observed in nitridonickelates so far. Investigations of the physical properties demonstrate that Ba2[Ni3N2] acts as a "poor" metal with a large resistivity of approximately 2.7 mOmega cm at 300 K and exhibits low-dimensional magnetism with antiferromagnetic ordering at T approximately 90 K. XAS spectra correspond with low-valent Ni states.     

聚（对乙烯基苄基脲）大孔吸附树脂对银杏叶黄酮的吸附性能

通过静态吸附平衡和动态柱吸附试验,研究了自制大孔交联聚（对乙烯基苄基脲）树脂（简称PMVBU树脂）对银杏叶黄酮的吸附性能．结果表明,在pH=5．00时,该树脂对银杏叶黄酮有较好的吸附性能;PMVBU树脂对黄酮的吸附等温线符合Langmuir吸附等温方程,相关系数R^2〉0．99．308K时,PMVBU干树脂对黄酮的静态饱和吸附量达293．3mg／g．298K时,干树脂的动态吸附穿透容量为180mg／g．用75％的乙醇溶液对吸附在PMVBU树脂上的黄酮可进行有效洗脱．银杏叶提取液经过该树脂吸附柱吸附纯化后,黄酮纯度提高了18．6％,且树脂具有良好的重复使用性．     

Magnetic measurements on stable Fe(0) microclusters. Part 2

Zero valent iron microclusters were stabilized inside the pore structure ofA-type zeolites. The cage diameter of the matrix was 1.1 nm. Mößbauer spectra show superparamagnetic behaviour down to at least 77 K. Below 10 K, slow relaxation of most of the superparamagnetic moments was observed. Information on the magnetic properties was obtained from the Mößbauer spectra below 4.2 K and from measurements in an external magnetic field applied parallel to the gamma beam. Evidence has been found for both bulk-like and non-crystalline iron clusters.     

高铁酸钾的合成及其性能

高铁酸钾最初是作为选择性氧化剂或非氯型高效水处理剂使用。1999年lieht提出高铁酸钾作为电池的正极活性物质,对于高铁酸盐的认识达到一个新的高度。