Enhancing the oxygen permeability of BaCo(0.7)Fe(0.2)Nb(0.1)O(3-δ) membranes by coating GdBaCo(2-x)Fe(x)O(5+δ) for partial oxidation of coke oven gas to syngas

The dense ceramic membranes BaCo(0.7)Fe(0.2)Nb(0.1)O(3-δ) (BCFN) combined with GdBaCo(2-x)Fe(x)O(5+δ) (0 ≤ x ≤ 2.0) surface modification layers was investigated for hydrogen production by partial oxidation reforming of coke oven gas (COG). As oxygen permeation of BCFN membrane is controlled by the rate surface exchange kinetics, the GdBaCo(2-x)Fe(x)O(5+δ) materials improve the oxygen permeation flux of the BCFN membrane by 20-44% under helium atmosphere at 750 °C. The maximum oxygen permeation flux reached 14.4 mL min(-1) cm(-2) in the GdBaCoFeO(5+δ) coated BCFN membrane reactor at 850 °C, and a CH(4) conversion of 94.9%, a H(2) selectivity of 88.9%, and a CO selectivity of 99.6% have been achieved. The GdBaCo(2-x)Fe(x)O(5+δ) coating materials possess uniform porous structure, fast oxygen desorption rate and good compatibility with the membrane, which showed a potential application for the surface modification of the membrane reactor.     

Positive holes in magnesium oxide. Correlation between magnetic, electric, and dielectric anomalies

Magnetic susceptibility measurements of high purity MgO single crystals (<50-wt. ppm transition metals) by means of a vibrating-sample magnetometer shows an anomaly at 800 K. At the same temperature the electric conductivity increases anomalously, the static dielectric constant epsilon increases from 9 to approximately 150, a pronounced positive surface charge appears, and Fe2+ in the MgO matrix oxidizes to Fe3+. The data are consistent with O2(2-) (peroxy) defects, representing self-trapped, spin-paired positive holes at Mg2+ vacancy sites. Diamagnetic at low temperatures, the holes start to decouple their spins > 600 K, probably forming at first V0 centers (two O- at an Mg2+ vacancy), then V- centers (single O- at an Mg2+ vacancy), and releasing mobile O- states. These O- represent itinerant charge carriers on acceptor levels near the O 2p-dominated valence band and conduct by O- /O2- valency fluctuations. The O- concentration is of the order of 8 X 10(19) cm-3.     

Degradation of C.I. Reactive Red 2 (RR2) using ozone-based systems: comparisons of decolorization efficiency and power consumption

This study investigated the decolorization efficiency of C.I. Reactive Red 2 (RR2) in O3, O3/H2O2, O3/Fe3+, O3/H2O2/Fe3+, UV/O3, UV/O3/Fe3+, UV/O3/H2O2 and UV/O3/H2O2/Fe3+ systems at various pHs. The effective energy consumption constants and the electrical energy per order of pollutant removal (EE/O) were also determined. The experimental results indicated that the energy efficiency was highest at [H2O2]0=1000mg/l and [Fe3+]0=25mg/l. Accordingly, the H2O2 and Fe3+ doses in the hybrid ozone- and UV/ozone-based systems were controlled at these values. This work suggests that the dominant reactant in O3, O3/Fe3+ and O3/H2O2 systems was O3 and that in the O3/H2O2/Fe3+ system was H2O2/Fe3+. The experimental results revealed that the combinations of Fe3+ or H2O2/Fe3+ with O3 at pH 4 and of H2O2 or H2O2/Fe3+ with UV/O3 at pH 4 or 7 yielded a higher decolorization rate than O3 and UV/O3, respectively. At pH 4, the EE/O results demonstrated that the UV/O3/H2O2/Fe3+ system reduced 85% of the energy consumption compared with the UV/O3 system. Moreover, the O3/H2O2/Fe3+ system reduced 62% of the energy consumption compared with the O3 system. At pH 7, the EE/O results revealed that the UV/O3/H2O2/Fe3+ system consumed half the energy of the UV/O3 system.     

掺铈多组分硅酸盐玻璃电子辐照着色研究

采用吸收光谱、电子顺磁共振谱和光致发光谱对掺Ce多组分硅酸盐玻璃K509在10 MeV电子辐照下的色心动力学进行了研究。结果表明, 电子辐照引起K509玻璃可见光透过率降低的色心类型为非桥氧空穴色心HC1和HC2。在剂量率一定的情况下, 色心浓度随总剂量的增大呈指数函数增大; 在总剂量一定的情况下, 色心浓度随剂量率增大呈指数函数减小。Ce³⁺荧光强度的变化表明辐照过程中Ce³⁺浓度与辐照总剂量负相关, 与辐照剂量率正相关, 验证了掺Ce玻璃耐辐照机理: Ce³⁺吸收辐照产生的空穴从而抑制空穴色心HC1和HC2的形成, 且不引入额外的可见光波段吸收。通过对Ce³⁺宽带荧光峰进行高斯拟合, 得到了K509中Ce³⁺能级结构图。     

Mesoporous nickel–iron binary oxide nanorods for efficient electrocatalytic water oxidation

The design and fabrication of low-cost,high-efficiency,and stable oxygen-evolving catalysts are essential for promoting the overall efficiency of water electrolysis.In this study,mesoporous Ni1-xFexOy (0 ≤ x ≤ 1,1 ≤ y ≤ 1.5) nanorods were synthesized by the facile thermal decomposition of Ni-Fe-based coordination polymers.These polymers passed their nanorod-like morphology to oxides,which served as active catalysts for oxygen evolution reaction (OER).Increasing the Fe-doping amount to 33 at.％ decreased the particle size and charge-transfer resistance and increased the surface area,resulting in a reduced overpotential (～302 mV) at 10 mA/cm2 and a reduced Tafel slope (～42 mV/dec),which were accompanied by a far improved OER activity compared with those of commercial RuO2 and IrO2 electrocatalysts.At Fe-doping concentrations higher than 33 at.％,the trend of the electrocatalytic parameters started to reverse.The shift in the dopant concentration of Fe was further reflected in the structural transformation from a NiO (＜33 at.％ Fe) rock-salt structure to a biphasic NiO/NiFe2O4 (33 at.％ Fe) heterostructure,a NiFe2O4 (66 at.％ Fe) spinel structure,and eventually to α-Fe2O3 (100 at.％ Fe).The efficient water-oxidation activity is ascribed to the highly mesoporous one-dimensional nanostructure,large surface area,and optimal amounts of the dopant Fe.The merits of abundance in the Earth,scalable synthesis,and highly efficient electrocatalytic activity make mesoporous Ni-Fe binary oxides promising oxygen-evolving catalysts for water splitting.     

γ辐照及热退火对光热折变玻璃光学性能的影响

对光热折变(Photo-thermal-refractive, PTR)玻璃在总剂量分别为0.35、1、10及100 kGy的γ射线下辐照,并进行热退火处理,采用吸收光谱、光致发光光谱及EPR电子顺磁共振谱研究了光热折变玻璃在γ射线辐照下的辐照机理。研究结果表明,γ辐照后的PTR玻璃在可见波段的吸收主要由银原子Ag⁰、银分子簇Ag₂、银分子簇Ag₃、银纳米颗粒Ag_m⁰及非桥氧空穴中心H_C1及HC₂引起;在不同剂量γ射线辐照下,玻璃基质中的变价离子(Ag⁺、Ce³⁺)价态先发生变化,同时玻璃基质中的非桥氧键发生电离,形成了非桥氧空穴型缺陷中心HC₁、HC₂。进一步增加辐照剂量,产生了银的分子簇Ag₂和Ag₃;同时玻璃基质中非桥氧空穴中心HC₂的浓度增大,导致在639 nm附近的吸收增强...     

掺杂(Fe、Nb)SrTiO3晶界组成的电子能量损失谱(EELS)分析

采用高空间分辨率扫描透射电镜（STEM）对掺杂（Fe^3 、Nb^5 ）SrTiO3晶界进行了观察，并利用采集的电子能量损失谱（EELS）对晶界组成进行了分析，结果表明，掺杂Fe的SrTiO3陶瓷晶界存在1nm左右的非晶膜，同晶体内部相比晶界缺Sr；三叉晶界为钛基玻璃相，Ti、O及Fe含量明显高于晶界，掺Nb的SrTiO3陶瓷晶界同晶粒相比同样缺Sr，三叉晶界主要以SiO2非晶相为主，Fe^3 、Nb^5 对Ti^4 的替位及在晶界的偏析引起SrTiO3晶格畸变是导致晶界组成变化的主要原因。     

Green synthesis of uniform magnetite (Fe3O4) nanoparticles and micron cubes

Single-crystalline Fe3O4 microcubes were obtained through a green hydrothermal procedure using Fe3+, Fe2+ and H2O2 as starting materials. The structures and morphologies of the as-prepared samples were characterized in detail by X-ray diffraction (XRD), Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) respectively. Magnetite (Fe3O4) cubes averaging 3 microm in diameter were synthesized by H2O2 oxidation of Fe3+ and Fe2+ under neutral conditions. The contrastive experiments were designed to elucidate the effects of Fe3+, Fe2+ and H2O2 on the morphology of the final products. Irregular and ellipsoidal Fe2O3 structures were obtained by H2O2 oxidation of Fe3+ and Fe2+ respectively. Meanwhile, Fe3O4 nanotubes and nanoparticles were obtained when H2O2 was replaced by NH4HCO3 and urea respectively. The results show that H2O2, Fe3+ and Fe2+ in the reactive system play critical roles in obtaining micrometric cube-like Fe3O4. While, other nanometric Fe2O3 and Fe3O4 particles with tube-like and other morphologies could also be developed by controlling the reaction parameters.     

Novel active heterogeneous Fenton system based on Fe3-xMxO4 (Fe, Co, Mn, Ni): the role of M2+ species on the reactivity towards H2O2 reactions

In this work, the effect of incorporation of M2+ species, i.e. Co2+, Mn2+ and Ni2+, into the magnetite structure to increase the reactivity towards H2O2 reactions was investigated. The following magnetites Fe3-xMnxO4, Fe3-xCoxO4 and Fe3-xNixO4 and the iron oxides Fe3O4, gamma-Fe2O3 and alpha-Fe2O3 were prepared and characterized by M?ssbauer spectroscopy, XRD, BET surface area, magnetization and chemical analyses. The obtained results showed that the M2+ species at the octahedral site in the magnetite strongly affects the reactivity towards H2O2, i.e. (i) the peroxide decomposition to O2 and (ii) the oxidation of organic molecules, such as the dye methylene blue and chlorobenzene in aqueous medium. Experiments with maghemite, gamma-Fe2O3 and hematite, alpha-Fe2O3, showed very low activities compared to Fe3O4, suggesting that the presence of Fe2+ in the oxide plays an important role for the activation of H2O2. The presence of Co or Mn in the magnetite structure produced a remarkable increase in the reactivity, whereas Ni inhibited the H2O2 reactions. The obtained results suggest a surface initiated reaction involving Msurf2+ (Fe, Co or Mn), producing HO radicals, which can lead to two competitive reactions, i.e. the decomposition of H2O2 or the oxidation of organics present in the aqueous medium. The unique effect of Co and Mn is discussed in terms of the thermodynamically favorable Cosurf3+ and Mnsurf3+ reduction by Femagnetite2+ regenerating the active species M2+.     

P2O3-B2O3-Al2O3-SrO-BaO玻璃中Yb3+非辐射能量转移下Er3+离子的增强发射

本文研究了共掺Er3 +/Yb3 +P2 O3 -B2 O3 -Al2 O3 -SrO -BaO玻璃的能量转移过程。实验中制备了高掺杂Yb3 +离子的双掺Er3 +/Yb3 +的磷酸盐玻璃样品。在Er3 +/Yb3 +掺杂比率 >1 :1 8(mol% )时 ,观测到了基于Yb3 +离子至Er3 +离子能量转移下Er3 +( 4 I13 / 2 →4I15 / 2 )的增强发射和Yb3 +( 2 F7/ 2 →2 F5 / 2 )发射的减弱 ,当Yb3 +离子掺杂浓度超过 2 .1× 1 0 2 1ions/cm3 时 (Er3 +/Yb3 +≤ 1 :1 8,mol% ) ,由于Yb3 +离子的自淬灭效应 ,Er3 +离子的发射强度降低。实验中得到了Yb3 +离子的最佳掺杂浓度为1 .74× 1 0 2 1ions/cm3     

双微乳液法制备掺杂Fe~(3+)的纳米TiO_2及其光催化性能

为了研究双微乳液法在制备纳米级光催化剂的应用,以TiCl4和NH3.H2O为原料,采用十六烷基三甲基溴化铵-正丁醇-环己烷-水微乳体系制备Fe3+掺杂纳米TiO2,对粉末的晶体结构进行X射线衍射表征,并以其对p-甲酚的降解考察其光催化活性。结果表明,在较小的掺杂量时,Fe3+掺杂量的提高可以提高TiO2的光催化活性,进一步提高掺杂量将引起光催化活性的降低;掺杂Fe3+可导致纳米TiO2的粒径减小;Fe3+的半径较小以及Fe2O3的熔点较低均有利于TiO2从锐钛矿向金红石的相变;当Fe3+掺杂摩尔分数为0.06%,煅烧温度为550℃时,纳米TiO2的光催化活性最高,此时形成TiO2的锐钛矿和金红石相的混晶;乳液中含水量也会影响晶相的组成和粒径大小,随着含水量增加产物中出现了一定比例的金红石相。     

EPR of Irradiation Induced Centers in Some VitreousMatrices Containing Copper

Boro-germanate glasses containing copper, i.e., xCuO(1-x)[GeO2·B2O3] subjected to gamma irradiation, were studied by means of EPR. Comparisons were made with the xCuO·(1-x)[Na2B4O7] system. Irradiation induced centers were detected. These are: electron trapped at a hydrogen compensated germanium ion centers; boron oxygen hole centers and electron trapped at an oxygen vacancy centers. Strong dependence of the paramagnetic irradiation-induced centers concentration on the CuO content of the sample was evidenced.     

Electrical properties of semiconductor CdS studied by adsorption spectroscopy

The electrical conductivity of semiconductor CdS films (d ≤ 1 μm) having (0001)S and (0001)Cd polar faces has been measured as a function of temperature at different degrees of adsorption of O₂, NO₂, and N₂O molecules. Adsorption spectroscopy has been used to identify bulk and surface electronic centers in a series of states with a wide range of ionization energies: E _t = 0.14–2.21 eV. In contrast to the bulk centers, which have a quasi-continuous energy spectrum characteristic of CdS, the surface adsorption electronic centers have a discrete energy spectrum. The ionization energy of the electronic centers of adsorption origin in CdS + O₂, CdS + NO₂, and CdS + N₂O structures has been measured for the first time at both polarities of the CdS faces and has been shown to depend on the chemistry of the adsorbate and the polarity of the film face.     

Spectroelectrochemical sensing based on multimode selectivity simultaneously achievable in a single device. 20. Detection of metal ions in different oxidation states

Spectroelectrochemical sensing a metal in two different oxidation states, both of which are weakly absorbing in the visible wavelength range, was demonstrated with ferrous and ferric ion. The sensor consisted of an indium tin oxide optically transparent electrode (ITO OTE) coated with a thin film of Nafion preloaded with the ligand 2,2'-bipyridine (bipy). Fe2+ in the sample partitioned into the film where it reacted with bipy to form Fe(bipy)3(2+), which absorbs strongly at 520 nm. The change in absorbance (DeltaA) at 520 nm associated with the accumulation of Fe(bipy)3(2+) complex in the film was measured by attenuated total reflectance spectroscopy and was proportional to the concentration of Fe2+ in the sample. Iron in the Fe3+ form can also be determined, but it has a more complex coordination chemistry involving formation of [Fe2(bipy)4O(H2O)2]4+ as well as Fe(bipy)3(3+) in the film. Fe3+ was detected indirectly by reducing the nonabsorbing Fe3+-bipy complexes that accumulated in the film to absorbing Fe(bipy)3(2+) and monitoring DeltaA at 520 nm. The effects of film thickness and ligand concentration in the film on sensor sensitivity and response time for Fe2+ were evaluated. Detection limits of 0.6 x 10(-6) M for Fe2+ and 2 x 10(-6) M for Fe3+ were obtained with 300 nm thick films after 30 min of exposure to a quiescent sample. Careful manipulation of the potential applied with simultaneous optical detection enables Fe2+ to be distinguished from Fe3+, which is the first step in developing a sensor for speciating the two oxidation states in a mixture.     

Decolourization of Methyl Orange using Fenton-like mesoporous Fe(2)O(3)-SiO(2) composite

Rapid decolourization of Methyl Orange by Fenton-like mesoporous Fe(2)O(3)-SiO(2) catalyst has been reported. The effect of various parameters such as initial pH, initial H(2)O(2) concentration, Fe content in the catalyst and initial dye concentration on decolourization process were studied. The results show that 20mg of mesoporous Fe(2)O(3)/SiO(2) composite (with Si/Fe=10) was sufficient to decolourize 0.6 mg/ml of Methyl Orange in presence of 2 ml of H(2)O(2) at an initial pH of 2.93 within 20 min. The pH range for effective decolourization (≥90%) was found to be 1-3. Leaching tests indicated that the activity of the catalyst was almost unaffected up to three consecutive cycles although ≤0.2 ppm of Fe ion was leached into treated water in each run.     

Crystallization of a Bi–Pb–Fe–Cd–O glass under magnetic annealing

Magnetic annealing with a tunable solenoid magnetic field from 0–240 G, was conducted on a Bi–Pb–Fe–Cd–O glass containing 20% Fe2O3, which was prepared by the melt-quenching process. The crystalline phases of the annealed samples were identified as -Bi2O3 and BiFeO3. Evidence of the formation of the crystalline BiFeO3 which was strongly magnetically enhanced at the surface of the samples, was obtained from X-ray diffraction patterns and EPR spectra. Based on the structure transition of Fe3+ ions, a crystallization mechanism for the BiFeO3 crystals under magnetic annealing has been proposed.     

氧化铁粉末化学组成对合成SHS复合弯管内衬陶瓷的影响

基于重力分离SHS法制备陶瓷内衬复合弯管 ,研究了氧化铁粉末化学组成对SHS复合弯管内衬陶瓷的影响 .研究发现在铝热剂相同质量分数条件下 ,存在于工业原料Fe2 O3 粉末的杂质比SiO2 添加剂对燃烧过程的稀释效应更为强烈 .在工业原料Fe2 O3 +Al体系中加入适量的Fe3 O4+Al体系 ,使燃烧温度、蔓延速率及SHS反应转化率均有所升高 ;但加入过量的Fe3 O4+Al体系 ,虽然使蔓延速率进一步增大 ,但却引起燃烧温度和SHS反应转化率有所下降 .实验表明 ,在工业原料Fe2 O3 +Al体系中加入 1 5 %的Fe3 O4+Al体系 ,使复合弯管内衬陶瓷性能达到并超过用分析纯Fe2 O3+Al体系所制备的复合弯管内衬陶瓷性能 .     

CaO-Al2O3-SiO2系黑色装饰微晶玻璃的研究

为了研究制备黑色装饰微晶玻璃,使用Fe2O3、Ni2O3、Co2O3等着色剂,研究了其对微晶玻璃装饰板材的颜色、烧结和晶化性能的影响规律,确定合理的着色剂种类、含量以及热处理制度,并利用XRD与SEM等技术研究了黑色装饰微晶玻璃的结构.研究表明:以Fe2O3、Co2O3组合和Fe2O3、Co2O3、Ni2O3的组合都可制得黑色系列玻璃与花纹清晰的黑色微晶玻璃;100g玻璃配合料中,较合理的着色剂用量为:Fe2O33～5g,Co2O30.15～0.25 g,Ni2O30.2～0.4 g.     

Kinetics modeling in photosensitive glass

Kinetics of photoinduced process is studied in a new photosensitive material for volume hologram recording which is a photo-thermo-refractive glass (PTRG). A system of balance equations is derived which describes the processes of generation of electrons in a conduction band of these glass matrix by photoionization of Ce³⁺ and trapping of electrons by both silver ions Ag⁺ and hole centers (Ce³⁺)⁺. The main approach for the system solution is a calculation of low quasistationary concentration of free electrons in a conduction band, while concentrations of generated electron and hole centers are expected to be variable. A general solution of a system is found as a combination of exponential and hyperbolic functions. It is shown that an exponential solution is the result of the absence of a re-trapping of electrons, while a pure hyperbolic solution occurs in the case of equal probability of trapping and re-trapping. The approach developed for the first stage of photo-thermo-refractive process which is photoionization and trapping, is applied for the modeling of the final result of the whole process of photo-thermo-induced refractive index transformation in glass. It is found that the refractive index increment in PTRG is better described by hyperbolic function compare to the exponential one. Kinetic parameters of induced refraction in PTRG are determined.     

Soluble phosphate glass fibres for repair of bone-ligament interface

Phosphate-based fibres of the generic composition (CaO)0.46-(Na2O)n-(Fe2O3)y-(P2O5)0.50 have been evaluated, in vitro, as three dimensional scaffolds for tissue engineering of the hard-soft tissue interface by assessing the fibre solubility and growth and functional gene expression of human cells. Primary human osteoblasts and fibroblasts were seeded onto scaffolds and maintained in culture for up to 21 days. Fluorescent immunolabeling revealed the spread cell morphology and significant proliferation pattern on these fibres, particularly on the 3 mol% Fe2O3-containing formulation. Real-time quantitative Polymerase Chain Reaction (rtQ-PCR) analysis of gene expression using TaqMan Probes was preformed and it has been established that committed cell differentiation was maintained by both cell types, and was strongly related to the 3 mol% Fe2O3 glass composition. These novel, readily manufactured, soluble glass fibres offer a biocompatible and biochemically favourable alternative in the search for suitable degradable materials used in Tissue Engineering.