Fe_4^(3+)FeTiO_9,一个由2Fe_2O_3-FeTiO_3组成的铁-钛氧化物矿物

Fe－Ti氧化物矿物产于新疆阿尔泰伟晶岩中．与之共生的有铌-钽铁矿、细晶石、锆石、白云母、长石等。Fe－Ti氧化物是不规则粒状，黑褐色．条痕浅褐红色．金属光泽，无解理，硬度5．5～6．0．比重5.30～5．50。在反光镜下矿物的反射色为灰白色，反射多色性弱，在MPV－3型裂隙光度计上其反射率为27．37～22．65（400～700nm）。化学分析结果是：Fe2O362．23，MgO0．22．Mno1．24．FeO13．98，TiO217．96，SiO23．87，CaO0．20，总计9970．扣除杂质后：Fe2O364．87，MgO0．24．MnO1．29．FeO14．58．TiO218．73，总计99．70，其化学式为FeFeTiO9。矿物的强X射线值：2．72（10，014）．2．52（10．110）．1．85（8．115），1．70（9，008）．1．457（8，027），三方晶系a=0．504，c=1．355nm．Z=2．空间群P63／m（？）。

γ-Fe_2O_3纳米粉的低热固相制备及其电磁损耗特性(英文)

The Fe(OH) 3 precursor was prepared by solid-state reaction with Fe(NO 3 ) 3 ·9H 2 O,NaOH and dispersed poly-ethylene glycol at low heating temperature(25℃).Synthesis of iron oxide(γ-Fe 2 O 3 )nanoparticle was achieved by thermal decomposition of Fe(OH) 3 ·xH 2 O precursor.The nanoparticle was characterized by TG-DTA,X-ray diffra-ction,TEM etc.The results showed that the nanoparticle was composed ofγ-Fe 2 O 3 and was a better absorber for electromagnetic wave within the low frequency band.

Influence of Microwave Radiation on Properties and Structure of Fe_2O_3/SO_4^(2-) Solid Superacid Catalyst

The microwave radiation method was introduced to prepare the Fe_2O_3/SO solid superacid.Its structure and properties were investigated by means of X-ray diffraction and infrared spectrum analyses as well as measurement of magnetic susceptibility and rate of esterification. The structure of the superacids prepared in microwave field can be crystalline or non-crystalline, the latter has not been reported yet in literatures. Comparing with the traditional superacid, the non-crystalline Fe2O3/SO superacid prepared in microwave field has the highest magnetic susceptibility and catalytic activity. The di-coordination of Fe2O3 and SO and the S=O bi-bond were reinforced by microwave radiation, which is favorable for increasing the acid intensity of the Fe2O3/SO catalyst

Co_(3)O_(4)/CeO_(2)催化剂上丙烷完全氧化反应中载体性质影响

采用不同制备方法合成不同性质的CeO_(2)载体,并制备负载型Co_(3)O_(4)/CeO_(2)催化剂应用于丙烷完全氧化反应。结果表明,部分CO_(2)+进入CeO_(2)晶格中形成固溶体,改变了CeO_(2)的晶格结构并产生氧空位。氧空位的数量与不同性质的CeO_(2)密切相关,影响催化剂上氧物种的可还原性,从而对反应行为产生影响。其中,以沉淀法制备的CeO_(2)为载体的5Co/CeO_(2)-C催化剂活性最佳(T_(90)=320℃),可归因于该催化剂中较高氧空位浓度导致的最佳低温可还原性。此外,该催化剂还具有良好的稳定性和抗水性能。

水热改性制备固体酸S_2O_8^(2-)/Fe_2O_3-SiO_2及其催化性能的初步探讨

采用共沉淀法制备Fe2O3-SiO2 混合氧化物前驱体 ,并对其进行水热改性处理 ,经浸渍(NH4)2S2O8 溶液后再焙烧得S2O82 -/Fe2O3-SiO2 固体酸催化剂。研究了制备条件对催化活性的影响 ,用乙酸/丁醇酯化反应评估该固体酸的催化性能。实验结果显示 ,最佳工艺条件为,n(Fe):n(Si)=1:4 ,150℃水压热处理1h ,在0.5mol·L-1 的(NH4)2S2O8 溶液中浸渍6h ,500℃焙烧3h ,在此条件下乙酸的转化率可达94.11 %。

Oxidation of Mercaptans from Light Oil Sweetening by Fe_2O_3/MgO/Al_2O_3 Supported CoPcS Catalyst

MgO/Al2O3 and Fe2O3/MgO/Al2O3 solid bases were prepared through mixing method. After sulfonated cobalt phthalocyanine （CoPcS） being supported on these solid bases, the catalytic performance of these catalysts was evaluated by means of mercaptan oxidation reaction. The samples were characterized by X-ray diffraction （XRD）, CO2 temperature-programmed desorption （CO2-TPD）, FTIR spectroscopy, and X-ray photoelectron spectroscopy （XPS）. Investigation was focused on the effect of Fe2O3 on activity, crystal structure, basicity, and stability of the catalyst and also on the role of Fe2O3 in the mercaptan oxidation processes. Test results have shown that the Fe2O3/MgO/Al2O3- CoPcS catalyst has a higher initial activity and a much longer service life than the MgO/Al2O3-CoPcS catalyst. The increased types of basic sites coupled with an enhanced oxidation ability resulted from the addition of Fe2O3 have contributed to the improvement of the catalytic activity of the MgO/Al2O3-CoPcS catalyst.

Cathodic electrophoretic deposition of α-Fe_2O_3 coating

Submicro α-Fe2O3 coatings were formed using electrophoretic deposition(EPD) technique in aqueous media. The zeta potentials of different α-Fe2O3 suspensions with different additives were measured as a function of p H to identify the optimum suspension condition for deposition. Electrophoretic depositions of α-Fe2O3 coatings under different applied electric fields and deposition time were studied and the effects of applied voltages and deposition time on deposition rates and thicknesses were investigated. The particle packing densities of the deposits at various applied voltages and deposition time were also analyzed by a scanning electron microscope(SEM). The results show that crack-free α-Fe2O3 coatings with uniform microstructure and good adherence to the nickel substrates are successfully obtained. Electrophoretic deposited α-Fe2O3 coating from aqueous suspension is a feasible, low-cost and environmental friendly method.

Al_2O_3-SiC系制品中添加物α-Cr_2O_3的行为

以电熔刚玉和SiC为基料的制品中添加适量亚微米级的绿铬 (α Cr2 O3)时 ,烧成过程中α Cr2 O3生长到 1～ 5μm ,并与刚玉表面接触区发生互扩散行为。SiC在氧化层中氧化并形成玻璃纤维 ,使氧化层的组分变为Al2 O3-Cr2 O3-SiO2 系。所形成的高硅质液相能促进 (Al2 -x,Crx)O3固溶体析晶 ,晶体呈较大的六方柱状自形晶 ,长度达 5～ 2 0 μm ,长径比 ( )为 5～ 1 0。但此液相中不含Cr2 O3。

弛豫铁电体Pb(B_1B_2)O_3和钛酸铅固溶体的相稳定性

弛豫铁电体Pb(B1B2 )O3 和PbTiO3 能够形成具有复合钙钛矿结构的二元固溶体Pb(B1B2 )O3 PbTiO3 。到目前为止 ,已经发现了多种这类二元固溶体单晶 (如PMN PT、PZN PT和PSN PT等 )不仅具有良好的介电性能 ,而且具有良好的压电性能。和普通压电陶瓷PZT相比较 ,弛豫铁电单晶的纵向机电耦合系数k3 3 要大得多 ,可以达到 90 %以上。由于缺少这类二元固溶体单晶的高温相图 ,这类单晶的生长比较困难。我们通过对几种具有复合钙钛矿结构的二元固溶体体系 ,进行差热分析 (DTA)和热重分析 (TG) ,分析了固溶体的相关系和相稳定性。并用粉末X射线衍射谱 (XRD)分析了固溶体的结构 ,以便确定相应的单晶生长方法。研究结果表明 ,A(B1B2 )O3 PbTiO3 二元固溶体体系的结果比较复杂 ,体系中除了具有钙钛结构的铁电相之外 ,还有多种焦绿石相 ,而且不同的弛豫铁电体形成的固溶体其相稳定性的差异较大。其中PMN PT固溶体的相稳定性较高。研究结果表明 ,PMN PT固溶体的液相线和固相线比较接近 ,晶体生长中的分凝现象较小 ,可以看作为同成分熔化的化合物 ,故可以用熔体法来直接生长单晶。PZN PT单晶的相稳定性较差 ,需要加入一定量的溶剂才能使相稳定 ,故可以用助熔剂法来生长PZN PT单晶。

Pressureless infiltration of Si_3N_4 preforms with an Al-2wt%Mg alloy

The pressureless infiltration process to synthesize a silicon nitride composite was investigated. An Al-2wt%Mg alloy was infiltrated into silicon nitride preforms in the atmosphere of nitrogen. It is possible to infiltrate the Al-2wt%Mg alloy in silicon nitride preforms, The growth of the composite with useful thickness was facilitated by the presence of magnesium powder at the interface and by flowing nitrogen. The microstructure of the Si3N4-Al composite has been characterized using scanning electron microscope. During the infiltration of Si3N4 preforms, Si3N4 reacted with aluminium to form silicon and AIN. The silicon produced during the growth consumed in the formation of MgSiAIO, MgSiAlN and Al3.27Si0.47 type phases. The growth of the composite was found to proceed in two ways, depending on the oxide content in the initial preforms, First, less oxide content preforms gave rise to MgAlSiO and MgAlSiN type phases after infiltration. Second, more oxide content preforms gave rise to AlN-Al2O3 solid solution phase （AlON）, The AlON phase was only present in the composite, containing 10% aluminium in the silicon nitride preforms before infiltration.

Effect of SO_2 on Performance of Solid Oxide Fuel Cell Cathodes

Effects of SO2 in ambient air on the performance and durability of solid oxide fuel cell（SOFC） cathode were evaluated by galvanostatic measurement. Comparison between two cathode materials was made to consider the cathode degradation mechanisms. The degradation performance is associated with a slow decomposition of the La0.6Sr0.4Co0.2Fe0.8O3（LSCF） due to the segregation of strontium oxide. Negligible deterioration for （La0.7Sr0.3）MnO3 （LSM） cathode was caused by SO2 poisoning under a current density of 200 mA/cm2. Metal sulphate formation may explain a slight deterioration under increasing high the concentration of SO2. It was verified that the poisoning mechanism for the two cathode materials resulted from the gradual decomposition of the cathode materials.

Reaction behavior of kaolinite with ferric oxide during reduction roasting

The pre-separation of silica and alumina in aluminosilicates is of great significance for efficiently treating alumina-/ silica-bearing minerals for alumina production. In this work, the reaction behavior of kaolinite with ferric oxide during reduction roasting was investigated. The results of thermodynamic analyses and reduction roasting experiments show that ferrous oxide obtained from ferric oxide reduction preferentially reacts with alumina in kaolinite to form hercynite, meanwhile the silica in kaolinite is transformed into quartz solid solution and/or cristobalite solid solution. With increasing roasting temperature, fayalite formed by reaction of surplus ferrous oxide with silica at low temperature is reduced to silica and metallic iron in the presence of sufficient carbon dosage. However, increasing roasting temperature and decreasing Fe2O3/Al2O3 molar ratio favor mullite formation. The complete conversion of kaolinte into free silica and hercynite can be obtained by roasting raw meal of kaolin, ferric oxide and coal powder with Fe2O3/Al2O3/C molar ratio of 1.2:2.0:1.2 at 1373 K for 60 min. This work may facilitate the development of a technique for comprehensively utilizing silica and alumina in aluminosilicates.

Distribution of P2O5 between solid solution and liquid phase in dephosphorization slag of CaO-SiO2-FeO-P2O5-Na2O system

A multi-phase slag containing Na2O is potential to efficiently dephosphorize high-P hot metal.After dephosphorization,the generated slag with high P2O5 content is regarded as a P resource.Because P2O5 was mainly concentrated in the 2CaO SiO2-3CaO P2O5 solid solution,the recovery of P from dephosphorization slag primarily depends on the separation of the solid solution from other phases.The distribution ratios of P2O5 between solid solution and liquid phase in the CaOSiO2-FeO-P2O5-Nslag system were investigated.The results indicated that the addition of Na2O facilitated the enrichment of P2O5 in the solid solution because it increased not only the distribution ratio of P2O5 but also the mass fraction of the solid solution.The distribution ratio of P2O5 was independent of the P2O5 content in slag.A higher P2O5 content in slag resulted in higher P2O5 and Na2O contents in the solid solution.The distribution ratio of P2O5 increased with the total Fe content in the liquid phase,regardless of the valence of Fe.An increase in the FeO content in slag brought a higher P2O5 content in the solid solution.As slag basicity increased,the distribution ratio of P2O5 increased,but the P2O5 content in the solid solution decreased.

Selective oxidation of methane and carbon deposition over Fe_2O_3/Ce_(1-x)Zr_xO_2 oxides

A series of Fe2O3/Al2O3, Fe2O3/CeO2, Ce0.7Zr0.3O2, and Fe2O3/Ce1-xZrxO2（x = 0.1–0.4） oxides was prepared and their physicochemical features were investigated by X-ray diffraction（XRD）, transmission electron microscope（TEM）, and H2-temperature-programmed reduction（H2-TPR） techniques. The gas–solid reactions between these oxides and methane for syngas generation as well as the catalytic performance for selective oxidation of carbon deposition in O2-enriched atmosphere were investigated in detail. The results show that the samples with the presence of Fe2O3show much higher activity for methane oxidation compared with the Ce0.7Zr0.3O2solid solution,while the CeO2-contained samples represent higher CO selectively in methane oxidation than the Fe2O3/Al2O3sample. This suggests that the iron species should be the active sites for methane activation, and the cerium oxides provide the oxygen source for the selective oxidation of the activated methane to syngas during the reaction between methane and Fe2O3/Ce0.7Zr0.3O2. For the oxidation process of the carbon deposition, the CeO2-containing samples show much higher CO selectivity than the Fe2O3/Al2O3sample, which indicates that the cerium species should play a very important role in catalyzing the carbon selective oxidation to CO. The presence of the Ce–Zr–O solid solution could induce the growth direction of the carbonfilament, resulting in a loose contact between the carbon filament and the catalyst. This results in abundant exposed active sites for catalyzing carbon oxidation, strongly improving the oxidation rate of the carbon deposition over this sample. In addition, the Fe2O3/Ce0.7Zr0.3O2also represents much higher selectivity（ca. 97 %） for the conversion of carbon to CO than the Fe2O3/CeO2sample, which can be attributed to the higher concentration of reduced cerium sites on this sample. The increase of the Zr content in the Fe2O3/Ce1-xZrxO2samples could improve the reactivity of the materials for methane oxidation, but it also reduces the selectivity for CO formation.

MgO含量对微晶玻璃结构及性能的影响

锂铝硅系微晶玻璃是一种具有优异的光学、力学性能的微晶玻璃材料。本文制备了以透锂长石和二硅酸锂为主晶相的锂铝硅系透明微晶玻璃,并通过DSC、XRD与SEM研究了MgO含量对该微晶玻璃析晶行为及结构的影响,利用维氏硬度、抗弯强度等测试方法研究了MgO含量对该微晶玻璃力学性能的影响。结果表明,当MgO含量(质量分数)从0%增加至3%,基础玻璃的析晶温度从771℃降低至729℃,析晶能力增强,微晶玻璃的结晶度从62%增加至72%,晶粒尺寸从29 nm增大至33 nm。随着MgO含量的增加,微晶玻璃中会析出β-石英固溶体,抗弯强度增大。

Structures and oxygen storage capacities of CeO_2-ZrO_2-Al_2O_3 ternary oxides prepared by a green route:supercritical anti-solvent precipitation

CeO2-ZrO2-Al2O3 ternary oxides were successfully prepared by a green route of supercritical anti-solvent precipitation with supercritical CO2 as anti-solvent and methanol as solvent. The structures and oxygen storage capacities of these ternary oxides were characterized by XRD, Raman spectra and oxygen storage capacity measurements. It was found that Al3＋ and Zr4＋ inserted into CeO2 lattice, forming CeO2-ZrO2-Al2O3 solid solution. The concentration of aluminium isopropoxide in the solution affected the concentration of oxygen vacancy and the distortion of oxygen sublattice which were responsible for the oxygen storage capacity. The rapidest oxygen uptake/release rate and maximum total oxygen storage capacity （122.0 mmolO2/molCeO2） were obtained with the aluminitun isopropoxide concentration at 0.2 wt.% in the solution.

MnO_x/Ce_(0.5+x)Zr_(0.4–x)La_(0.1)O_(1.95)-Al_2O_3 catalysts used for benzene catalytic combustion

Complete oxidation of benzene over supported manganese oxides catalysts was studied.Composite supports Ce0.5＋xZr0.4–xLa0.1O1.95-Al2O3 （x=0,0.1,0.2,0.3,0.4）,and CeO2-Al2O3 were prepared by co-precipitation method,and manganese oxides （MnOx） catalysts were prepared by incipient wetness method.Catalytic activity was performed in a conventional fixed bed flow reactor.Among these catalysts,MnOx supported on Ce0.8Zr0.1La0.1O1.95-Al2O3 was found to have the highest catalytic activity for benzene oxidation.The complete conversion temperature of benzene on MnOx/Ce0.8Zr0.1La0.1O1.95-Al2O3 was 328 oC.The catalysts were characterized by X-ray diffraction （XRD）,Brunauer-Emmett-Teller （BET） specific surface area,X-ray photoelectron spectra （XPS） and H2-temperature programmed reduction （H2-TPR）.The results of BET and XRD measurements indicated that the addition of ZrO2 improved the textural properties.XPS measurements showed that MnOx was composed of MnO2 and Mn2O3.The catalysts reported in this work have significant potential in industrial application for their high performance and low cost.

Relationship between powder characteristic and internal oxidation of Al in Cu-Al pre-alloyed powders

Since Cu-Al powder characteristics have important effects on the preparation of Cu/Al2O3 composite, the apparent activation energy of Al internal oxidation reaction in Cu-Al pre-alloyed powders with different characteristics was calculated in the present investigation. The microstructure and properties of the synthesized Cu/Al2O3 were studied. The results show that high-energy milling can obviously promote internal oxidation of Al in Cu-Al powders in the same solid solubility. At the same milling conditions and internal oxidation parameters, the solid solution of Al in Cu either in low or high amount will result in the poor microstructure and properties of the Cu/Al2O3 composite. Subsequently, when high-energy milling and internal oxidation are synchronously used to prepare the Cu/Al2O3 composite, there should be an appropriate solubility and milling effect for the pre-alloyed powders.

超低膨胀微晶玻璃发展现状及应用

超低膨胀微晶玻璃是在Li_(2)O-Al_(2)O_(3)-SiO_(2)系玻璃的基础上经过严格的受控晶化,在母体玻璃中析出以β-石英固溶体为主晶相的微晶玻璃材料。由于具有极低的热膨胀系数,以及优异的热稳定性、化学稳定性和力学性能,超低膨胀微晶玻璃在诸多领域得到了广泛应用。本文综述了超低膨胀微晶玻璃的组成、制备方法、国内外研究历程及发展现状、应用,指出了目前生产超低膨胀微晶玻璃存在的问题和国产超低膨胀微晶玻璃与国际顶尖产品存在的差距,以及国产超低膨胀微晶玻璃今后的发展方向。

预氧化对钛铁矿结构及其产物金红石的影响

利用X射线衍射分析和流态化酸解水解工艺,研究预氧化温度和时间对钛铁矿晶体结构及其产物金红石的影响。结果表明,预氧化温度低于800℃时,生成了金红石微晶和FeTiO3·Fe2O3固溶体,预氧化温度高于850℃时,生成了明显的金红石相和铁板钛矿Fe2O3·TiO2,原来的钛铁矿结构被破坏。产物金红石TiO2纯度随着预氧化温度的升高先增加后减少,预氧化温度为800℃时,TiO2纯度最高,为90.03%。预氧化时间从15 min增加到60 min,逐渐生成金红石微晶和FeTiO3·Fe2O3固溶体,没有破坏原来钛铁矿的结构,预氧化时间对产物金红石的TiO2纯度影响较小。