Physicochemical Properties of Nanocrystallite Copper Ferrite Prepared by a Novel Self Flash Combustion of Acetate Precursors

Copper ferrite, CuFe2O4, one of the important ferrites due to its interesting electrical, magnetic and structural properties, is obtained by a novel self flash combustion of a homogeneous mixture of one mole copper acetate monohydrate, Cu（CH3COO）2·H2O, and two moles of iron （Ⅲ） acetate basic, Fe（CHCOO）2·OH. Nanocrystalite （89 nm） Copper ferrite （less than 100%） is obtained at lower temperatures, whereas 100% copper ferrite is obtained after calcination at 1000℃. Thermal analysis （TG and DTA）, X-ray diffraction （XRD）, Fourier transform infrared spectroscopy （FTIR）, photo microscopy, magnetic and porosity obtained after calcinations at 700, 800, 900 and 1000℃ to measurements have been carried out for the specimens characterize the conversion efficiency of the powder precursors to copper ferrite. It was found that increasing temperature leads to great improvement in the magnetic properties. By increasing calcination temperature from 700～1000℃saturation magnetic flux density （Bs） increased from 17.8 to 40.8 emu/g, while remnant magnetic flux density （Br） increased from 10.1 to 17.11 emu/g.

On the comparable activity in plasmonic photocatalytic and thermocatalytic oxidative homocoupling of alkynes over prereduced copper ferrite

Despite of extensive attention on the copper-based heterogeneous oxidative homocoupling of alkynes(OHA)to 1,3-diynes,the photocatalytic OHA is scarcely investigated.By screening copper-containing spinel catalysts,we discovered that a prereduced copper ferrite(CuFe2O4)not only can catalyze the thermocatalytic OHA but also is efficient for the photocatalytic OHA under visible light irradiation.It is found that the sol-gel combustion(SG)method and the partial reduction at 250 ℃ can result in the optimal CuFe2O4-SG-250 catalyst showing high activity and stability.Surface oxidized Cu2O is evidenced to be the active species for the thermocatalytic OHA,whereas metallic copper nanopaticles(CuNPs)are identified as the active sites for the photocatalytic OHA.The efficiency of photocatalytic OHA at ambient temperature is comparable to that of thermocatalytic OHA at 120 ℃,and the CuFe2O4-SG-250 catalyst can be magnetically separated and reused at least five times.The localized surface plasmon resonance effect of CuNPs contributes to visible light-induced photocatalytic OHA.

Nano Copper Ferrite Catalyzed Sonochemical, One-Pot Three and Four Component Synthesis of Poly Substituted Imidazoles

A simple, multi component, one-pot method has been reported for the synthesis of poly substituted imidazoles in presence of magnetically separable and recyclable spinel nano copper ferrite as heterogeneous catalyst by the cyclo-condensation of benzil, aromatic aldehyde, ammonium acetate and substituted amines under ultrasonic irradiation. This method of preparation has many advantages compared to those methods which are previously reported in the literature. This methodology offers simple experimental procedure, milder reaction conditions and environmentally benign approach.

Microstructure and temperature dependence of magnetic properties of CuO-added MnZn ferrites

MnZn ferrites with the chemical formula Mn0.68Zn0.25Fe2.07O4 have been prepared by a conventional ceramic technique. Then, the effects of CuO addition on the microstructure and temperature dependence of magnetic properties of MnZn ferrites were investigated by characterizing the fracture surface micrograph and measuring the magnetic properties over a temperature ranging from 25 to 120 C. The results show that the lattice constant and average grain size increase with the increase of CuO concentration. When the CuO concentration is below 0.07 wt.%, the initial permeability and saturation magnetic flux density increase monotonously, and the temperature of the secondary maximum peak in the curve of initial permeability versus temperature and the lowest power loss shift to a lower temperature with the increase of CuO concentra-tion. However, excessive CuO concentration （0.07 wt.%） results in abnormal grain growth and porosity increase, which causes the initial permeability and saturation magnetic flux density decrease and the power loss increase at room temperature. Furthermore, the temperature of the secondary maximum peak in the curve of initial permeability versus temperature and the lowest power loss shift to a higher temperature.

Surface segregation of copper in antibacterial ferritic stainless steel

By using auger electron spectroscopy （AES） and diffusion theory to analyze the surface segregation of copper in antibacterial ferritic stainless steel, establishing a diffusion model, and calculating the activation energy of diffusion of the copper in ferrite, the affect of surface segregation on the antibacterial capabilities were researched. The results show that the concentration of the copper surface at 973 K and 1 073 K could be expressed asln X^sCu/X^bCu = k0 √Dt/d（-△Hv^Cu＋△Hf^tron＋ △Hs^Cu）/3RT , with the parameters relating to the concentration of the diffusion layer, the coefficient of diffusion, the length of diffusion, the latent heat of evaporation and the latent heat of fusion. The activation energy of diffusion of copper in ferrite is approximately 221. 688 kJ/mol. The antibacterial property of the steel is improved as the surface segregation of the copper is increased. At 1 073 K for 60 min, the concentration of the surface copper is over three times higher than the basic concentration. The antibacterial property of the stainless steel can reach approximately 99.9%.

Determination of trace impurity elements in MnZn ferrite powder by direct current glow discharge mass spectrometry

An analytical method for the determination of 26 impurity elements （such as Li, Be, Na, Mg, Al, Si, P, S, K, Ca, Sc, Ti, V, Cr, Co, Ni, Ga, Ge, Y, Nb, Mo, Ag, Cd, Sb, W and Pb） in MnZn ferrite powder by direct current glow discharge mass spectrometry （GD-MS） was established. MnZn ferrite powder was mixed with copper powder, used as a conductor, and pressed. The effects of MnZn ferrite powder preparation conditions and glow discharge parameters for the sensitivity and stability of signal analysis were investigated. By determining the choice of isotope and the application of the mass resolutions of 4000 （MR, medium resolution） and 10000 （HR, high resolution）, mass spectral interference was eliminated. The contents of impurity elements in MnZn ferrite powder was calculated by subtraction after normalizing the total signal of Mn, Zn, Fe, O and Cu. The results showed that the detection limit of 26 kinds of impurity elements was between 0.002 and 0.57 μg/g, and the relative standard deviation （RSD） was between 3.33% and 32.35%. The accuracy of this method was verified by the ICP-MS. The method was simple and practical, which is applied to the determination of impurity elements in MnZn ferrite powder.

Nano crystalline powders of NiCu ferrite and NiCuZn ferrite prepared from citrate gel method： Synthesis and cnaracterzation

Nano size nickel copper ferrite powders （NiCuFe204） and nickel copper zinc ferrite powders have been prepared by a citrate gel precursor method. The resulting powders were characterized by X-ray diffraction （XRD） and scanning electron microscope （SEM）. The results showed that nickel copper ferrites and nickel copper zinc ferrites were also in the nanosaele. The NiCu ferrite powders showed extensive XRD fine broadening and sizes of crystals were calculated （from the XRD line broadening） as 26 run-44 run over the temperature range is 200-800℃. The NiCuZn ferrite powders showed XRD line broadening and sizes of of crystals were calculated 46-65 nm over 200-800℃.

Correlation between structural phase transition and physical properties of Co^(2+)/Gd^(3+)co-substituted copper ferrite

The doping of the spinel ferrites with selective cations usually improves the properties of the parent ferrite.The effect of Co^(2+)/Gd^(3+)co-substitution on the microstructure,optical,and magnetic properties of Cu1-xCoxFe2-xGdxO4 prepared by the citrate-nitrate auto-combustion synthesis was investigated.Characterization of the samples was performed with powder X-ray diffraction(XRD),Raman and Fouriertransform infrared(FTIR)spectroscopy,field-emission scanning electron microscopy,X-ray energydispersive spectroscopy,UV-Vis spectroscopy,and a vibrating sample magnetometer.The results of XRD,Raman,and FTIR analysis show a gradual structural phase transition from a tetragonal(I41/amd)structure to a cubic(Fd3m)structure.The bandgap energy of the studied samples is in a range of 1.57-1.75 eV with a minimum in sample x=0.06 and then increases.Magnetic investigations show that the presence of Co^(2+)/Gd^(3+)cations in an octahedral site of the copper ferrite structure could increase saturation magnetization and coercive field from 567.9 Oe and 23.62 emu/g to 929.4 Oe and 28.27 emu/g,respectively.

High corrosion resistance 21%Cr-0.4%Cu ferritic stainless steel contributing to resource conservation

With prices for metal resources such as nickel and molybdenum soaring,there is a heightened sense of crisis concerning resource scarcity.While Type304,the most common stainless steel,offers excellent corrosion resistance,its price is affected significantly by the cost of nickel because of its 8%nickel content.The stainless steel that has the same corrosion resistance as that of Type304 and does not contain nickel and molybdenum has been required.JFE Steel Corporation has developed a new 21%Cr-0.4%Cu stainless steel,the world's first ferritic stainless steel,which offers equivalent corrosion resistance to Type304 while containing absolutely no nickel or molybdenum,two rare metals.The newly developed steel contains 21%chromium with the addition of 0.4% copper.The development of the steel is based on a new discovery that the passive films of stainless steels could be strengthened by the synergy effect of high chromium content and copper addition.Copper addition enriches the chromium content in passive films after field exposure.Newly developed 21%Cr-0.4%Cu stainless steel is adopted for many applications as a substitution for Type304,including commercial kitchenware,building materials and industrial machinery.The steel is expected to be a new standard of a ferritic stainless steel as a substitution for Type304.

Microstructural Development of Fe-20mass%Cr Alloys and Pure Copper Processed by Equal-Channel Angular Pressing

Microstructural development of ultra low C, N, Fe-Cr alloy and pure copper processed by equal-channel angular pressing (ECAP) have been examined focusing on the initial stage of the formation of ultrafine grain structure. Fe-Cr alloys were pressed at 423 K while pure copper at room temperature for 1 to 3 passes via the route Bc to compare at the equivalent homologous temperature. Microstructural evolutions were characterized by electron backscatter diffraction (EBSD) image and transmission electron microscopy (TEM). It was found that deformation structures were mostly deformation-induced subboundaries in both the materials after one pass, but the fraction of high-angle grain boundary became higher in the Fe-Cr alloys than in pure copper in subsequent passes by increasing misorientation of the boundaries. The more enhanced formation of high angle boundaries in Fe-Cr alloys was discussed in terms of the nature of crystal slip of FCC and BCC structures.

Weldability of Copper-bearing Aging Steel

The weldability of copper-bearing aging steel is evaluated using calculated cracking susceptibility index Pcm,oblique Y-groove cracking test,heat-affected zone （HAZ） maximum hardness measurement,submerged arc welding （SAW） test and gas metal arc welding （GMAW） test.The results show that this copper-bearing aging steel has low hardenability and cold cracking susceptibility.SAW test of 40 mm thick plate with WS03 wire matched by CHF101 flux reveals that the welded joints obtain high strength and good impact toughness at low temperature.The HAZ has no hardening but there exists a slightly softening phenomenon.Thus,line energy should be limited or controlled strictly to avoid softening behavior in HAZ during SAW.GMAW tests of 12mm and 24mm thick plates using WER70NH wire show that the tensile strength of joints reaches 720MPa,higher than the stipulated strength requirement of base metal.The average impact energy at-40℃ in the welded joints is more than 140J exceeding minimum stipulated requirement by a wide margin.There are no hardening and softening behaviors in the heat-affected zones of GMAW.All weld metals exhibit acicular ferrite （AF） plus small amount of proeutectoid ferrite （PF） structure,of which the former can significantly improve impact toughness of weld metal.The predominant microstructure in coarse grain HAZ is bainite.

Studies on the preparation of active oxygen-deficient copper ferrite and its application for hydrogen production through thermal chemical water splitting

Hydrogen generation through thermal chemical water splitting technology has recently received in- creasingly international interest in the nuclear hydrogen production field. Besides the main known sulfur-iodine (S-I) cycle developed by the General Atomics Company and the UT3 cycle (iron, calcium, and bromine) developed at the University of Tokyo, the thermal cycle based on metal oxide two-step water splitting methods is also receiving research and development attention worldwide. In this work, copper ferrite was prepared by the co-precipitation method and oxygen-deficient copper ferrite was synthesized through first and second calcination steps for the application of hydrogen production by a two-step water splitting process. The crystal structure, properties, chemical composition and δ were investigated in detail by utilizing X-ray diffraction (XRD), thermogravimetry (TG) and differential thermal analysis (DTA), atomic absorption spectrometer (AAS), ultraviolet spectrophotometry (UV), gas chro- matography (GC), and so on. The experimental two-step thermal chemical cycle reactor for hydrogen generation was designed and developed in this lab. The hydrogen generation process of water splitting through CuFe2O4-δ and the cycle performance of copper ferrite regeneration were firstly studied and discussed.

An effective catalyst carrier SiO_(2):Enhancing catalytic and combustion properties of CuFe_(2)O_(4)on energetic components

To enhance the catalytic activity of copper ferrite(CuFe_(2)O_(4))nanoparticle and promote its application as combustion catalyst,a low-cost silicon dioxide(SiO_(2))carrier was employed to construct a novel CuFe_(2)O_(4)/SiO_(2)binary composites via solvothermal method.The phase structure,morphology and catalytic activity of CuFe_(2)O_(4)/SiO_(2)composites were studied firstly,and thermal decomposition,combustion and safety performance of ammonium perchlorate(AP)and 1,3,5-trinitroperhydro-1,3,5-triazine(RDX)with it affecting were then systematically analyzed.The results show that CuFe_(2)O_(4)/SiO_(2)composite can remarkably either advance the decomposition peak temperature of AP and RDX,or reduce the apparent activation energy at their main decomposition zone.Moreover,the flame propagation rate of RDX was promoted by about 2.73 times with SiO_(2)content of 3 wt%,and safety property of energetic component was also improved greatly,in which depressing the electrostatic discharge sensitivity of pure RDX by about 1.89 times.In addition,the effective range of SiO_(2)carrier content in the binary catalyst is found to be 3 to 5 wt%.Therefore,SiO_(2)opens a new insight on the design of combustion catalyst carrier and will promote the application of CuFe_(2)O_(4)catalyst in solid propellant.

刚果(金)某铜精矿酸浸渣中铜的赋存特征及回收

刚果(金)地区主要采用湿法炼铜工艺提取铜精矿中的铜,含铜55%~65%的硫化铜精矿经过焙烧和两段酸浸后,酸浸渣中含有3%~10%的铜。以刚果(金)某铜精矿焙砂酸浸渣为研究对象,在对其进行工艺矿物学分析的基础上,采用加压浸出方式回收渣中的铜。结果表明,铜精矿焙砂酸浸渣中的铜主要以硅孔雀石、胆矾和亚铁酸铜的形式存在,三种矿物所含铜占总铜量的96.87%,其中亚铁酸铜为主要难浸矿物;酸浸时,酸用量对铜浸出率影响最大;最佳浸出条件为液固比4 mL/g、酸矿比(硫酸用量与酸浸渣的质量比)65%、浸出时间2 h、浸出温度180℃,对应的铜浸出率为94.52%,渣含铜可由处理前的7.66%降低到0.52%。

Cu对含Sn铁素体不锈钢的力学及耐腐蚀性能的影响

以0.30%Sn的430铁素体不锈钢为基础,在实验钢中添加一定量的Cu来研究Cu对实验钢力学性能和耐腐蚀性能的影响。常温拉伸实验和高温拉伸实验结果表明,Cu原子在基体中发挥固溶强化效果而增强不锈钢的抗拉强度,但同时因晶界处生成大量的富Cu相而相应降低不锈钢的塑性。实验钢的耐均匀腐蚀性能随着Cu含量的增加而呈现先提高,后降低的趋势,且在含0.45%Cu的钢中达到最佳的效果。此外,Cu对实验钢的耐晶间腐蚀性能有类似的规律,且在含0.98%Cu的钢中达到最佳的效果。

铜负载NiFe_(2)O_(4)的制备及其光催化活性

为有效解决水体抗生素污染问题,光催化降解技术为当今治理污水领域不可或缺的一部分,铁酸镍(NiFe_(2)O_(4))作为一种尖晶石型铁氧体材料,被广泛应用于光催化环境污染治理。通过简单的水热法制备不同铜含量的铜(Cu)复载NiFe_(2)O_(4)光催化材料,在模拟太阳光照射60 min下,以盐酸四环素为目标降解物,测量其降解率。在制备的样品中17%-Cu@NiFe_(2)O_(4)对四环素降解效率最佳,达到了96%,与纯相NiFe_(2)O_(4)相比降解率提升了31%。

Mechanism of oxygen releasing of copper ferrite in the formation of the corresponding oxygen-deficient compound

Copper ferrite is a promising material for hydrogen production through thermochemical water splitting. In this work, the cation distribution of copper ferrite and the corresponding oxygen-deficient compound of spinel structure was analyzed based on the crystal structural chemistry theory. The mechanism of oxygen releasing of CuO, Fe2O3, CuFe2O4 and metal (M=Ni, Mn or Zn) doped copper ferrite in the process of temperature rising was investigated by differential thermal analysis-thermogravimetry (DTA-TG). By combining the theoretical analysis with experimental results, the mechanism of oxygen releasing of copper ferrite is proposed, which is different from that of other ferrites. For copper ferrite, the oxygen releasing caused by Cu(II)→Cu(I) plays a predominant role, while for other ferrites, the oxygen releasing resulting from Fe(III)·Fe(II) is dominant.

溶胶凝胶自燃烧法合成Mn_(0.6)Cu_(0.2)Zn_(0.2)O(Fe_2O_3)_(0.98)纳米晶铁氧体及其磁性能研究

利用溶胶凝胶自燃烧法 ,在室温下直接合成了 30nm左右的Mn0 .6 Cu0 .2 Zn0 .2 O(Fe2 O3) 0 .98纳米晶铁氧体。借助于DTA -TG ,IR ,XRD和VSM技术 ,对干凝胶的热分解过程 ,自燃烧本质及合成纳米晶的磁性能进行了研究。研究表明 ,由金属的硝酸盐和柠檬酸形成的干凝胶具有自燃烧的特性。自燃烧的实质是在热诱导下的氧化还原反应。XRD结果表明 ,通过自燃烧反应可以直接获得纯的锰铜锌铁氧体相而无Fe2 O3相的存在。当对自燃烧粉进行预烧时 ,随着预烧温度的提高 ,有Fe2 O3相的出现。随着预烧温度的升高 ,Mn0 .6 Cu0 .2 Zn0 .2 O·(Fe2 O3) 0 .98铁氧体粉体的矫顽力由未经预烧时的 9.0 395kA·m- 1 线性下降到经 10 0 0℃预烧后的 4.72 46kA·m- 1 。但是 ,饱和磁化强度的变化却是先下降再升高。所获得的Mn0 .6 Cu0 .2 Zn0 .2 O(Fe2 O3) 0 .

CuO/BiFeO3异质结光催化还原溶液中U(Ⅵ)的性能

通过湿浸渍法制备了CuO/BiFeO3可见光响应异质结光催化剂,通过SEM、XRD、XPS、UV-Vis等分析手段对材料进行表征,并在室温下以氙灯为光源,探讨CuO/BiFeO3异质结复合催化剂光催化还原溶液中U(Ⅵ)的性能,并对光催化还原机理进行了初步分析。结果表明,CuO颗粒呈球状,表面光滑,为单斜晶型。BiFeO3由不规则的颗粒团聚成层状,为钙钛矿结构。与纯CuO和BiFeO3相比,含10%CuO的CuO/BiFeO3对U(Ⅵ)的光催化还原效果最好,其去除效率远高于纯CuO和BiFeO3的;在可见光照射下催化反应100min时,U(Ⅵ)的去除率达96%以上。该催化剂光催化活性的提升主要是由于在CuO和BiFeO3界面上形成的p-n异质结结构有效地抑制了光生电子与空穴的复合,增强了界面电荷传输效率,使光催化效率得到了提高。光催化剂循环使用4次后,U(Ⅵ)的去除率仍在80%左右,说明其稳定性比较好。

常温中和铁氧体法处理高浓度含铜废水的研究

通过实验研究了铁氧体法处理高浓度含铜废水的工艺条件。结果表明:在pH=10.0、n(Fe2+)∶n(Cu2+)=10、n(Fe3+)∶n(Fe2+)=1.5∶1、反应温度为30℃、搅拌时间为15 min的条件下,处理效果最佳。铜的去除率可达99.95%左右,处理后的废水中的Cu2+可从1 600 mg/L左右降至1 mg/L以下,达到GB 25467—2010的间接排放标准。对沉淀进行酸洗、水洗和干燥处理,EDS和XRD分析结果显示在此条件下能生成稳定存在的铜铁氧体。