Effect of additive on synthesis of MnZn ferrite nanocrystal by hydrothermal crystallization

1　ＩＮＴＲＯＤＲＣＴＩＯＮＷｉｔｈｒｅｇａｒｄｔｏｔｈｅｓｔｕｄｙｏｆｃｒｙｓｔａｌｇｒｏｗｔｈｕｎｉｔｓ,ｒｅｓｅａｒｃｈｅｒｓｍａｉｎｌｙｃｏｎｃｅｎｔｒａｔｅｏｎｔｈｅｄｉｓｓｏｌｕｔｉｏｎｏｆｓｏｌｕｔｅ ,ｔｈｅｆｏｒｍａｔｉｏｎｏｆｇｒｏｗｔｈｕｎｉｔｓａｎｄｔｈｅｔｒａｎｓｐｏｒｔａｔｉｏｎｏｆｔｈｅｃｒｙｓｔａｌｇｒｏｗｔｈｕｎｉｔｔｏｔｈｅｉｎｔｅｒｆａｃｅ ,ａｓｗｅｌｌａｓｔｈｅｃｏｎｇｒｕｅｎｃｙｏｆｔｈｅｇｒｏｗｔｈｕｎｉｔｓｏｎｔｈｅｉｎｔｅｒ ｆａｃｅｓｏｆｔｈｅｃｒｙ…     

Synthesis and characterization of arsenate antimonic acid AAAc(1 : 1)

The AAAc(1 : 1) was synthesized in water by As₂O₃ and Sb₂O₃ with molar ratio of 1 : 1. AAAc(1 : 1) was characterized by Raman, IR, TG/DTG, DSC, XPS and XRD. The results show that there are four peaks to v _s of As-OH, As-O-Sb, Sb-OH and Sb-O-Sb in Raman spectra of AAAc(1 : 1) at 100 – 1 000 cm⁻¹. The solution of AAAc(1 : 1) was also titrated with KOH solution. The titration results show that AAAc(1 : 1) is a hexabasic acid with dissociation constants of k ₁=3.62 × 10⁻², k ₂=3.05 × 10⁻³, k ₃=6.43 × 10⁻⁶, k ₄ =9.78 × 10⁻⁸, k ₅=1.32 × 10⁻¹¹, k ₆=3.87 × 10⁻¹². AAAc(1 : 1) has a good solubility and stability in water, its solid obtained by free volatilizing water from its solution under air at ambient temperature is amorphous. Chemical and thermal analysis show that the composition of AAAc(1 : 1) is As₂O₅ · Sb₂O₅ · 8H₂O in air at 25 °C. AAAc(1 : 1) has the structure of AsO(OH)₂-OH-Sb(OH)₄-O-Sb(OH)₄-OH-AsO(OH)₂ or As(OH)₃-O-Sb(OH)₄-O-Sb(OH)₄-O-As(OH)₃ (isomerism) through experimental determination and geometry optimization. Foundation item: Project(50274075) supported by the National Natural Science Foundation of China     

Electrochemical behaviors of gold and its associated elements in various complex agent solutions

1　INTRODUCTIONGoldisquitestableanddifficulttodissolveinacommonmineralacid .However ,becausethereisadelectroniclayerunfilledingoldatomicstructure ,goldcanbecombinedwithmanychemicalagentstoformstablecomplexions,causingthepotentialofgoldinasolutiontodecreaseandgoldtodissolveinthesolutioneasily .Basedonthisprinciple ,cyanideisanefficientlixiviatingagentofgold ,andhasbeenwidelyusedtoextractgoldfrom primaryandsecondaryresources .However ,itisthemosttoxicandnotbeneficialtoen vironmentprotection…     

Template effect on structure and morphology of Ni(OH)2 powders prepared by hydro-chemical method

The template effect controlling the structure and morphology of ultrafine particles was described. Ni(OH)₂ powders were prepared by NH₃ coordination-precipitation method. The effects of SO ₄ ²⁻ , NO ₃ ⁻ , Cl⁻, NH₃, pH value on Ni(OH)₂ structure and morphology were investigated experimentally, explained with the theoretical model that the growth units were the polyhedral structure of coordination anions. The results showed that the structure and morphology of Ni(OH)₂ were effectively controlled by the growth units, the dimensions and the linking patterns of the growth units vary with the changes of physical and chemical conditions in the aqueous solution. Foundation item: The National Natural Science Foundation of China(No.59774018) Biography of the first author: LIU Zhi-hong, professor, born in 1963, majoring in hydrometallurgical technology and control of structure and morphology of powders.     

Electrochemical kinetics of gold dissolving in alkaline thiourea solution

1 INTRODUCTIONEssentially , determination of electrode reac-tion mechanism is just the determination of thecourse of electrode reaction and the rate-determi-ning step[1 5]. Based on the previous results[6 11],gold dissolution mechanism undergoes the follow-ing courses in alkaline thiourea solution: adsorp-tion of thiourea on active points of electrode sur-face and formation of Au[SC(NH2)2]ads; chargetransfer fromactive gold atomto thiourea moleculeand formation of Au[SC(NH2)2]a+ds; Au-…     

Optimization of efficient stable reagent of alkaline thiourea solution for gold leaching

1　INTRODUCTIONThiourea ,asanontoxic goldleachingreagentsubstitutingcyanide ,hasattractedtheinterestofmanyresearchersallovertheworldsincethedissolu tionofgoldinthioureasolutionwasfirstreportedin194 1,andaseriesofstudiesonthetheoryandtech nologyforleachinggoldbythioureahavebeencon ducted[1 3] .Mostreportson golddissolutioninthioureasolutionwereconcernedwithacidicmedia .Itwasdifficultforgoldtodissolveinalkalinesolutionbecauseofthepassivationofelementsulfurproducedbytheirreversibledecompositi…     

Synthesis and coloring properties of Cd（S1-xSex） pigments by precipitate-hydrothermal method

Cd（S1-xSex） pigments （red to yellow） were synthesized by precipitate-hydrothermal method. The structure, morphology and hue of the powder were characterized by X-ray diffractometry （XRD）, scanning electron microscopy （SEM）, energy dispersive X-ray spectroscopy （EDAX） and CIE chromaticity. The optimum synthesis conditions were obtained and reaction mechanism was further analyzed as well. The results show that molar ratio of S to Se, pH value and hydrothermal reaction conditions have great effects on the hues of the pigments. Pigments with vivid hues are obtained under the conditions that pH value is about 13.0, hydrothermal reaction condition is at 140 ℃ for 4 h or at 160 ℃ for 6 h. The reaction mechanism is that Se^2- of Cd（S1-xSex） substitutes S^2- of CdS and then forms a continuous solid solution.     

Characterization and Electrochemical Properties of LiMn2O4 Thin Films Prepared by Solution Deposition

1 IntroductionThin-filmlithium-ion batteries have attracted greatattention of researchfor possible use inimplantable medi-cal devices , CMOS-based integrated circuits ,radio fre-quency (RF) identification tags for inventory control andanti-theft protection[1],etc. Li Mn2O4thin films , aspromising cathode materials for thin-filmlithium-ion bat-teries, have been prepared by a few methods such aspulsedlaser deposition[2 ,3],electrospraying[4-9],RF mag-netron sputtering[10], laser ablation[11]…     

Preparation of AgSnO2 composite powders by hydrothermal process

Silver-tin oxide powders were synthesized by the hydrothermal method with Ag（NH3）2^＋ solution and Na2SnO3 solution as raw materials and Na2SO3 as reductant. The precipitation conditions of Na2SnO3 solution and the reduction conditions of Ag（NH3）2^＋ were also investigated. The powders prepared were characterized by differential thermal analysis （DTA）, X-ray diffraction analysis （XRD）, scanning electron microscope （SEM） and energy spectrum analysis, The results show that pH value of the solution is a key parameter in the formation of Sn（OH）4 precipitate and the reduction reaction of Ag（NH3）2^＋ can release H^＋ ions, which results in synchronous precipitation of Sn（OH）6^2- as Sn（OH）4. The reduction of Ag（NH3）2^＋ and precipitation of Na2SnO3 occur simultaneously and the coprecipitation of silver and tin oxide is reached by the hydrothermal method. The silver-tin oxide composite powders have mainly flake shape of about 0.3 μm in thickness and there exists homogeneous distribution of tin oxide and silver in the powder synthesized.     

Surface modification of magnesium hydroxide by γ-aminopropyltriethoxysilane

Magnesium hydroxide（MH）,which is commonly used as a halogen-free flame retardant filler in composite materials,was modified by silanization reaction with γ-aminopropyltriethoxysilane （γ-APS） in aqueous solution at different pH values （pH range from 8.0 to 12.0）. The surface properties of grafted γ-APS on MH surface as a function of solution pH value were studied using elemental analysis,Fourier transform infrared spectroscopy and zeta potential measurement. The results show that hydrolysis and condensation of γ-APS are activated in alkaline solution and lead to multilayer adsorption of γ-APS molecules on the surface of MH. The type of adsorption orientation of γ-APS on MH surface is a function of coverage density that is altered by changing solution pH value. At low coverage density （e.g. 55 nm^-2）,γ-APS molecules are preferentially adsorbed to the surface with the silicon moiety towards the surface,and increasing coverage density （e.g. 90 nm^-2） leads to parallel orientation. At an even higher coverage density （e.g. 115 nm^-2）,γ-APS molecules bond to the surface with the amino moiety towards the surface.     

Thermodynamic equilibrium of bismuth hydrometallurgy in chloride and nitrate solutions

Simultaneous equilibrium was applied to the thermodynamic analysis and calculation of Bi( Ⅲ )-X(Cl- ,NO3- )-H2O systems, based on which the diagrams of the logarithm of equilibrium concentration of Bi( Ⅲ ) of series precipitation vs pH value of these two systems at 25 ℃ were obtained, and the pH ranges of the stable zones of various precipitations were analyzed and determined. In Bi( Ⅲ )-Cl -H2O system, the variations of c0 (Bi3 ) and c0 (Cl-) have little effect on the equilibria of Bi(OH)3-solution and BiOOH-solution, but has great influence on the equilibrium of BiOCl-solution. However, in Bi( Ⅲ )-NO3-H2O system, the variations of c0 (Bi3 ) and C0 (NO3-)have little effect on equilibria of Bi(OH)3-solution, BiOOH-solution and Bi2O3-solution. When pH value is high,Bi2O3 is the thermodynamic stable phase, its stable zone is the widest, almost including the stable zones of BiOCl or BiONO3, Bi(OH)3 and BiOOH. Bi(OH)3 cannot be obtained from Bi( Ⅲ )-Cl--H2O system, even strong alkaline media. Bi2O3 can be obtained from the solution directly, and highly pure BiOCl or BiONO3 can also be obtained through strictly controlling pH value.     

Preparation of ITO nano-powders by hydrothermal-calcining process

1 INTRODUCTIONSn-doped In2O3(ITO) is one kind of n-typesemiconductor material[1].It has excellent electro-optical properties , such as electrical conductivityand high transparency under visible light[2],andiswidely used in electronic , transparent electrode ,solar cells and electro-irradiance , especially inscreen display[3 ,4].Recently nearly half of the met-al indium has been used to prepare ITO materialsin the developed countries[5], such as Japan, A-merica ,France and so on.So the…     

Potential control flotation of galena in strong alkaline media

The electrochemical oxidation of galena in collectorless and collector flotation systems, particularly in strong alkaline media, was studied. The results show that, with pH value higher than 12.5 and potentials below 0.17 V, the oxidation products of galena are elemental sulfur and HPbO2^- . Elemental sulfur was present on the mineral surface in excess of oxidized lead species due to dissolution of HPbO2^- , which is beneficial to the flotation of galena. Under the same conditions, sphalerite and pyrite were depressed as a result of significant surface oxidation. Diethyldithioearbamate (DDTC) was found to be the most suitable collector for galena flotation in strongly alkaline media. The very potential produced hydrophobic PbD2-the surface reaction produet of DDTC with galena, is 0 to 0.2 V. Meantime DDTC can depress the surface over-oxidation of galena.Investigations also indicate that, in the range of - 0.9 V to 0.6 V, hydrophobic PbD2 can be firmly adsorbed on galena.     

Chemial Bond and Stability of Adsorption of [Au（ AsS3 ）]^2- on the Surface of Kaolinite

Density function theory and discrete variation method (DFT-DVM) were used to study the adsorption of [Au( AsS3 )]^2- on the surface of kaolinite. The correlation among structure, chemical bond and stability was discussed. Several models were selected with [ Au( AsS3)]^2- in different directions and sites. The results show that the models with gold on the edge of kaolinite basal layer contain pincerlike bond among gold and several oxygen atoms and form strong Au - 0 covalent bond, so these models are more stable than those with gold above or under the layer. The models with gold near to [ AlO2(OH)4] octahedra are more stable than those with gold near to the vacancy withont aluminium. These two stable tendencies in kaolinite- [ Au( AsS3)]^2- are stronger than that in kaolinite-Au systems. The interaction between [ Au( AsS3 )]^2- and kaolinite is stronger than that between gold and kaolinite, and this interaction is strong enough to form the surface complexes.     

Experiments and reaction characteristics of liquid phase simultaneous removal of SO<Subscript>2</Subscript> and NO

Experiments of simultaneous removal of SO₂ and NO from simulated flue gas, using NaClO₂ solution as the absorbent, were carried out in a self-designed bubble reactor, and high simultaneous removal efficiencies of SO₂ and NO were obtained under the optimal experimental conditions. The mechanism of simultaneous removal based on NaClO₂ acid solutions was proposed by analyzing the removal products. Possibility and limitation of the desulfurization and denitrification using NaClO₂ acid solutions were calculated by thermodynamic methods. Experimental results of reaction kinetics for simultaneous desulfurization and denitrification indicated that the oxidation-absorption processes of SO₂ and NO were divided into two zones, namely the fast and slow reaction zones. In the slow reaction zones both were zero order reactions, and in the fast reaction zones, the reaction order, rate constant and activation energy of SO₂ reaction with absorbent were 1.4, 1.22 (mol·L⁻¹)^−0.4·s⁻¹ and 66.25 kJ·mol⁻¹, respectively, and 2, 3.15×10³ (mol·L⁻¹) ⁻¹·s⁻¹, and 42.50 kJ·mol⁻¹ for NO reaction, respectively. Supported by the National High-Tech Research and Development Program of China (“863” Project) (Grant No. 2007AA061803)     

Formation mechanism of barium titanate nanocrystals under hydrothermal conditions

Growth units and the crystallization habit of BaTiO₃ nanocrystals have been investigated. It has been proposed that the growth units of BaTiO₃ were surface hydroxylated Ti(OH)₆²⁻ octahedra. The relationship between crystal morphology and the variation of the current intensity in the solution has been obtained through the measurement of the OH⁻ in the solution and the hydrothermal experiment with superimposed direct electric field. Based on the computation of the stability energy of the growth units, the relationship between the crystallized morphology of crystallites and the most favorable growth units under different conditions has been derived. It has been found that there is structure similarity between anatase (TiO₂) and BaTiO₃ from the crystal chemistry viewpoint, so they are soluble in each other, which can serve as a reasonable explanation for the abnormal phenomenon of the retention of cubic substable phase at room temperature. Project supported by the National Natural Science Foundation of China.     

Microwave digestion polarography for determining seven trace elements in Salvia Miltiorrhiza Root and compound Salvia Miltiorrhiza Root injection simultaneously

The sensitive second derivative waves of Cu(Ⅱ),Pb(Ⅱ),Cd(Ⅱ),Ni(Ⅱ),Zn(Ⅱ),Fe(Ⅱ)and Mn(Ⅱ),forming in the substrate solution(pH=9.26)consisting of ammonia,ammonium chlorid,gelatin and ascorbic acid were researched.The peak potentials of the polarographic waves of the seven ions are at about 0.48,0.63,0.79,1.04,1.28,1.44 and 1.60 V respectively.Combining with microwave technique,a new method for the simultaneous determination of the seven trace elements in Chinese traditional medicine was developed.The method is easy to operate,rapid,simple and convenient.When the signal-to-noise rate equals 3,the detection limits of Cu,Pb,Cd,Ni,Zn,Fe and Mn are 4.2×10 3,5.3×10 3,2.1×10 3,5.8×10 4,3.0×10 3,7.7×10 4 and 1.1×10 3 μg/mL respectively.Well linear relationships exist between the concentrations and the peak currents when Cu,Pb,Cd,Ni,Zn,Fe and Mn concentrations are within 8.5×10 3 10,9.7×10 3 10,4.5×10 3 10,1.2×10 3 10,6.4×10 3 10,1.5×10 3 10 and 2.8×10 3 10 μg/mL,respectively.The method has been used to the simultaneous determination of the seven trace elements in Salvia Miltiorrhiza Root and compound Salvia Miltiorrhiza Root injection,the relative standard deviations(RSDs)of the Cu,Pb,Cd,Ni,Zn,Fe and Mn in the two medicines are 3.9% and 5.8%,4.0% and 4.1%,4.3% and 5.7%,4.9% and 5.3%,4.4% and 4.7%,3.5% and 4.0%,0.51% and 2.8%,respectively;the comparisons of the determination results with the values obtained by the standard method indicate that the presented method has very well veracity.     

Spectra and DNA-binding properties of two novel mixed-ligand complexes containing organosulfonate

Two novel mixed-ligand complexes, [M(phen)₂(ans)₂]·H₂O (M = Cd(II) 1, Zn(II) 2; phen is 1, 10-phenanthroline, and ans is 4-aminonaphthalene-1-sulfonate), were obtained from the reaction of 1, 10-phenanthroline, sodium 4-aminonaphthalene-1-sulfonate tetrahydrate and acetate in mixed solvents. Interaction of the complexes with calf thymus DNA (ctDNA) were investigated using UV-vis absorption spectra, luminescence titrations, steady-state emission quenching by [Fe(CN)₆]⁴⁻, DNA competitive binding with ethidium bromide (EB) and viscosity measurements. The experimental results indicate that there exist two interaction modes between the complexes and DNA, namely the electrostatic interaction and intercalation, with the binding constants of 1.82 × 10⁵ M⁻¹ for 1 and 4.78 × 10⁴ M⁻¹ for 2 in buffer of 50 mM NaCl and 5 mM Tris-HCl (pH 7.0). Funded by Key Project of the National Natural Science Foundation of China (No. 60537050)     

Determination of the entropy change for electrode reaction and dilute enthalpy of some ions by thermo-eletrochemical technology

Based on thermo-electrochemical equation for an electrode reaction, the entropy change of it can be obtained by the thermo - electrochemical technology (TECT). The entropy changes of Fe (CN) ₆ ⁻³ /Fe (CN) ₆ ⁻⁴ , H⁺/H₂(P⁰), Cu⁺²/Cu and Zn⁺²/Zn electrode reaction systems and the dilute enthalpies of the H⁺, Cu²⁺ and Zn²⁺ ions under the ion concentrations studied have been determined by a specially designed thermo-electrochemical equipment. The enthalpy change and entropy change for the five systems at unlimitedly diluted concentrations agree well with the literature. Project supporterd by the National Natural Science Foundation of China Synopsis of the first author Fang Zheng, Ph. D. and professor, born in April 1944, majoring the metallurgical thermodynamics and thermoelectrochemistry, supervised and participated in three projects supported by the National Natural Science Fundation of China and some other projects. More than 70 academic papers have been published.     

Microstructural Probing of （1-x） GeS2- x Ga2S3 System Glasses By Raman Scattering

Roman scattering measurement of （ 1 - x ） GeS2-x Ga2S3 system glasses was conducted in order to understand the microstructural change caused by the addition of Ga2S3 . According to the change of Raman spectra with the addition of Ga2S3, two main structural transformations were deduced ： the gradual enhancement of ethane- like structural units S3 Ge- GeS3 （ 250 cm ^- 1） and S3 Ga- GaS3 （270 cm ^- 1 ） and the appearance of charge imbalanced units [ Ga2 S2 （ S1/2 ）4 ]^2- and [Ga（ S1/2 ）4 ]^- . And this change of structural aspect seems to give as a clue to understanding the cause of the increased rare-earth solubility.