棒状氧化锌纳米材料的制备及表征

分别以Zn(Ac)2.2H2O和Zn(NO3)2.6H2O为锌源,利用简易的低温液相法制备了2种不同形貌的ZnO纳米棒状结构。XRD衍射图谱表明,所得的ZnO纳米棒具有六角纤维锌矿结构;通过SEM观察可知,以Zn(Ac)2.2H2O为锌源制备的ZnO纳米棒,长度1~5μm,直径50~100 nm;以Zn(NO3)2.6H2O为锌源制备的ZnO纳米棒,长度0.5~1μm,直径40~60 nm。     

Influence of La-dopant on the material characteristics and supercapacitive performance of MnO<Subscript>2</Subscript> electrodes

Manganese dioxide was synthesized by electrodeposition method with Mn (CH3COO)2?4H2O as a raw material. La(NO3)3?6H2O was doped in electroyte during the preparing process to improve the performance of MnO2 electrodes. The micrographs, crystal structure and element content of electrodes were analyzed by SEM, XRD and atomic absorption spectroscopy, respectively. It is found that the La content ratio in the dioxide can be easily controlled by adjusting the composition of the plating solution. Appropriate amoun...     

Thermal Behavior Study of Carbonate Inorganic Materials

The thermal decomposition processes of(MgCO_3)_4·Mg(OH)_2·5H_2O(MCH),5ZnO·2CO_3·4H_2O(ZCH),NiCO_3·2Ni(OH)_2·4H_2O(NCH),PbCO_3(LC)and [Cr(OH)_5]_2·CO_3·8H_2O(CC)were studied via TG-DSC.The results of research imply that MCH has the largest capacity of heat absorption and ZCH is second to MCH among the studied materials.The non-isothermal kinetic parameters of MCH and ZCH were calculated by Kissinger and Ozawa methods.Furthermore,thermal decomposition mechanisms of MCH and ZCH were investigated by Coats-Redfern method.Due to the large specific heat capacity,MCH and ZCH are promising to be used as a coolant in extinguishant formulations.     

Preparation of mullite whiskers and their enhancement effect on ceramic matrix composites

Mullite whiskers were facilely prepared by sintering kyanite at high temperature, with the addition of AlF3·3H2O. The as-prepared whiskers have been characterized systematically in terms of phase composition, morphology, and structure. Results showed that the morphology and size of mullite whiskers were strongly depended on the content of AlF3·3H2O and sintering temperature. At temperatures in the range of 1 100 to 1 500 ℃ with 4 wt% addition of AlF3·3H2O, the well-shaped mullite whiskers were obtained. For an instance, the mullite whiskers with 5-10 μm in length and 0.1-0.2 μm in cross-section could be formed at 1 400 ℃, with 4 wt% addition of AlF3·3H2O. Moreover, results showed that the addition of mullite whiskers into ceramic matrix enhanced its fracture toughness significantly.     

Effects of Adhesive Composition on Green Joining of CePO4-ZrO2 Ceramics

Green bodies of 25% CePO4/ZrO2 and ZrO2 ceramics were joined at 1450℃ for 120 min without applied pressure by using mixed powders slurries composed of CePO4 and ZrO2. The effects of CePO4/( CePO4 ZrO2 ) ratio of the adhesive on the bond strength of the joints were investigated. Maximum bond strength of 414 MPa was obtained by joining an adhesive with the ratio of 0. 5 Under the experimental conditions, the grain size of the particles grown in the joint was smaller than that in joined ceramics. The microstructure of the joint was more homogeneous than that of the matrix and without obvious crack, pores and other defects.     

Preparation and Characterization of Nanosized Hydroxyapatite Particles in AOT Inverse Microemulsion

1　IntroductionSynthetichydroxyapatite (HAP) ,whichisthemajorconstitutionofnaturalboneandteeth ,iswell knownasbiocompatibleandbioactivematerialthathasbeenwidelyusedinmanyclinicalapplications[1 3] .Forexample ,po roushydroxyapatitehasbeenusedinbone ingrow…     

Preparation and microstructure of spinel zinc ferrite ZnFe<Subscript>2</Subscript>O<Subscript>4</Subscript> by Co-precipitation method

Spinel zinc ferrites ZnFe₂O₄, prepared by co-precipitation method using the zinc nitrate Zn(NO₃)₂·6H₂O and ferric nitrate Fe(NO₃)₃·2H₂O as the raw materials, were characterized by the thermo gravimetric analysis (TG) and differential scanning calorimeter (DSC), X-ray diffraction (XRD) and scanning electron microscope (SEM). The influence of synthesis conditions, such as Zn/Fe molar ratio, pH value, the sintering temperature and time, on the microstructures was detailedly investigated. The relationships between the microstructures and the synthesis conditions were discussed. The results show that the pure spinel zinc ferrites ZnFe₂O₄ are formed when the Zn/Fe molar ratio is 1.05:2 at pH=8.5 or Zn/Fe molar ratio is 1:2 at Ph=9-10, and the precursors are sintered at 1100 °C for 4 h. Especially no other phases are observed when the Zn/Fe molar ratio is 1:2 at pH=10 and the precursor is sintered above 700 for 4 °C h. The higher sintering temperature and longer sintering time contribute to grain growth.     

Effect of CaCO3 on hydration characteristics of C3A

Hydration products and morphology characteristics of C₃A (tricalcium aluminate)-CaCO₃-H₂O system were studied by means of XRD, DSC, FTIR spectrum analysis and SEM. The results indicate that, the new phases, i.e., C₃A·0.5CaCO₃·0.5Ca(OH)₂·11.5H₂O and C₃A·CaCO₃·11H₂O are found in this system due to the activity of CaCO₃; the formation of C₄AH₁₃ and C₂AH₈ is prohibited and the generation of C₃AH₆ is delayed in the early hydration process. C₃A·0.5CaCO₃·0.5Ca(OH)₂·11.5H₂O is not stable and will be totally transferred within 24 h; C₃A·CaCO₃·11H₂O exists stably once formation, and its flake-like crystalline phases in the early hydration transform to long rod shape, and to finally fine-needle at 28 d.     

Synthesis and luminescence properties of red phosphor CaO: Eu3+

Ca(NO₃)₂·4H₂O, Eu(NO₃)₃ and H₂C₂O₄·2H₂O were adopted to synthesize CaO: Eu³⁺ with the chemical co-precipitation method, and the effects of the calcination temperature and Eu³⁺ doping concentration on the phosphor structure and its luminescent properties were investigated by TG-SDTA, XRD, and PL-PLE. The results confirm that the Eu³⁺ ions as luminescent centers substitutes Ca²⁺ sites without changing the crystal structure of cubic CaO. The optimum calcination temperature and the optimum concentration of Eu³⁺ are 1 100 ° and 1 mol%, respectively, under which the best crystallinity and highest PL intensity appeared. The maximum emission wavelength is 592 nm (⁵D₀→⁷F₁) which is excited by xenon lamp with the wavelength of 200–280 nm, indicating that the Eu³⁺ ion mainly locates in the symmetric position (O_h) in the crystal lattice of CaO. Funded by the Science and Technology Bureau of Sichun Province(No. 2006J13-059) and Education Bureau of Sichun Province (No. 2006A094)     

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…     

Preparation of calcium phosphate coating on pure titanium substrate by electrodeposition method

The influences of pH value, electrolyte temperature and loading time on depositing calcium phosphate coating on pure titanium substrate by electrodeposition process were investigated. The process was carried out with an electrochemical work-station supplying a direct current power at potential of -0.8V (vs SCE). The electrolyte consists of 7 mmol·L-1 CaCl2·2H2O, 3 mmol·L-1 Ca(H2PO4)2·H2O and 2.5% H2O2. NaOH and HCl solutions were used to adjust pH value. The deposited samples were characterized by X-ray diffraction and scanning electron microscope. The comparison of the deposits obtained at lower and higher pH values demonstrates that the crystallization process at the interface is favoured by high pH value. With temperature increasing, the deposited hydroxyapatite is occasionally of plate-like shape, and the width and the length of the deposited calcium phosphates at 65 ℃ are larger than those at 55 ℃. Therefore, it is confirmed that the morphology and microstructure of electrochemically deposited calcium phosphates can be regulated. Additionally, the coating formed in electrolyte with H2O2 additive is homogeneous and the evolution of H2 bubble can be eliminated.     

Thermochemical Study of Mixed Ligand Complexes of Rare Earths with Glycine and L-alanine

In order to obtain the standard molar enthalpies of formation of Rare-Earth amino acid coordination compounds, precise isothermal solution-reaction calorimetric method was used. The value of Δ_rH _m ^Θ of two coordination reactions was determined at T=298.2 K. From the experimental results and other auxiliary values, the standard molar enthalpies of formation of Ln(Gly)_5/2(Ala)_3/2(ClO₄)₃·H₂O(s) [Ln=La, Yb] at T=298.2 K were obtained. The values of them is to be Δ_rH _m ^Θ [La(Gly)_5/2(Ala)_3/2(ClO₄)₃·H₂O(s)]=−3545.45 kJ/mol and Δ_rH _m ^Θ [Yb(Gly)_5/2(Ala)_3/2)(ClO₄)₃·H₂O(s)]=−3793.81 kJ/mol, respectively. QU Jing-nian: Born in 1954 Funded by the Teaching and Research Award Program for Outstanding Young Professors in High Education Institute, Ministry of Education, P. R. China     

Electrochemical performance of LiFePO4/（C＋Fe2P） composite cathode material synthesized by sol-gel method

A LiFePO4/(C+Fe2P) composite cathode material was prepared by a sol-gel method using Fe(NO3)3·9H2O,LiAc·H2O,NH4H2PO4 and citric acid as raw materials,and the physical properties and electrochemical performance of the composite cathode material were investigated by X-ray diffractometry(XRD),scanning electron microscopy(SEM),transmission electron microscopy(TEM) and electrochemical tests.The Fe2P content,morphology and electrochemical performance of LiFePO4/(C+Fe2P) composite depend on the calcination tempera...     

The influence of Ce(NO3)3·6H2O on the inhibitive effect of Ca(NO2)2 in simulated concrete pore solution

The effects of cerium nitrite on corrosion behaviors of carbon steel in simulated concrete pore solutions were studied with the methods of linear polarization, electrochemical impedance spectroscopy and surface analysis. In pore solutions in the presence of Ce(NO3)3?6H2O, the corrosion potential, polarization resistance and impedance of carbon steel obviously increased in contrast to the situation in the absence of cerium salts. The pore solution with [NO2-] / [Cl-] = 0.3 and 0.1% Ce(NO3)3?6H2O, carbon steel shows better corrosion resistance than that in the pore solution with [NO2-] / [Cl-] = 0.6, which indicates that a small amount of Ce(NO3)3?6H2O in pore solutions can effectively promote passivation of the steel and reduce the threshold [NO2-] / [Cl-] ratio for corrosion control. The surface layer formed in cerium salt containing pore solutions is more compact and smooth and 1.36%Ce is examined on the sample surface. The addition of 0.1% Ce(NO3)3?6H2O in pore solutions can decrease the corrosion rate of steel in pore solutions and has little influence on pH change of the solutions. However, more cerium nitrate addition above 0.1% may result in pH decrease of the solution.     

Recovery of copper sulfate after treating As-containing wastewater by precipitation method

The solid sodium hydroxide neutralized acidic As-containing wastewater till pH value was 6. Green copper arsenite was prepared after copper sulfate was added into the neutralized wastewater when the molar ratio of Cu to As was 2:1 and pH value of the neutralized wastewater was adjusted to 8.0 by sodium hydroxide. The arsenious acid solution and red residue were produced after copper arsenite mixed with water according to the ratio of liquid to solid of 4:1 and copper arsenite was reduced by SO₂ at 60 °C for 1 h. The white powder was gained after the arsenious acid solution was evaporated and cooled. Copper sulfate solution was obtained after the red residue was leached by H₂SO₄ solution under the action of air. The results show that red residue is Cu₃(SO₃)₂·2H₂O and the white powder is As₂O₃. The leaching rate of Cu reaches 99.00% when the leaching time is 1.5 h, molar ratio of H₂SO₄ to Cu is 1.70, H₂SO₄ concentration is 24% and the leaching temperature is 80 °C. The direct recovery rate of copper sulfate is 79.11% and the content of CuSO₄·5H₂O is up to 98.33% in the product after evaporating and cooling the copper sulfate solution.     

Co-precipitation/hydrothermal synthesis of BiFeO<Subscript>3</Subscript> powder

A coprecipitation/hydrothermal route was utilized to fabricate pure phase BiFeO3 powders using FeCl3·6H2O and Bi（NO3）3·5H2O as starting materials, ammonia as precipitant and NaOH as mineralizer. The synthesized powders were characterized by XRD, SEM and DSC-TG analysis. In the process, single-phase BiFeO3 powders could be obtained at a hydrothermal reaction temperature of 180 ℃, with NaOH of 0.15 mol/L, in contrast to 200 ℃ and 4 mol/L for conventional hydrothermal route. Meanwhile, the micro-morphology of synthesized BiFeO3 powders changed with different reaction temperatures and concentrations of NaOH. The N6el temperature, Curie temperature and decomposition temperature of the synthesized BiFeO3 powders were detected to be 301 ℃, 828 ℃ and 964 ℃, respectively. The hydrothermal reactions mechanism to fabricate BiFeO3 powders were discussed based on the in-situ transformation process.     

NMR research on cement clinker and its structures in early age hydration

Clinker has long been regarded as a critical factor for cement hydration and solidification.α-C2S and β-C2S in 2CaO·SiO2(C2S) phase and C3S Monoclinic 1(C3S M1) and C3S Monoclinic 3 (C3S M3) in 3CaO·SiO2 (C3S) phase were clearly recorded in the 29Si MAS NMR spectra.The content of C3S phase in the clinker deduced from the fine peak analysis coincides with the phase quantification analysis calculated by the Taylor-Bogue method based on XRF,which also accords to the statistical data in industrial production.NM...     

Co2O3-doping effect on the formation of 3CaO·3Al2O3·CaSO4

The Co₂O₃-doping effect on the formation of 3CaO·3Al₂O₃·CaSO₄ from CaCO₃-Al₂O₃-CaSO₄·2H₂O mixtures was investigated by means of SO₂ emission behavior, chemical analysis, X-ray diffraction, differential thermal analysis and scanning electron microscopy. The experimental results show that Co₂O₃ addition increases the reactivity of the CaCO₃-Al₂O₃-CaSO₄·2H₂O system significantly, by reducing SO₂ emissions in combustion and f-CaO contents in the clinkers, promoting the nucleation and growth of 3CaO· 3Al₂O₃·CaSO₄, and intensifying the formation of 3CaO·3Al₂O₃·CaSO₄. Moreover, Co₂O₃ addition lowers the formation temperature of 3CaO·3Al₂O3·CaSO₄ by 18 °C, and similarly increases the thermal stability of it at a wider temperature range.     

Preparation of ZrB<Subscript>2</Subscript>-SiC Powders via Carbothermal Reduction of Zircon and Prediction of Product Composition by Back-Propagation Artificial Neural Network

Phase pure ZrB₂-SiC composite powders were prepared after 1 450 °C/3 h via carbothermal reduction route, by using ZrSiO₄, B₂O₃ and carbon as the raw materials. The influences of firing temperature as well as the type and amount of additive on the phase composition of final products were detailedly investigated. The results indicated that the onset formation temperature of ZrB₂-SiC was reduced to 1 400 °C by the present conditions, and oxide additive (including CoSO₄·7H₂O, Y₂O₃ and TiO₂) was effective in enhancing the decomposition of raw ZrSiO₄, therefore accelerating the synthesis of ZrB₂-SiC. Moreover, microstructural observation showed that the as-prepared ZrB₂ and SiC respectively had well-defined hexagonal columnar and fibrous morphology. Furthermore, the methodology of back-propagation artificial neural networks (BP-ANNs) was adopted to establish a model for predicting the reaction extent (e g, the content of ZrB₂-SiC in final product) in terms of various processing conditions. The results predicted by the as-established BP-ANNs model matched well with that of testing experiment (with a mean square error in 10^-3 degree), verifying good effectiveness of the proposed strategy.     

Mg<Subscript>2</Subscript>(OH)<Subscript>2</Subscript>CO<Subscript>3</Subscript>·3H<Subscript>2</Subscript>O whiskers growth mechanism

From the perspective of growth units, the growth mechanism of Mg₂(OH)₂CO₃·3H₂O whisker is investigated in this paper. Results show that the growth morphology of Mg₂(OH)₂CO₃·3H₂O whisker is consistent with the model of anion coordination polyhedron growth units. The growth solution Raman shift of Mg₂(OH)₂CO₃·3H₂O was monitored using Raman spectroscopy. The growth units are [Mg-(OH)₄]^2- and H₂CO₃. The growth process of Mg₂(OH)₂CO₃·3H₂O whisker is as follows: growth unit [Mg-(OH)₄]^2- first incorporates into the larger dimension [Mg-(OH)₄] _n ^2- , then the [Mg-(OH)₄] _n ^2- combines with H₂CO₃ into a linear skeleton Mg₂(OH)₂CO₃ in the same line. Mg₂(OH)₂CO₃ combines with H₂O by hydrogen bonds and ultimately transforms into Mg₂(OH)₂CO₃·3H₂O whisker. Magnesium carbonate whiskers have a layered structure, each of which is made of magnesium, carbon, oxygen, with H₂O in between each layer. When skeletons are superimposed within the same plane as a parallelepiped one, they grow into solid cuboid-shaped whiskers. When the parallelepiped skeletons planes combine with each other through the cascading links, they grow into hollow cylindrical whiskers.