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1.
MgFe2O4纳米粉体的水热合成及其表征(英)   总被引:3,自引:0,他引:3  
MgFe2O4 nanoparticles were hydrothermally synthesized at 150 ℃ using iron nitrate [Fe(NO3)3·9H2O], magnesium nitrate [Mg(NO3)2·6H2O] and sodium hydroxide (NaOH) as starting materials by carefully controlling the reaction conditions. The influences of several factors such as presence or absence of Na+, molar ratio of Fe3+ / Mg2+, concentration of mental ions, temperature and reaction time on resultant products were investigated in the hydrothermal process. The sample was characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM), and its magnetic properties were measured using vibrating sample magnetometer (VSM).  相似文献   

2.
共沉淀法制备负热膨胀性ZrW2O8粉体及其粒径控制初探   总被引:6,自引:0,他引:6  
Negative thermal expansion (NTE) material ZrW2O8 powders were synthesized using co-precipitation route. The precursor of ZrW2O8 was studied by Thermogravimetric and differential scanning calorimetry (TG-DSC). The structure and morphology of the resulting powders were characterized by Powder X-ray diffraction (XRD) and Scanning electron microscopy (SEM), respectively. The results showed that the samples were single phase of α-ZrW2O8 with regular shape. High temperature X-ray diffraction measurement indicated that the thermal expansion coefficient of ZrW2O8 was -10.35 × 10-6 K-1 in the temperature range from room temperature to 150 ℃, -3.08 ×10-6 K-1 from 200 ℃ to 600 ℃ and the average value was -5.38 × 10-6 K-1. At the same time, polyethylene glycol (PEG) was used as dispersant to primary control the size of ZrW2O8.  相似文献   

3.
水热法制备高纯超细CeO2-ZrO2复合氧化物   总被引:9,自引:0,他引:9  
Superfine composite powders of CeO2-ZrO2 (CZ) and CeO2-ZrO2-La2O3 (CZL) were prepared by hydrothermal method. The effects of pH、temperature and time for hydrothermal process on the performance of the resulting powders were studied. The optimized reaction parameters were on follows: the precursor′s pH≈9.0, hydrothermal temperature of 200 ℃ holding for 2 h. Thermal stable powders with average particle size smaller than 10 nm and specific surface area of 171 m2·g-1 were obtained. A BET specific surface area was still at 44 m2·g-1 after calcination at 1 000 ℃ for 6 hours.  相似文献   

4.
CuInS2 thin films have been prepared by ion layer gas reaction (ILGAR) using C2H5OH as solvent, CuCl and InCl3 as reagents and H2S gas as sulfuration source. The effects of cationic concentrations and numbers of cycle on the properties of CuInS2 film were investigated. The chemical composition, crystalline structure, surface topography, deposited rate, optical and electronic properties of the films were characterized by X-ray diffractrometry (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), ultraviolet-visible spectrometry (UV-Vis) and Hall System. The results show that the crystalline of CuInS2 thin films and the deposition rate have been improved with the increase of cationic concentration, while CuxS segregation phases appear with further increasing cationic concentration. The deposition rate is close to constant as cationic concentration is fixed. CuInS2 thin film derived form lower cationic concentration is uniform, compact and good in adhesion to the substrates. The absorption coefficient of CuInS2 thin films is larger than 104 cm-1, and the band gap Eg is in the range of 1.30~1.40 eV. The dark resisitivity of the thin film decreases from 50 to 10 Ω·cm and the carrier concentration ranges are over 1016 cm-3.  相似文献   

5.
王永在 《无机化学学报》2007,23(6):1055-1058
Nano Mg-Al LDHs were prepared from precursors of MgO and Al(OH)3 using a hydrothermal method in one step and the microstructural features were characterized by powder XRD and SEM. Crystallite sizes were determined by X-ray whole powder pattern fitting method. Effects of synthesis temperatures and alkalinity on phases formation、crystallinity and crystallite sizes of Mg-Al LDHs were investigated. Crystallite form evolved from thin plates to thick plates as the hydrothermal synthesis temperature increases. Layers of interlayer containing OH- and CO32- were distributed orderly or disorderly depending on the the starting alkalinity of the precursors along the c axis resulting in an interstratified Mg-Al LDHs structure.  相似文献   

6.
较为宽松条件下水热合成铁酸铋粉体   总被引:1,自引:0,他引:1       下载免费PDF全文
Bismuth ferrite(BiFeO3) powders were hydrothermally synthesized by using FeCl3·6H2O and BiCl3 as staring materials, NaOH as a mineralizer and NH4Cl as an additive. The results show that pure BiFeO3 powders can be synthesized under loose hydrothermal conditions of reaction temperature ranging from 140 to 230 ℃ and NaOH concentration ranging from 2 mol·L-1 to 5 mol·L-1. Moreover, the morphologies of the products can be controlled by changing the hydrothermal conditions.  相似文献   

7.
Both whisker and nanometer MgSO4·5Mg(OH)2·3H2O(MOS) were prepared by hydrothermal method at 140℃ for different times, using NaOH and MgSO4·7H2O as raw materials. The MgSO4·5Mg(OH)2·3H2O part- icles were characterized by powder X-ray diffraction(XRD),thermal analysis(TGA-DSC), infrared spectroscopy(FT-IR),transmission electron microscopy(SEM) and scanning electron microscopy(TEM). The size distribution in whisker-like and nanocrystalline materials are in the range of 10~50μm and 10~20nm respectively. The whisker MOS is metastable phase in MgSO4-NaOH-H2O system at 140℃,whereas nanometer MOS is stable phase.  相似文献   

8.
The influence of hydrothermal modification on the structure and hydrodenitrogenation (HDN) activity of NiMo/γ-Al2O3catalyst was studied in the range 140~180 ℃. The experimental results indicated that the hydrodenitrogenation reaction rate of pyridine was accelerated using the NiMo/γ-Al2O3catalyst synthesized via hydrothermal route due to the change of the structure, the increase of the amount of Mo and Ni and the rise of the specific surface area. The change of the structure of catalysts was enhanced at higher hydrothermal temperature, producing NiMo/γ-Al2O3catalyst with better HDN activity.  相似文献   

9.
NH4MO(OH)HCO3(M=Al3+, Cr3+) precursors were synthesized by a co-precipition method with the solutions of mixed nitrates as starting materials and ammonium bicarbonate as precipitator. The precursors and powders sintered at various temperatures were characterized by thermogravimetry/differential thermal analysis(TG/DTA), infrared spectroscopy(IR), X-ray diffractormetry(XRD), transmittion electron microscopy(TEM). The luminescent spectra of Cr3+∶Al2O3 nano-powder was measured. The XRD results show that the pure-α-Al2O3 phase can be obtained at 1 200 ℃. TEM analysis indicates that the nano-powders about 20~30 nm are well-dispersed and less-aggregated. Spectral analysis demonstrates that the sample has good photoluminescence.  相似文献   

10.
The organic-inorganic layered compound zinc hydroxide-benzoic acid with basal spacing of 1.92 nm was synthesized hydrothermally using amorphous Zn(OH)2 and benzoic acid at the reaction temperature of 90~130 ℃, the molar ratio of C6H5COOH/Zn(Containing 6 mmol of Zn) of 0.4~0.6, 20 mL H2O and the reaction time of 6 h. The character, structure, particle morphology and chemical composition of the layered compound were characterized by means of XRD, TG-DTA, SEM, TEM and elemental analysis. The results indicate that the layered compound is of plate-like morphology and that with the temperature raising of hydrothermal synthesis, the particle of plate-like piece becomes smaller. The chemical formula of the layered compound could be written as Zn(OH)2-y·(C6H5COO)y·0.3H2O, 0.36≤y≤0.54.  相似文献   

11.
双注-水热法制备高分散氢氧化镁纳米片   总被引:11,自引:0,他引:11       下载免费PDF全文
本工作以氯化镁、氢氧化钠为原料,氯化钠为衬底溶液,探讨了采用双注-水热法制备高分散氢氧化镁纳米片的可行性。结果表明:采用双注方式或提高衬底溶液氯化钠浓度均有利于降低反应体系过饱和度,改善常温产物的结晶性和分散性;对常温合成的氢氧化镁进行水热处理可进一步提高产物的结晶度,形成形貌规则、粒径分布窄、分散良好的氢氧化镁纳米片。  相似文献   

12.
Mono-dispersed Mg(OH)2 nanoflakelets have been prepared with the assistant of 4-(p-nitrophenylazo)resorcinol. The samples were characterized using XRD, TEM, and ED. Electron diffraction analysis showed that single crystalline nanoflakelets were obtained in hydrothermal process, and porous Mg(OH)2 nanosheets were prepared at lower temperature. Nitrogen adsorption isotherms show that the surface area of Mg(OH)2 nanosheets is 129 m2/g. Possible growth mechanism of the nanoflakelets is discussed.  相似文献   

13.
近几年来,氢氧化镁作为一种无机阻燃剂由于其具有制备条件相对温和,生产工艺简单且产品与自然环境友好等特点,在研究及生产活动方面备受关注且得到了长足的发展[1~4].目前采用氢氧化钠法进行反应一水热制备高分散阻燃级氢氧化镁的工艺路线已经比较成熟[5~8].然而,不利的是,氢氧化钠偏高的价格导致了产品的制造成本较高.而采用石灰法制备氢氧化镁阻燃剂具有价格低廉的特点,引起了人们的关注.  相似文献   

14.
Flower-like magnesium hydroxide (Mg(OH)2) nanostructures were synthesized via a simple hydrothermal reaction at relatively low temperature. The Mg(OH)2 nanostructures were then added to acrylonitrile–butadiene–styrene (ABS) and cellulose acetate (CA) polymers. The effect of Mg(OH)2 nanostructures on the thermal stability of the polymeric matrixes has been investigated. The thermal decomposition of the nanocomposites shifts towards higher temperature in the presence of the Mg(OH)2. The enhancement of thermal stability of nanocomposites is due to endothermically decomposition of magnesium hydroxide that releases of water and dilutes combustible gases. Nanostructures and nanocomposites were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), Fourier transform infrared (FT-IR) spectroscopy, thermogravimetric analysis (TGA), differential thermal analysis (DTA), UL-94 test and limiting oxygen index (LOI) analysis.  相似文献   

15.
氢氧化镁的结晶习性研究   总被引:41,自引:4,他引:37       下载免费PDF全文
本文用负离子配位多面体模型探讨了NaOH水热介质中Mg(OH)2晶体的结晶习性。提出了Mg(OH)2的水热改性属溶解-结晶机制、生长基元为Mg(OH)6^4-八面体的观点。Mg(OH)2-NaOH-H2O体系高温热力学计算和电阻在线检测结果间接验证了生长基元论点。理论推导表明:Mg(OH)6^4-八面体的共棱连接方式决定了Mg(OH)2的结晶习性。  相似文献   

16.
β-Co(OH)2 and Mg(OH)2 nanoplates were synthesized via a facile template-free hydrothermal approach.The different conditions of preparation and catalytic properties of the products were studied and discussed.The products were characterized by X-ray diffraction,transmission electron microscopy,scanning electron microscopy,selected area electron diffraction(SAED),and gas chromatograph.  相似文献   

17.
The synthesis of Mg(OH)2 one-dimensional (1D) nanostructures was systematically investigated in different solvents at various temperatures with Mg10OH18Cl2·5H2O nanowires as source materials. The results showed that the characters of the products, such as crystal size, shape, and structure, were strongly influenced by the solvent and temperature during the solvothermal process. 1D nanotubes of Mg(OH)2, with 80-300 nm outer diameter, 30-80 nm wall thickness, and several tens of micrometers in length were obtained by choosing bidentate ligand solvents such as ethylenediamine and 1,6-diaminohexane as the reaction solvent. But when using monodentate ligand pyridine as the reaction solvent, the obtained samples showed nanorods morphology. The Mg(OH)2 thus produced was analyzed by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), high-resolution electron microscopy (HRTEM), and selected-area electron diffraction (SAED). The possible growth mechanism of the 1D nanostructure Mg(OH)2 was discussed.  相似文献   

18.
以β-Ni0.9Co0.05Mn0.025Mg0.025(OH)2和LiOH.H2O为原料通过高温固相法合成了球形LiNi0.9Co0.05Mn0.025Mg0.025O2。采用热重-差热分析了反应过程,采用X射线衍射和扫描电镜对粉末的结构和形貌进行了表征。采用充放电测试和循环伏安测试对材料电化学性能进行了研究。结果表明:750℃煅烧12 h合成的LiNi0.9Co0.05Mn0.025Mg0.025O2为Li原子混排较少的良好层状结构,二次颗粒尺寸在15μm左右,且具有最高的放电比容量和良好的循环性能,在0.2C,2.8~4.3 V的条件下,首次放电比容量达207 mAh.g-1,40次循环后容量保持率为92.5%。  相似文献   

19.
Magnesium hydroxide [Mg(OH)2] nanocrystals with excellent dispersity and good crystallinity were efficiently synthesized through the ultrasonic and hydrothermal synergetic effect. The morphology, structure, and thermochemistry of Mg(OH)2 nanocrystals were researched by TEM, XRD, FT-IR, and DTA, respectively. The mechanism of ultrasonic–hydrothermal synergistic effect was discussed. In addition, Mg(OH)2 nanocrystals were added into polypropylene (PP) to form composite materials, and the mechanical properties of Mg(OH)2–PP composites were investigated. Compared with the other two Mg(OH)2 PP composites, the Mg(OH)2–PP composite had the best mechanical property when the Mg(OH)2 was synthesized by ultrasonic–hydrothermal route.  相似文献   

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