EDTA辅助水热法制备性能优异的棒状LiFePO4/C材料

以乙二胺四乙酸为配位剂采用水热法制备了棒状LiFePO₄/C材料。采用X射线衍射、扫描电镜、透射电镜、循环伏安、交流阻抗和恒电流充放电测试等对材料进行表征。结果表明:乙二胺四乙酸对材料的形貌和电性能均有很大影响。通过加入乙二胺四乙酸, 材料的形貌由不规则的颗粒变为棒状的颗粒且颗粒的厚度由140~200 nm减少至40~90 nm, 材料的表面包覆约3.5 nm的均匀碳层, 且该材料极化较小且界面阻抗较低。0.1C放电比容量为167 mAh·g^-1(接近理论容量170 mAh·g^-1)。     

Thermal decomposition of ammonium copper chromate: effect of the addition of barium

The influence of the addition of barium (as barium chromate) to ammonium copper chromate on its thermal decomposition has been investigated by TG, DTG and DTA in the temperature range 303–1273 K. The solid products formed in the decomposition at different temperatures were characterised by X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy and also by measuring their specific surface area. The addition of BaCrO₄ at different concentrations (0–19.8%) was found not to change the general trend in the decomposition of ammonium copper chromate (which occurs in four distinct steps), except small changes in the temperature corresponding to DTG and DTA peaks. However, the sintering (or crystal growth) of the solid product is largely reduced by the presence of BaCrO₄.     

Influence of surfactants on the morphologies of CaCO3 by carbonation route with compressed CO2

Three surfactants, sodium dodecyl sulfate (SDS), cetyltrimethylammonium bromide (CTAB) and polyoxyethylene-80-sorbitan monooleate (Tween 80), were used to control the growth of CaCO₃ crystals by carbonation route using Ca(OH)₂ and compressed CO₂. The obtained CaCO₃ particles were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD) techniques. The effects of surfactants on the morphology of the particles were studied. It was demonstrated that Tween 80 and SDS have obvious effect on the morphology of CaCO₃ particles, while CTAB does not affect morphology considerably. The possible mechanism has been discussed on the basis of the binding of the surfactants to the certain face of the crystals.     

超声化学法制备不同形貌的CaF2微米晶

采用超声化学法,以CaCl2与不同氟源(NaBF4、K2SiF6)在溶液中反应,制得了不同形貌的CaF2微米晶(立方体、花状、多面体)。用XRD、SEM及TEM对产物晶相及形貌进行了表征。XRD结果显示所有产物均为结晶良好的立方相CaF2。SEM及TEM结果表明由NaBF4制得的产物形貌为均匀的立方体微米晶,而由K2SiF6制得的产物为多面体。在添加配体Na2EDTA的情况下,由NaBF4得到的产物为纳米片组成的花状结构。本文详细讨论了氟源种类、反应物比例、配体等反应参数对产物CaF2形貌的影响,并提出了可能的反应机理。     

Hydrothermal synthesis of lindgrenite with a hollow and prickly sphere-like architecture

Lindgrenite [Cu₃(OH)₂(MoO₄)₂] with a hollow and prickly sphere-like architecture has been synthesized via a simple and mild hydrothermal route in the absence of any external inorganic additives or organic structure-directing templates. The hierarchical lindgrenite particles are hollow and prickly spheres, which are comprised of numerous small crystal strips that are aligned perpendicularly to the spherical surface. Two factors are important for the formation of hollow and prickly architecture in the present process. One is the general phenomenon of Ostwald ripening in solution, which can be responsible for the hollow structure; the other is that lindgrenite crystals have a rhombic growth habit, which plays an important role in the formation of prickly surface. Furthermore, Cu₃Mo₂O₉ with the similar size and morphology can be easily obtained by a simple thermal treatment of the as-prepared lindgrenite in air atmosphere.     

Crystal growth of CaCO3 induced by monomethylitaconate grafted polymethylsiloxane

We report the preparation of a new monomethylitaconate grafted polymethylsiloxane (CO₂H-PMS) copolymer and its effect as template for crystal growth of CaCO₃. The in vitro crystallization of CaCO₃ was carried out using the gas diffusion method at different pH values at room temperature for 24 h. The CO₂H-PMS was prepared using polydimethylsiloxane-co-methylhydrogensiloxane (PDMS-co-PHMS), obtained through cationic ring opening polymerization, from cyclic monomers and monomethyltaconate (MMI) via hydrosilylation reactions with platinum complex as catalyst. FTIR results are in an agreement with the proposed template structure and confirmed that the hydrosilylation was complete. Experimental results from pH values and SEM analysis showed that the carboxylate groups of CO₂H-PMS alter the nucleation, growth and morphology of CaCO₃ crystals. SEM revealed single-truncated (ca. 5 μm) modified at pH 7-9, aggregated-modified (ca. 20 μm) at pH 10-11, and donut-shaped crystals at pH 12. These morphologies reflect the electrostatic interaction of carboxylic moieties with Ca²⁺ modulated by CO₂H-PMS adsorbed onto the CaCO₃ particles. EDS confirmed the presence of Si atoms on the crystals surface. XRD analysis showed the existence of only two polymorphs: calcite and vaterite revealing a selective control of CaCO₃ polymorphisms. In summary, the use of grafted polymethylsiloxane template offer a good alternative for polymer controlled crystallization and a convenient approach for understanding the biomineralization process useful for the design of novel materials.     

Synthesis and spectroscopic characterization of Mn(II) doped organic amine templated chlorocadmiumphosphate CdHPO4Cl · [H3N(CH2)6NH3]0.5 crystals

Chlorocadmiumphosphate CdHPO₄Cl?·?[H₃N(CH₂)₆NH₃]_0.5 crystals doped with Mn(II) are grown at room temperature via organic amine template method and characterized by spectroscopic techniques to obtain information on the nature of the incorporated Mn(II). Powder X-ray diffraction patterns of the sample are indexed to monoclinic cell and average crystalline size is found to be around 55?nm. The optical absorption spectrum exhibits various bands which are characteristic of Mn(II) in distorted octahedral site symmetry, confirmed by characteristic resonance signal at g?=?2.018 observed in the EPR spectrum. Fourier transform infrared spectrum shows the specific vibrations of phosphate and organic molecules. Thermal curves indicate that the crystal is stable at 307°C; above this temperature crystal structure disintegrates due to removal of the organic amine template.     

Morphological control of calcium oxalate particles in the presence of poly-(styrene-alt-maleic acid)

Calcium oxalate (CaOx) particles exhibiting different shapes and phase structures were fabricated by a simple precipitation reaction of sodium oxalate with calcium chloride in the absence and presence of poly-(styrene-alt-maleic acid) (PSMA) as a crystal modifier at room temperature. The as-obtained products were characterized with scanning electron microscopy (SEM) and X-ray diffraction (XRD). The effects of reaction conditions including pH, [Ca²⁺]/[C₂O₄²⁻] ratio and concentration of PSMA and CaC₂O₄ on the crystal forms and morphologies of the as-obtained calcium oxalate were investigated. The results show that various crystal morphologies of calcium oxalate, such as parallelograms, plates, spheres, bipyramids etc. can be obtained depending on the experimental conditions. Higher polymer concentration favors formation of the metastable calcium oxalate dihydrate (COD) crystals. Lower pH is beneficial to the formation of plate-like CaOx crystals. Especially, the monodispersed parallelogram-like CaOx crystals can be produced by PSMA as an additive at pH 2. PSMA may act as a good inhibitor for urolithiasis since it induces the formation of COD and reduces the particle size of CaOx. This research may provide new insight into the morphological control of CaOx particles and the prevention of urolithiasis.     

针状纳米SrFe12O19的溶胶-凝胶法制备及磁性研究

采用柠檬酸-EDTA的联合络合溶胶-凝胶法制得了针状纳米锶铁氧体磁性微粒。利用XRD对样品的物相进行分析,利用TEM对样品形貌和粒径进行表征,并利用振荡样品磁强计(VSM)对样品进行了磁性能研究。结果表明,相对于柠檬酸法制备的纯锶铁氧体微粒,EDTA加入后制备的SrFe₁₂O₁₉微粒仍保持六方磁铅石型结构,但是粒径减小,形貌向一维发展,且内禀矫顽力H_c显著提高。并直接对凝胶加热,使其发生自蔓延燃烧,省去了凝胶的干燥过程,制备周期缩短1/4以上,同时自蔓延燃烧使SrFe₁₂O₁₉的内禀矫顽力提高10%左右,通过洗涤前驱体使得SrFe₁₂O₁₉纯度得到提高,进而使比剩余磁化强度和比饱和磁化强度提高20%左右,最终制得了粒径为30 nm,长径比为5∶1,内禀矫顽力、比饱和磁化强度与比剩余磁化强度分别为6 446.9 Oe、68.9 emu·g^-1和40.2 emu·g^-1的针状纳米SrFe₁₂O₁₉。     

水热条件下金红石纳米晶在离子液体[C12mim]Cl中的制备

在室温离子液体1-十二烷基-3-甲基氯化咪唑([C12mim]Cl)中,通过水热法制备了具有单晶结构的金红石纳米材料。采用X射线衍射、扫描电镜和透射电镜对样品进行了表征,结果显示所得样品为纯金红石相,形貌呈棒状。扫描电镜和透射电镜图样显示金红石纳米棒的直径约为15 nm,长度在10～100 nm之间。高分辨投射电镜图样显示金红石纳米棒为单晶结构,并沿c轴方向生长。实验结果表明离子液体[C12mim]Cl中的Cl-有利于金红石相生成,[C12mim]+起到了模板剂的作用并提高了金红石纳米棒的结晶度。     

Synthesis of large surface area nano-sized BiVO4 by an EDTA-modified hydrothermal process and its enhanced visible photocatalytic activity

In this work, monoclinic scheelite-type BiVO₄ nanoparticle with large surface area has been successfully synthesized, using Bi(NO₃)₃ and NH₄VO₃ as raw materials, through a hydrothermal process in the presence of ethylene diamine tetraacetic acid (EDTA). It is demonstrated that the nanoparticle size of as-prepared BiVO₄ becomes small by decreasing hydrothermal temperature, shortening hydrothermal reaction time and increasing EDTA amount used. The resulting BiVO₄ nanoparticle with large surface area exhibits a good photocatalytic performance for degrading phenol solution as a model organic pollutant under visible illumination. The key of this method is the chelating role of EDTA group in the synthetic process that it can greatly control the concentration of Bi³⁺, leading to the growth inhibition of BiVO₄ crystallite. The work provides a route for the synthesis of Bi-containing nano-sized composite oxides with large surface area.     

Facile solvothermal synthesis of highly active monoclinic scheelite BiVO4 for photocatalytic degradation of methylene blue under white LED light irradiation

In this study, BiVO₄ was successfully synthesized via the solvothermal process using a solvent mixture of ethylene glycol and water under different synthesis conditions of temperature and pH. Physicochemical properties such as crystal phase, morphology, and optical absorption of the as-synthesized BiVO₄ samples were characterized by X-ray diffraction (XRD), Raman spectra, field emission scanning electron microscopy (FE-SEM), and ultraviolet–visible diffraction reflection spectroscopy (UV–vis DRS). The XRD analysis showed that different synthesis conditions of temperature and pH significantly affected the growth of monoclinic BiVO₄ crystals oriented along (0 4 0) facets. Form SEM results, the synthesis conditions, including pH and temperature, have a great effect on the morphology of monoclinic structured BiVO₄. As the pH value increases in the range of 0–9 and temperature increases from 80 °C to 180 °C, the morphology of BiVO₄ changed from peanut-, rod-, and leaf-like shapes. The photocatalytic activities of as-synthesized BiVO₄ photocatalysts were evaluated by the photodegradation of methylene blue (MB) dye under irradiation of white LED light. We have found that by using appropriate synthesis conditions (the synthesis temperature of 140 °C and the synthesis pH of 7) the BiVO₄ exhibited high photocatalytic efficiency for MB degradation (about 82.30% after 180 min of irradiation). This result is due to the development of the BiVO₄ crystals oriented along (0 4 0) facets with an increase in the intensity ratio of I_(0 4 0)/I_(1 2 1). The growth of BiVO₄ crystals oriented along (0 4 0) facets may be beneficial to enhance the photocatalytic activity of monoclinic scheelite BiVO₄.     

铁酸铋粉体:硝酸钾辅助水热合成的形貌调控及可见光催化性能(英文)

利用硝酸钾作为辅助矿化剂,采用水热法合成了不同尺寸和形貌的铁酸铋粉体,探索了硝酸钾的加入量对产物的尺寸和形貌的影响。采用X射线衍射、扫描电镜和透射电镜以及漫反射光谱对制备的铁酸铋粉体的相结构、微观形貌以及光吸收特性进行了表征。结果显示,随着尺寸的减小,粉体的吸收带边发生蓝移。可见光降解刚果红实验表明,粒径小的铁酸铋纳米粉体颗粒具有更好的可见光催化活性。     

Facile Fabrication of Nanorod‐Assembled Fluorine‐Substituted Hydroxyapatite (FHA) Microspheres

Nanorod‐assembled FHA microspheres with different F contents were for the first time prepared through a facile one‐step hydrothermal method. The effect of the reaction time and pH value of reaction solutions on the FHA morphology was investigated to elucidate the self‐assembly process of FHA microspheres. The results showed pH values had significant effect on the morphology of the formed FHA crystals, which were self‐assembled into sphere‐like sturctures at high pH conditions and rod‐like structures at low pH values. The results suggested that formation of FHA crystals with varied morphology may be directly related to Ca²⁺ release kinetics from EDTA‐Ca‐Na₂ at different pH conditions. Furthermore, it was found that the chemical stability of FHA microspheres was dependent on the F content in the materials, and high F contents in FHA microspheres lead to improved chemical stability. These results suggest that the prepared self‐assembled FHA microspheres may be used for teeth substitution materials due to their unique hierarchical structures and controllable chemical stability.     

Synthesis,Properties, and Evolution Mechanism of Morphology Tunable InPO4 Crystals

In the synthesis of InPO₄ crystals, using F127 [(EO)₁₀₆(PO)₇₀(EO)₁₀₆] as a structure‐directing template, a morphology tunable progress was observed during the crystal evolution. By verifying the initial pH from 1.0 to 12.0, the morphology is evolved from single crystal, through sub‐micro crystallites, and finally to crystalline nanoparticles. The most influential factors in the morphology evolution are the initial pH level, the participation of surfactant‐template F127, and the change in pH during the reaction.     

Polyepoxysuccinic acid with hyper-branched structure as an environmentally friendly scale inhibitor and its scale inhibition mechanism

In order to improve the scale inhibition efficiency of existing polyepoxysuccinic acid (PESA) and to study the impact of their molecular structure on scale inhibition efficiency, a series of PESA with linear and hyper-branched structure have been designed and synthesized through co-polymerization reaction with glycidyl and epoxy succinate. The scale inhibition behavior of PESA with linear and hyper-branched structure against CaCO₃ and CaSO₄ scales was evaluated using static scale inhibition method, and their ability to retard deposition of CaCO₃ was also examined. The experimental results showed that, for CaCO₃ and CaSO₄, the PESA with hyper-branched structure provides a scale inhibiting efficiency as high as 95.9% and 94.3%, respectively, at an inhibitor concentration of 15?mg/L. In addition, the processes of crystal nucleation, growth and crystal morphology have been analyzed. The experimental results show that the PESA with hyper-branched structure not only prolongs the induction period of CaCO₃ crystal nucleation, but also reduces the number of crystal nuclei and changes the size and morphology of the CaCO₃ crystal. Moreover, the FTIR, SEM and XRD analyses showed that the PESA with hyper-branched structure can induce the irregularity of growing CaCO₃ crystal, destroy the formation of crystals and change the polymorphs of calcium scale crystal. This conclusion indicates that the prepared PESA with hyper-branched structure has great potential for applying in the treatment of industrial water.     

超声化学法制备BaF_2纳米粒子及纳米方块

<正>0引言BaF2的用途非常广泛,可用于光学玻璃、陶瓷色料、玻璃光导纤维、激光发生器、助熔剂及防腐剂等。BaF2是最快的闪烁体,在核物理和核技术中用来检测γ射线和带电粒子[1]。将掺杂稀土金属的纳米BaF2粒子嵌入有机或玻璃基体以发挥其发光性能的研究越来越引起重视[2]。碱土氟化物和许多半导体的晶格匹配性良好,可以用不同碱土氟化物层来连接晶格常数不同的半导体[3]。     

可控粒径纳米Fe_3O_4的制备及其磁性研究

本文用空气氧化法,在可见光作用下,添加配合剂(EDTA、柠檬酸、酒石酸、谷氨酸)在室温进行了不同粒径纳米Fe3O4的制备及其磁性能研究。结果表明:在可见光作用下,随EDTA、柠檬酸、酒石酸、谷氨酸等配合剂的添加,得到纳米Fe3O4的粒径有所减小、分散性有所提高;配合剂及可见光共存时,体系反应速率得到提高,高的反应速率使纳米Fe3O4晶粒减小;控制适当的光照度和添加剂的量,室温可得到11.8~29.6nm的Fe3O4颗粒。不同粒径纳米Fe3O4分别呈现出超顺磁性、铁磁性特征。     

Synthesis, characterization and photocatalytic properties of novel zinc germanate nano-materials

We report the first instance of a hydrothermal synthesis of zinc germanate (Zn₂GeO₄) nano-materials having a variety of morphologies and photochemical properties in surfactant, template and catalyst-free conditions. A systematic variation of synthesis conditions and detailed characterization using X-ray diffraction, ultraviolet-visible diffuse reflectance spectroscopy, Raman spectroscopy, electron microscopy, X-ray photoelectron spectroscopy and small angle X-ray scattering led to a better understanding of the growth of these particles from solution. At 140 °C, the zinc germanate particle morphology changes with pH from flower-shaped at pH 6.0, to poly-disperse nano-rods at pH 10 when the Zn to Ge ratio in the synthesis solution is 2. When the Zn to Ge ratio is reduced to 1.25, mono-disperse nano-rods could be prepared at pH 7.5. Nanorod formation is also independent of the addition of cetyltrimethylammonium bromide (CTAB), in contrast to previous reports. Photocatalytic tests show that Zn₂GeO₄ nano-rods (by weight) and flower shaped (by surface area) are the most active for methylene blue dye degradation among the synthesized zinc germanate materials.