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1.
Long Chen Yuhua Shen Anjian Xie Fangzhi Huang Shikuo Li Qingfeng Zhang 《Crystal Research and Technology》2008,43(8):797-800
Unusual rhombohedral strontium carbonate (SrCO3) aggregates have been synthesized in situ from strontium nitrate by the slow release of carbon dioxide by alkaline hydrolysis of diethyl carbonate at the water/hexamethylene interface in the presence of cetyltrimethylammonium bromide (CTAB). Transmission electron microscopy, Fourier transform infrared spectroscopy and X‐ray powder diffractometry were used to characterize the products. The results indicate that rhombohedral SrCO3 aggregates are obtained with weaker crystallinity and sizes of several micrometers. The possible formation mechanism of the SrCO3 aggregates at the interface is discussed, which can be interpreted by particle‐aggregation based non‐classical crystallization laws. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
2.
Long Chen Fengkai Hu Quan Zhou Jinyu Sun Hui Zhang 《Crystal Research and Technology》2009,44(12):1289-1292
In this paper, crystal growth of calcium carbonate (CaCO3) in the presence of biomolecules of lotus root was investigated. Scanning electron microscopy, Fourier transform infrared spectroscopy and X‐ray powder diffractometry were used to characterize the products. The results indicate that calcite spherical particles were constructed from small rhombohedral subunits. Similar CaCO3 crystals were also gained when crystal growth of CaCO3 in aqueous solution containing extracts of lotus root was performed, suggesting that the soluble biomolecules of lotus root play a crucial role in directing the formation of hierarchical calcite spherical particles. The possible formation mechanism of the CaCO3 crystals by using lotus root is also discussed, which can be interpreted by particle‐aggregation based non‐classical crystallization laws. The biomolecules of lotus root might induce and control the nucleation and growth of calcium carbonate crystals. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
3.
S. Ouhenia D. Chateigner M.A. Belkhir E. Guilmeau C. Krauss 《Journal of Crystal Growth》2008,310(11):2832-2841
Calcium carbonate precipitates are prepared from a solution of CaCl2 and K2CO3 in the presence of polyacrilic acid. The effect of polyacrilic acid incorporation in the [25–80 °C] temperature range on crystal morphologies and CaCO3 precipitated polymorph concentrations are investigated using scanning electron microscopy and X-ray diffraction quantitative microstructural and phase analysis. Large changes in morphology and phase proportions are observed in the presence of polyacrylic acid, which strongly depend on the solution temperature. While crystallization of vaterite is favoured in the presence of polyacrilic acid up to 50 °C, it is largely destabilized at higher temperatures. Our process also enables the elaboration of particles in the range 10–20 nm. 相似文献
4.
Xiaoyun Xu Qiongyu Lai Yan Zhao Yanjing Hao Hongmei Zeng Ling Wang 《Crystal Research and Technology》2010,45(7):712-716
The dumbbell‐like calcium carbonate (CaCO3) crystals were synthesized in the presence of trisodium citrate. Different morphologies were obtained by changing the reaction temperature and the trisodium citrate concentration. The obtained samples were characterized by means of X‐ray diffraction (XRD) and scanning electron microscopy (SEM). The results showed that the morphology of CaCO3 crystals was markedly affected by the reaction temperature and citrate anion concentration. The possible growth mechanism of CaCO3 crystals was proposed. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
5.
绒毛球状碳酸锶的沉淀法制备与表征 总被引:1,自引:0,他引:1
以柠檬酸三钠为晶形控制剂,采用简单沉淀法合成了绒毛球状SrCO3晶体.用扫描电子显微镜(SEM)、X射线衍射仪(XRD)、傅里叶红外光谱仪(FTIR)、热重分析仪(TG)、透射电镜(TEM)和能谱仪(EDX)等对样品的结构和形貌进行了表征.结果表明,绒毛球状SrCO3的主体结构为微米级实心球,实心球壳表面被一层稠密的粒径为5~15 nm、长度为100 ~ 150 nm的毛发状晶体所覆盖;机理分析认为绒毛球状SrCO3的形成可以用“棒状-束状-哑铃形-球形”的生长机理(RBDS)进行解释. 相似文献
6.
Xiaohui Zhang Fengwen Yan Cunyue Guo Fengbo Li Guochang Chen Zhijun Huang Guoqing Yuan 《Crystal Research and Technology》2011,46(7):664-668
Crystalline calcium carbonate with randomly dispersed porous structure was prepared through co‐ crystallization with calcium peroxide and the following template elimination by a post heating treatment and washing with water. The artificial CaCO3 possess abundant macro‐mesopores structures and high surface area. This approach may open a new general route for the preparation of crystals with high porosity and structure specialty. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
7.
AbstractThe effect of Mg2+ on the crystallization of precipitated calcium carbonate (PCC) via a bubbling carbonation method and the mechanism of eliminating its influence by glucose were investigated. The polymorph and morphology of crystals were characterized by field emission-scanning electron microscopy, X-ray diffraction, and Fourier transform infrared spectroscopy. These results demonstrated that Mg2+ and Mg/Ca molar ratio played significant roles on the morphology of PCC. When the Mg/Ca molar ratio was below 0.5, only spindle-like calcite formed. The rod-like aragonite started to form when the ratio was 0.6. As the ratio increased, the amount of aragonite increased and the length of rod-like aragonite became longer. Notably, the effect of Mg2+ could be eliminated efficiently when the 1.5?wt% glucose was added into the carbonation system, in which system, the PCC crystals were all spindle-like calcite. Furthermore, the mechanism of the glucose to eliminate the influence of Mg2+ on PCC crystallization was proposed. 相似文献
8.
Crystallization habit of calcium carbonate in presence of sodium dodecyl sulfate and/or polypyrrolidone 总被引:7,自引:0,他引:7
The synthesis of calcium carbonate (CaCO3) crystals from aqueous solutions containing sodium dodecyl sulfate (SDS), poly(N-vinyl-1-pyrrolidone) (PVP) or SDS/PVP complexes has been performed through a slow titration method. It was found that aragonite and calcite coexisted in the prepared crystals. The formation of aragonite in the precipitation systems without magnesium ions indicates that at ambient temperature ca. 26.0°C, initially formed amorphous CaCO3 could also transfer into aragonite in the sedimentary phase, which indicates the controlling factor of organic additives in the nucleation and growth process of CaCO3 crystals. The appearance of hexagonal crystals in the suspensible phase confirmed the hexagonal crystallization cell of vaterite, and revealed the colloidal-dispersion function of the SDS/PVP complex in the crystallization process of CaCO3. 相似文献
9.
Uniform magnesium oxysulfate (5Mg(OH)2·MgSO4·3H2O) whiskers with a length of 10‐15 µm and a diameter of 0.4‐1.0 µm were synthesized in the presence of sodium dodecyl benzene sulfonate (Na‐SO3‐C6H4‐C12H25) at 200°C for 1 h, using MgSO4·7H2O and NaOH as the reactants. Mg(OH)2 precursor with poor crystallization and small crystal size was formed owing to the adsorption of sodium dodecyl benzene sulfonate on the Mg(OH)2 surface. The quick dissolution of Mg(OH)2 precursor in the subsequent hydrothermal reaction inhibited the occurrence of the sector‐like byproduct and promoted the formation of magnesium oxysulfate whiskers with uniform morphology. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
10.
11.
Sheming Lu Shoubo Qin Yanxiong Ke Jianmin Li Hongxia Pei Shuxi Zhou Xintao Wu Wenxin Du 《Crystal Research and Technology》2004,39(1):89-93
Two new inorganic‐organic complexes, namely, [Ag2(hmt)2]Cr2O7·H2O ( 1 ) and [Ag(hmt)(tar)0.5]·H2O ( 2 ), (hmt = hexamethylenetetramine, Tar = tartarate,), have been synthesized in H2O/CH3CN solvent at room temperature. Both molecules have the common [Ag3hmt3]3+ layers. Compound 1 is a two‐dimensional structure, and Complex 2 shows three‐dimensional topology. In complex 2 , the tartarate molecules are connected with adjacent layers to form parallelogram pores of 18.55×7.44 Å, which are occupied by two water molecules. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
12.
F. Jones A. Oliviera G.M. Parkinson A.L. Rohl A. Stanley T. Upson 《Journal of Crystal Growth》2004,270(3-4):593-603
Calcium ions have been implicated in changing the precipitation of barium sulfate when organic additives are present, although whether it inhibits or promotes nucleation and/or growth has been disputed in the literature. We conducted a thorough investigation into the effect of calcium when additives are present and show that calcium cations do indeed promote nucleation of barium sulfate particles when compared to the appropriate control. This result is independent of the analytical method (conductivity or turbidity) used to assess precipitation. The nucleation promotion produces no change in the crystal morphology, thus morphology is not always a good indicator of nucleation or growth behavior. The extent of nucleation promotion depends on the functional group of the additive. 相似文献
13.
The influence of static magnetic field of strength 0.75 T on the nucleation of calcium carbonate crystals has been investigated. Particle size analysis shows that magnetic field can cause marked difference in distribution. One of the major impacts of magnetic exposure is the increase in number of the critical nuclei formed. Also, magnetic field promotes the formation of parallelepipedic calcite crystals and the dissolution of the smaller crystals by Ostwald ripening mechanism. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
14.
M. Fernandes F. A. Almeida Paz J. F. Mano V. de Zea Bermudez 《Crystal Research and Technology》2014,49(6):418-430
The influence of myristyl alcohol (CH3(CH2)13OH), cetyl alcohol (CH3(CH2)15OH) and behenyl alcohol (CH3(CH2)21OH) on the structure, morphology, size and surface properties of calcium carbonate (CaCO3) has been investigated. Changes in the nature of the washing solvent, in the CnOH/Ca2+ and CO32−/Ca2+ molar ratios and in temperature have been also evaluated. The sole polymorph produced was rhombohedral calcite. At room temperature, while microspheres composed of submicrocubes were produced at a high molar ratio CO32−/Ca2+ and low CH3(CH2)15OH concentration, a stoichiometric molar ratio CO32−/Ca2+ and high CH3(CH2)15OH concentration induced the formation of microcubes and microboxes. In the presence of this alkanol (12 % molar) a significant enhancement of the water contact angle (ca. 40 °) resulted in a sample obtained with a stoichiometric CO32−/Ca2+ ratio. These results emphasize the key role played by the three non‐ionic surfactants in the formation of materials with variable crystal shape and wettability and thus technological interest for a range of applications. 相似文献
15.
Jingcai Zhao Xingfu Song Yuzhu Sun Bo Chen Jianguo Yu 《Crystal Research and Technology》2015,50(4):277-283
Batch reactive crystallization of calcium carbonate (CaCO3) from ammonium carbonate ((NH4)2CO3) and calcium sulfate (CaSO4) was investigated in the presence of magnesium (Mg2+) ions. It was observed that Mg2+ ions partly inhibited the conversion of CaSO4 into CaCO3. When the content of Mg2+ was less than 2%, the reduction in conversion rate of CaSO4 was less than 2%, and the effect of Mg2+ ions could be ignored. Effect of impurity on crystallization kinetics of CaCO3, including the growth rate and nucleation rate, was investigated. The results revealed that when Mg2+ ions content was less than 1%, Mg2+ could promote the growth of CaCO3 and inhibit the nucleation process, which was favorable for the filtration of CaCO3.When the content of Mg2+ ions was greater than 1%, Mg2+ inhibited the growth of CaCO3, which resulted in explosion nucleation and led to a large number of particles in the solution, which was unfavorable for the filtration of CaCO3. Based on the Bransom model, the particle size distribution equations of CaCO3 were established. X‐ray diffraction patterns and scanning electron microscopy images exhibited the existence of spherical vaterite of CaCO3 due to the reaction of CaSO4 with (NH4)2CO3 under the effect of Mg2+ ions, which was inconsistent with the results reported in the literatures. 相似文献
16.
Growth of single crystals of the title compound Sr(C4H4O5).3H2O is achieved using the gel diffusion technique. Multifaceted single crystals of size up to 4x3x3 mm3 are obtained. X‐Ray Diffraction (XRD) pattern of the grown crystal and the Fourier Transform Infra‐Red (FTIR) spectrum in the range 400‐4000 cm‐1 are recorded. The vibrational bands corresponding to different functional groups are assigned. Thermal behavior of the material is investigated using Thermo Gravimetry (TG) and Differential Thermal Analysis (DTA). Thermal studies are indicative of a five‐stage decomposition scheme. © 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim 相似文献
17.
Y.R. Somarathna M.M.M.G.P.G. Mantilaka D.G.G.P. Karunaratne R.M.G. Rajapakse H.M.T.G.A. Pitawala K.G. Upul Wijayantha 《Crystal Research and Technology》2016,51(3):207-214
This research paper describes the synthesis of nano‐ and micro‐structures of high purity precipitated calcium carbonate (PCC) on poly(ethylene glycol)(PEG) templates for broad‐range industrial applications, using readily available and cheap impure dolomitic marbles. In the method, calcium components of impure dolomitic marbles are extracted as calcium sucrate which is then bubbled with carbon dioxide gas using a carbonation column in the presence of PEG. The effects of concentration of PEG, pH of calcium sucrate solution and temperature on the final yield, morphology and polymorphism of PCC have been studied. Vaterite and calcite are the crystalline forms of calcium carbonate found in final PCC products. The vaterite is observed as hollow spheres with particle diameter of 1.5‐2 μm which is formed by aggregation of vaterite nanoparticles with particle size of 20 nm on PEG templates. Optimum conditions for the highest PCC yield of 79.94% are 0.4 mol dm−3 of PEG, pH of 6.5 and temperature of 80 °C. The purity of PCC products is about 99%. Therefore, the synthesized PCC products are of required purity and quality for industrial applications. 相似文献
18.
Shuxia Li Li YuFei Geng Lijuan ShiLiqiang Zheng Shiling Yuan 《Journal of Crystal Growth》2010,312(10):1766-1773
Nano- and micro-sized calcium carbonate (CaCO3) with various morphologies including multi-petal-flower-shaped, multi-step-cube-shaped, coral-shaped, dendrite-shaped and multi-antenna-shaped was successfully prepared using dodecyltrimethylammonium bromide (DTAB) micellar vevulsant. The effects of temperature, pH and the concentration of DTAB micellar solution on the morphology and crystalline form of CaCO3 were systematically investigated. The prepared CaCO3 was characterized by Scanning Electron Microscope (SEM), Transmission Electron Microscopy (TEM), X-ray Diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FTIR). The concentration of DTAB micelle, pH and reaction temperature are found to play crucial roles in the morphology, size and crystalline form of the final products. On the base of the characterizations, a possible self-assembled mechanism was proposed. The novel multi-petal-flower-shaped and multi-antenna-shaped CaCO3 may have some unique properties and potential applications in the future. 相似文献
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20.
In this study, a biomimetic template was prepared and applied for growing calcium carbonate (CaCO3) nanorods whose shape and polymorphism were controlled. A biomimetic template was prepared by adsorbing catalytic dipeptides into the pores of an anodic aluminum oxide (AAO) membrane. Using this peptide-adsorbed template, mineralization and aggregation of CaCO3 was carried out to form large nanorods in the pores. The nanorods were aragonite and had a structure similar to nanoneedle assembly. This aragonite nanorod formation was driven by both the AAO template and catalytic function of dipeptides. The AAO membrane pores promoted generation of aragonite polymorph and guided nanorod formation by guiding the nanorod growth. The catalytic dipeptides promoted the aggregation and further dehydration of calcium species to form large nanorods. Functions of the AAO template and catalytic dipeptides were verified through several control experiments. This biomimetic approach makes possible the production of functional inorganic materials with controlled shapes and crystalline structures. 相似文献