检索结果-南通市图书馆

Particuology 2022年第6期20卷 93-104页

作者： Jinbo Ouyang Xiaohong Xing Jian Chen Limin Zhou Zhirong Liu Jerry Y.Y.Heng Jiangxi Province Key Laboratory of Polymer Micro/Nano Manufacturing and Devices East China University of TechnologyNanchang 330013China Department of Chemical Engineering Imperial College LondonSouth Kensington CampusLondon SW72AZUK

Swift cooling crystallization of vanillin was investigated in water,ethanol,isopropanol and ethyl acetate.Morphology and Polymorph evolution of vanillin were discussed in terms of solvent,supersaturation ratio and silica template.PXRD,DSC,FTIR and microscope were used to identify Polymorphs of vanillin.Results showed that the nucleated Polymorphs of vanillin depended largely on the solvent,supersaturation ratio and silica template.Low supersaturation ratios favor the nucleation of stable form I in water,and high supersaturation ratio exceeds 7 generating 100%metastable form II.However,if the supersaturation ratio is too high(S>8),liquid-liquid phase separation will occur,and no crystals could be obtained.In other solvents such as ethanol,isopropanol and ethyl acetate,only form I was obtained.However,it should be noted that the morphology of form I prepared in ethanol,isopropanol and ethyl acetate is distinct from that obtained in water,the former is flake-like and the latter is rod-like.The nucleation of vanillin from different solution was also studied with the presence of SiO_(2),SiO_(2)-NH_(2)and SiO_(2)−COOH templates,which did not change the nucleated Polymorph of vanillin,but changed the nucleation and growth rate of stable form I.

关键词： Vanillin Supersaturation ratio Nucleation Polymorph Template

Micro-seeding and soft template effects on the control of Polymorph and morphology of HMX micro particles in solvent-antisolvent process

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Defence Technology（防务技术） 2017年第6期13卷 392-396页

作者： Sajjad Damiri Shahriar Namvar Hadi Panahi Department of Applied Chemistry Maleke-ashtar University of TechnologyShahin-shahrEsfahanIran

A seeding strategy was developed in the preparation of cyclotetramethylenetetranitramine(HMX)explosive micro-particles by solvent-antisolvent method, to control their Polymorphs from dangerous gamma(y) type to the desired and standard beta(β) form with the size distribution of <10.0 μm, by using a low concentration of β-HMX fine particles as micro-seed in the antisolvent medium. All products were characterized by X-ray diffraction(XRD), scanning electron microscopy(SEM), and dynamic light scattering particle size analyzer. In the next step, the effective factors on the sizes and morphologies of micro-particles in the presence and absence of two soft templates of poly(ethylene glycol)-400(PEG-400) polymer and coconut fatty acid diethanolamide(lauramide) surfactant were investigated. The results of experiments showed that using of water-soluble PEG-400 in the low antisolvent temperatures leads to the production of very spherical particles. Also non-ionic surfactant of lauramide, direct the crystal growth to needle-like structures. The advantages of this method are its capability for the simple production of β-HMX micro-particles in the large scale production process, with the various crystal structures and particles size distributions.

关键词： Micro seeding Polymorph HMX Explosive Micro-particle Solvent-antisolvent process

Synthesis, Characterization and Control of Proportion of Polymorph C in ITQ-16 and ITQ-17 Films

在线全文

学校读者我要写书评

暂无评论

Chemical Research in Chinese Universities 2016年第6期32卷 895-901页

作者： CHEN Yanli FENG Lai College of Physics Optoelectronics and Enevgy Soochow University Suzhou 215006 P. R. China School of Materials Science and Engineering Tianjin University of Technology Tianjin 300384 P. R. China

Continuous ITQ-16 and ITQ-17 films on silicon wafer were prepared in fluoride media using TEAOH asorganic structure-directing agent. The proportion ofPolymorph C in the as-synthesized ITQ-16 and ITQ-17 films wasdetermined via X-ray diffraction characterization. The proportion of Polymorph C in the ITQ-16 and 1TQ-17 filmswas controlled via optimizing the compositions of the reaction mixtures and reaction conditions, such as varyingthe Si/Ge molar ratio and adding n-propyl alcohol as a solvent in the reaction mixture, The Ge atoms in the reactionmedia strongly increased the crystallization of Polymorph C in ITQ-16 and ITQ-17 films. Moreover, the stabilizingand buffering effect of n-propyl alcohol on crystal growth further enhanced the proportion of Polymorph C in theITQ-16 and ITQ-17 films. For potential catalytic applications, A1 was incorporated into the framework ofPolymorphC, and a pure phase of Polymorph C in Al-ITQ-17 film was achieved from the synthesis gel in the n-propyl alcohol phase.

关键词： Zeolite beta ITQ-16 ITQ-17 Polymorph C

Morphology and Polymorph Control of Calcium Carbonate via a Facile Additive-Free Route

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Wuhan University Journal of Natural Sciences 2020年第5期25卷 423-427页

作者： ZHAO Dazhou School of Chemistry&Chemical Engineering Shaanxi Xueqian Normal UniversityXi'an 710100ShaanxiChina

In this paper,we reported a facile additive-free route for synthesizing calcium carbonate(CaCO3)with different morphologies and Polymorphs by a precipitation reaction method between Ca(CH3COO)2 and NaHCO3 in water and ethylene glycol(H2O/EG)mixed solvent.It has been found that the concentration of Ca^2+ and HCO3^-,the volume ratio of H2O/EG and the reaction temperature are turned out to be important parameters for the morphology and Polymorph of CaCO3.Various interesting morphologies,such as the spherical,elliptoid,spindle-like,petal-like,cricoid,cubic,plate-like and rod-like can be easily obtained.Pure Polymorphs of vaterite,calcite and aragonite can also be tuned by adjusting experimental conditions.The studies might be helpful to provide new insights into the morphosynthesis and crystalline phase control of other inorganic materials.O 611.4;O 643.1.

关键词： calcium carbonate precipitation reaction water and ethylene glycol(H2O/EG) morphology Polymorph

Multi-interface collaboration of graphene cross-linked NiS-NiS_(2)-Ni_(3)S_(4) Polymorph foam towards robust hydrogen evolution in alkaline electrolyte

在线全文

学校读者我要写书评

暂无评论

Nano Research 2021年第12期14卷 4857-4864页

作者： Haiqing Wang Wenjing Zhang Xiaowei Zhang Shuxian Hu Zhicheng Zhang Weijia Zhou Hong Liu Collaborative Innovation Center of Technology and Equipment for Biological Diagnosis and Therapy in Universities of Shandong Institute for Advanced Interdisciplinary Research(iAIR)University of JinanJinan250022China Beijing Computational Science Research Center Beijing100193China Tianjin Key Laboratory of Molecular Optoelectronic Sciences Department of ChemistrySchool of ScienceTianjin UniversityTianjin300072China State Key Laboratory of Crystal Materials Shandong UniversityJinan250100China

Electrocatalytic hydrogen production in alkaline media is extensively adopted in industry. Unfortunately, further performance improvement is severely impeded by the retarded kinetics, which requires the fine regulation of water dissociation, hydrogen recombination, and hydroxyl desorption. Herein, we develop a multi-interface engineering strategy to make an elaborate balance for the alkaline hydrogen evolution reaction (HER) kinetics. The graphene cross-linked three-phase nickel sulfide (NiS-NiS_(2)-Ni_(3)S_(4)) Polymorph foam (G-NNNF) was constructed through hydrothermal sulfidation of graphene wrapped nickel foam as a three-dimensional (3D) scaffold template. The G-NNNF exhibits superior catalytic activity toward HER in alkaline electrolyte, which only requires an overpotential of 68 mV to drive 10 mA·cm^(−2) and is better than most of the recently reported metal sulfides catalysts. Density functional theory (DFT) calculations verify the interfaces between nickel sulfides (NiS/NiS_(2)-Ni_(3)S_(4)) and cross-linked graphene can endow the electrocatalyst with preferable hydrogen adsorption as well as metallic nature. In addition, the electron transfer from Ni_(3)S_(4)/NiS_(2) to NiS results in the electron accumulation on NiS and the hole accumulation on Ni_(3)S_(4)/NiS_(2), respectively. The electron accumulation on NiS favors the optimization of the H* adsorption, whereas the hole accumulation on Ni_(3)S_(4) is beneficial for the adsorption of H_(2)O. The work about multi-interface collaboration pushes forward the frontier of excellent Polymorph catalysts design.

关键词： hydrogen evolution reaction nickel sulfide interface engineering Polymorph heterointerface

The crystal structure of mimetite-2M,a new Polymorph of mimetite from Xianghualing tin-polymetallic orefield,Hunan Province,P.R.China

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

The crystal structure of mimetite-2M,a new polymorph of mime...

Polymorph CONTROL OF ANTIMONY WHITE(Sb_2O_3)PREPARED BY HYDROMETALLURGY METHOD

中国科学院地质与地球物理研究所2013年度（第13届）...

作者： Zhuming Yang Kuishou Ding Jeffrey de Fourestier He Li Institute of Geology and Geophysics Chinese Academy of Sciences

Mimetite-2M,ideally Pb(AsO)Cl,is a new Polymorph of mimetite in the apatite group occurring as a skarn mineral in the Xianghualing Sn-polymetallic ore field,Linwu County,Hunan Province,P.R.China.The associated minerals include fluorite, calcite,cassiterite,pyrite,sphalerite,pyrrhotite,galena,spinel,zinnwaldite and phlogopite.Mimetite-2M is pale yellow and forms pseudo-hexagonal columnar crystals of about 1 mm to 5 mm in size.The empirical formula is PbAsOCl. The super-structure reflections of mimetite were observed and require doubling of the a-axes of mimetite-H.The crystal structure was refined in space group P2;with a = 20.422(4),b= 7.4379(15),c= 20.435(4) A.,β= 119.95(3)°,V = 2689.5(9) A,Z = 8, R1 = 0.067,wR2 = 0.180. The largest differences in positions of analogous atoms between the hexagonal phase mimetite-H and monoclinic mimetite-2M occur in the positions relative to the O(3) and Cl atoms in the hexagonal phase.The actual positions of the atoms O(3) to O(3) and Cl in mimetite-2M results in the reduction of symmetry to monoclinic with both doubled a-axes of the hexagonal phase.

关键词： mimetite mimetite-2M Polymorph apatite group chemical composition crystal structure

来源： cnki会议评论

在线全文

cnki会议

学校读者我要写书评

暂无评论

中国有色金属学会会刊:英文版 1997年第4期7卷 119-123页

作者： Zhang Duomo Xiao Songwen Cho Tongrae Liu Zhihong Ge Rongde Chen Huiguang Guo Xueyi Department of Nonferrous Metallurgy Central South University of TechnologyChangsha 410083 College of Engineering Chung Nam National UniversitySouth Korea

The effects of reaction solvent, the properties of Sb 4O 5Cl 2 material and the ligand additives on the reaction rate and Polymorph of antimony white(Sb 2O 3) in the reaction of Sb 4O 5Cl 2 transforming into Sb 2O 3 have been investigated by XRD and IR method. It is revealed that the reaction solvent and the properties of Sb 4O 5Cl 2 are the key factors affecting the reaction rate. The Polymorph of antimony trioxides is determined by the reaction mechanism, i.e. the coordination state of the antimony activated complex. Adding a little ligand such as EDTA is the most economical and effective method of synthesizing cubic antimony white(Sb 2O 3)in hydrometallurgical transformation process.

关键词： antimony white Polymorph antimony activated complex structure selecting catalyst

Application of functionalized magnetic silica nanoparticles for selective induction of three coumarin metastable Polymorphs

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Chemical Engineering 2022年第10期50卷 155-167页

作者： Yiqing Chen Xin Huang Suping Ding Yaoguang Feng Na Wang Hongxun Hao National Engineering Research Center of Industrial Crystallization Technology School of Chemical Engineering and TechnologyTianjin UniversityTianjin 300072China Collaborative Innovation Center of Chemical Science and Engineering(Tianjin) Tianjin 300072China School of Chemical Engineering and Technology Hainan UniversityHaikou 570228China

The precise control of active pharmaceutical ingredient(API)crystal nucleation and Polymorphism is a key consideration in pharmaceutical manufacturing.In this study,tunable nanoparticles were developed to regulate the nucleation process of coumarin.Magnetic silica nanoparticles with four different functional groups(-NH_(2),-COOH,-SH,-NCO)were prepared and coated on the substrate for inducing the crystallization of coumarin.Confined melt crystallization and microspacing sublimation crystallization methods were used to investigate the regulation mechanism.The results indicated that three metastable forms of coumarin can be obtained as pure components based on the combined influence of crystallization methods and functionalized nanoparticles.FormⅡcould be selectively obtained by microspacing sublimation crystallization on Fe_(3)O_(4)@SiO_(2)-SH substrates,and FormⅣcould be obtained by confined melt crystallization on Fe_(3)O_(4)@SiO_(2)-NCO substrates.FormⅢcould be obtained by further heating FormⅣcrystals to 52℃on Fe_(3)O_(4)@SiO_(2)-NCO substrates.Moreover,the polarized light microscopy results also indicated that the introduction of nanoparticles could also increase the stability of the metastable crystalline forms of coumarin.Finally,the diffusion and surface dynamics during nanoparticle induced crystallization were comparatively investigated and the corresponding Polymorphic selectivity mechanism was proposed.

关键词： Polymorph Functional nanoparticles Surface interactions Heterogeneous nucleation

Structural landscape investigations on bendable plastic crystals of isonicotinamide Polymorphs

在线全文

学校读者我要写书评

暂无评论

Chinese Chemical Letters 2022年第8期33卷 4069-4073页

作者： Jianting Li Jiaquan Li Hongji Liu Li Zhang Yang Lu Zhengzheng Zhou NMPA Key Laboratory for Safety Evaluation of Cosmetics Guangdong Provincial Key Laboratory of Tropical Disease ResearchDepartment of Hygiene Inspection&Quarantine ScienceSchool of Public HealthSouthern Medical UniversityGuangzhou 510515China Beijing City Key Laboratory of Polymorphic Drugs Institute of Materia MedicaChinese Academy of Medical Sciences and Peking Union Medical CollegeBeijing 100050China

Three Polymorphs(forms I,II and V)of isonicotinamide(INA)were mechanically flexible and exhibited one-dimensional(1 D)plasticity.Anisotropic intermolecular interactions contribute to the plasticity of single crystals:weak dispersive interactions between slip planes such as 1 D columns in forms I and II or 2 D layers in form V were stabilized by strong hydrogen bonds,allowing the layer or column's surface to glide smoothly without hindrance.The disparity of intermolecular interactions on plastic properties of INA Polymorphic crystals was confirmed by energy framework analysis,nanoindentation tests and micro-Raman spectroscopy.The crystal which exhibits plastic property provides a promising application in pharmaceuticals and material sciences.

关键词： Isonicotinamide Polymorph Plasticity Slip plane Bending crystal

Synthesis and structure of Au_(19)Ag_4(S-Adm)_(15) nanocluster:Polymorphs and optical properties

在线全文

学校读者我要写书评

暂无评论

Chinese Chemical Letters 2021年第1期32卷 565-568页

作者： Xuemei Fu Xinzhang Lin Xiuqing Ren Hengjiang Cong Chao Liu Jiahui Huang Gold Catalysis Research Center State Key Laboratory of CatalysisDalian Institute of Chemical PhysicsChinese Academy of SciencesDalian 116023China University of Chinese Academy of Sciences Beijing 100049China College of Chemistry and Molecular Sciences Engineering Research Center of Organosilicon Compounds&MaterialsMinistry of EducationWuhan UniversityWuhan 430072China

Polymorphism is a common phenomenon in nature.Here,we report one-pot wet chemical method to synthesize two Polymorphs of Au_(19)Ag_(4)(S-Adm)_(15) nanocluster protected by 1-adamantanethiol(HSAdm),which adopt P-1 and P2_(1)/c space group respectively.The crystal structures of two Polymorphs were determined by X-ray crystallography.Compared to the previously reported Au_(19)Ag_(4)(S-Adm)_(15)nanocluster adopting P2_(1)/n space group,Polymorphs of Au_(19)Ag_(4)(S-Adm)_(15) with P-1 and P2_(1)/c space group show the different optical properties.Moreove r,Au_(19)Ag_(4)(S-Adm)_(15) with P-1 space group exhibits good thermal stability.Meanwhile,we investigated the effect of solvent and molar ratio of metal precursors on the Polymorphs.This work provides an insight to Polymorphs of metal nanoclusters.

关键词： Au_(19)Ag_4(S-Adm)_(15) Alloy nanocluster Polymorph Fluorescence Thermal stability