Synthesis Of Inorganic Materials Research Articles

Effect of ethanol on the aggregation properties of cetyltrimethylammonium bromide surfactant

Surfactant aggregation properties in aqueous and mixed organic/aqueous solutions have attracted considerable interests especially for the applications to the template synthesis of nanoporous inorganic materials. In this work, we study the aggregation behavior of cetyl trimethylammonium bromide surfactant in both aqueous and mixed water/ethanol solutions by the steady-state fluorescence probe technique. The critical micelle concentration (CMC) and the micelle aggregation number were determined in solutions with different ethanol contents. The CMC increases and the aggregation number decreases with increasing ethanol content in solutions. The effect of ethanol on the micelle formation can be treated as a structure breaking process. The density functional theory was used to calculate the charge density distribution over the surfactant molecules in different solvents. The results obtained reveal that the micelle size distribution in solutions can be adjusted by varying the content of ethanol in solvents.

Selective Synthesis of Monazite- and Zircon-type LaVO4 Nanocrystals

Pure monoclinic (m-) and tetragonal phased (t-) LaVO(4) nanocrystals could be obtained by a hydrothermal method in a controllable way with additives. It is found that chelating ligands, such as ethylenediaminetetraacetic acid [EDTA or H(4)L, where L(4-) = (CH(2)COO)(2)N(CH(2))(2)N(CH(2)COO)(2)(4-)], favor the formation of t-LaVO(4) and can induce the polymorph transformation from stable m-LaVO(4) to metastable t-LaVO(4). Further studies demonstrated the important roles of chelating ligands in this transformation process. Careful investigation over the phase transition from t- to m-LaVO(4) was also conducted with high-temperature X-ray diffraction (HTXRD) studies. The phase transition occurred at 850 degrees C, which is about 250 degrees C higher than for the bulk. The enhanced thermal stability of the nanosized metastable t-LaVO(4) may come from the small size effect. Our capability of obtaining and stabilizing t-LaVO(4) not only benefits the wider applications based on LaVO(4) due to the improved luminescent and catalytic performance but also provides a new idea in the studies of polymorph control and selective synthesis of inorganic materials.

Synthesis and Electrochemical Properties of Nonstoichiometric Spinel Phase (Li<sub>1.02</sub>Mn<sub>1.90</sub>Y<sub>0.02</sub>O<sub>4-y</sub>F<sub>0.08</sub>) for Lithium Ion Battery

A nonstoichiometric spinel phase (Li1.02Mn1.90Y0.02O4-yF0.08) was synthesized using natural polymer net method. It was characterized by XRD and XPS. The particle size and shape of the expected compounds were observed by Transmission Electron Microscopy technique. The composition of new spinel phase was checked by ICP. The electrochemical properties of the new spinel phase (Li1.02Mn1.90Y0.02O4-yF0.08) were also investigated. The results showed that the Li1.02Mn1.90Y0.02O4-yF0.08 behaved excellent recharge ability to compare with stoichiometric LiMn2O4. The initial discharge capacity of the battery was 128.5 mAh/g when current density was 1 mA·cm-2 over voltage range of 4.4 to 3.0V. The discharge capacity could retain about 96% after 100 cycles when metallic lithium was anode. The outstanding electrochemical properties of Li1.02Mn1.90Y0.02O4-yF0.08 make it possible as a promising cathode material. The novel synthesis method provides a simple and effective route for inorganic material synthesis.

Nanoparticle Ring Structures based on Protein Assemblies

AbstractThe bottom-up wet-chemical synthesis of inorganic materials provides tools for generating nanostructures from particles to one-dimensional structures, but these conventional chemical techniques usually offer little control over the deposition of metals or metal particles into nanosized ring structures although interesting properties and applications, e.g., Aharonov-Bohm rings are expected. Our results provide a straightforward and rapid wet-chemical synthesis to ring-like metal particle arrays. Applying appropriate conditions, tubulin dimers, proteins of 4-5 nm diameter and a length of 8 nm, self-assemble by specific recognitions capabilities into defined superstructures. Ca2+ ions, e.g., direct the assembly of tubulin into 50 nm sized, ring-like structures. In our approach, these ring-like protein assemblies serve as a functionalized scaffold where the metal particles are generated in situ and deposited into spiral-shaped particle arrays, reflecting the arrangement of the protein subunits within the assembly. The resulting size and crystalline structure of the materials were examined using transmission electron microscopy and scanning force microscopy.

Tectonic arrangement of BaCO3 nanocrystals into helices induced by a racemic block copolymer

Morphosynthesis strategies inspired by biomineralization processes gives access to a wide range of fascinating and useful crystalline mesostructures. Biomimetic synthesis of inorganic materials with complex shapes can now be used to control the nucleation, tensorial growth, and alignment of inorganic crystals in a way previously not practicable. Double hydrophilic block copolymers (DHBCs) consisting of a hydrophilic block strongly interacting with inorganic minerals, and a non-interacting hydrophilic block, were recently introduced for the control of mineralization reactions. DHBCs are 'improved versions' of the previously used polyelectrolytes or amphiphiles and are extraordinarily effective in crystallization control. Here, we report on the formation of helices of achiral BaCO(3) nanocrystals in the presence of a racemic DHBC suggesting that a helical alignment can be induced by racemic polymers through selective adsorption on the (110) face of nanocrystals. This mechanism is the key for a better understanding of the self-assembly of chiral organic-inorganic superstructures that don't follow a direct template route.

Morphological control of strontium oxalate particles by PSMA-mediated precipitation reaction

In this paper, strontium oxalate particles with different morphologies could be easily obtained by a precipitation reaction of sodium oxalate with strontium chloride in the absence and presence of poly-(styrene-alt-maleic acid) (PSMA). The as-prepared products were characterized with scanning electron microscopy and X-ray diffraction. The effects of pH, aging time and concentration of PSMA on the phase structures and morphologies of the as-prepared strontium oxalate particles were investigated and discussed. The results showed that strontium oxalate particles with various morphologies, such as, bi-pyramids, rods, peanuts, and spherical particles, etc., could be obtained by varying the experimental conditions. PSMA promoted the formation of strontium oxalate dihydrate (SOD) phase. Suitable pH values (pH 7 and 8) favor the formation of the peanut-shaped SrC 2O 4 particles. This research may provide new insight into the control of morphologies and phase structures of strontium oxalate particles and the biomimetic synthesis of novel inorganic materials.

Direct imaging and mesoscale modelling of phase transitions in a nanostructured fluid

The kinetics of phase transitions is essential for understanding pattern formation in structured fluids. These fluids play a key role in the morphogenesis of biological cells, and they are very common in pharmaceutical products and plastic materials. Until now, it has not been possible to follow phase transitions in structured fluids experimentally in real time and with high spatial resolution. Previous work has relied on static images and indirect experimental evidence from spatially averaging scattering experiments. Simulating the processes with computer models is a further challenge because of the multiple time and length scales involved. Our movies based on in situ scanning force microscopy show the time sequence of the elementary steps of a phase transition in a fluid film of block copolymer from the cylinder to the perforated lamella phase. The movies validate a versatile simulation model that gives physical insight into the nature of the process. Our approach provides a means of improving the study and understanding of pattern formation processes in nanostructured fluids. We expect a significant impact on nanotechnology where block copolymers serve as self-organized templates for the synthesis of inorganic nanostructured materials.

Role of templating agents on the growth morphology of AIPO4

Large numbers of techniques are known to yield advanced materials, particularly ceramics, and currently the templating techniques, where the templating agents are used to control the nucleation of inorganic clusters from the aqueous or nonaqueous solution are gaining importance [1, 2]. Preorganized architectures consisting of functionalized surfaces act as templates for the nucleation and growth of inorganic materials [3]. The templates are frequently used to promote the formation of the desired structure during synthesis of inorganic materials and it is understood that the templating agents, normally organic nitrogen-containing bases, may serve as structure directing agents, as buffers or as void fillers [4]. The templating is a well-known step for the nucleation and growth of inorganic compounds in the biomineralization process, where the inorganic– organic interaction leads to preorganization, nucleation, and growth of biomaterials [5]. Several groups have investigated the preparation of aluminum phosphate using a templating agent in a nonaqueous medium [6–8]. In the last few years, the research on the molecular sieves particularly, Al-phosphate, has increased due to its importance as catalyst carrier for the oxidation of linear alkanes using molecular oxygen [9] and its possible use in nano-laser tubes [10]. In this letter, the effect of templating agents on the synthesis of microporous AlPO4 is discussed. We used aluminum-isopropoxide to prepare boehmite sol, which was reacted with orthophosphoric acid to yield AlPO4 in ethylene glycol medium. Al-isopropoxide with purity >99.96% was prepared by reacting aluminum metal with isopropyl alcohol followed by vacuum distillation. In the present investigation, 100 g of Al-isopropoxide were hydrolyzed in 1000 cm3 distilled water. Subsequently, 50 cm3 of the Al-sol was dissolved in 100 cm3 ethylene glycol and reacted with H3PO4 acid at 373 K for 3 h to yield AlPO4 by the following reaction.

Surfactant-templated nanomaterials synthesis

The ability of amphiphilic compounds to self-assemble into well-defined structures can be taken advantage of for synthesis of inorganic materials with nanometer dimensions. The principle, which is biomimetic in character, is discussed with special attention put on three areas: microemulsion-based synthesis of nanoparticles, preparation of mesoporous materials from surfactant templates, and surfactant-mediated crystallization.

Glycothermal synthesis of metal oxides

The author has been exploring the synthesis of inorganic materials in organic solvents at temperatures(200–300 °C) higher than their boiling points (solvothermal reaction), and has developedvarious reaction methods for the synthesis of ultrafine particles of metal oxides. Inthis paper, the reactions of aluminium compounds (aluminium hydroxide(Al(OH)3; gibbsite), aluminium alkoxides, and aluminium salts) in various organic solvents (alcohols,glycols, aminoalcohols, and inert organic solvents) are first reviewed, and reactionmechanisms and effects of the starting materials and solvents on the products arediscussed. Then, the specificity of the use of glycols, especially 1,4-butanediol (glycothermalreaction), is clarified, and glycothermal synthesis of crystalline mixed oxides such asyttrium aluminium garnet is described. Finally, the use of the solvothermally preparedproducts as the catalyst materials is described.

A new route for organic–inorganic hybrid material synthesis through reactive processing without solvent

A new route to elaborate organic–inorganic hybrid materials is presented. It is based upon two successive steps, the former is the crosslinking of polymer which contains pendant ester groups such as poly(ethylene–co-vinyl acetate) (EVA) through ester–alkoxysilane interchange reaction in molten state in the presence of dibutyltin oxide as catalyst. The latter is the hydrolysis–condensation reactions of available alkoxysilane groups in the polymer network leading to the silica network co-grafted onto the organic network. More particularly the hydrolysis–condensation reactions in solid state leading to the silica network grafted and confined in the organic network are addressed in the present work. The progress of the hydrolysis–condensation reactions was investigated by gas chromatography, FT-IR spectroscopy, 29Si solid NMR, volume swelling degree at equilibrium and dynamic mechanical analysis. Two side reactions have been evidenced leading to alcohol groups grafted onto EVA. The silanols and these alcohol groups can participate to hydrogen bonds between ester and silica domains. The organic–inorganic hybrids elaborated according to this new chemical route exhibit improved mechanical and thermomechanical properties with respect to the EVA while having an elastomeric behavior with respect to the nanocomposite synthesized by in situ polymerization of tetraethoxysilane.

Synthesis and Ab Initio Structure Determination from Powder Diffraction Data of K<sub>4</sub>Sn<sub>2</sub>Si<sub>6</sub>O<sub>18</sub>

Abstract. The crystal structure of a new potassium stannosilicateK 4 Sn 2 Si 6 O 18 (AV -11) has been determined ab initio from powder -Xray diffraction data. The unit cell is trigonal, space group R 3 (no. 146), Z=3 with cell dimensions a = 10.1587, c = 14.8039 A, γ= 120o, V = 1323 3A . The structure is made up of SnO 6 octahedra and SiO 4 tetrahedra by sharing corners. The SiO 4 tetrahedra form a helix chain, periodically repeating every six tetrahedra. These chains extend along the [001] direction and are linked by isolated Sn-O octahedron giving a mixed framework. Introduction The synthesis of inorganic microporous materials with mixed framework of interconnected octahedral- and tetrahedral-oxide is presently raising considerable interest [1]. Among these mixed framework materials, more than twenty stannosilicates are known and a few tannosilicate phasess have been crystallised from hydrothermal conditions ([2] and ref. therein). In the course of our work on the synthesis of stannosilicates, we found a patent by the Exxon Research and Engineering Company, 1992 [3] where the synthesis of six stannosilicates are reported, but with no structural information given. One of these materials, phase X, presents a -ray pattern similar to the material Xreported here. Thus, we wish to report the synthesis and the structural determination by powder XRD data of a new potassium stannosilicate, named AV-11 (Aveiro microporous solid no.11).

Synthesis of Inorganic Materials by 28 GHz microwave irradiation

Synthesis of Inorganic Materials by 28 GHz microwave irradiation

Effects of PAA additive and temperature on morphology of calcium carbonate particles

Calcium carbonate particles with various shapes were prepared by the reaction of sodium carbonate with calcium chloride in the absence and presence of a polyacrylic acid (PAA) at 25°C and 80°C, respectively. The as-prepared products were characterized with scanning electron microscopy and X-ray diffraction. The effects of pH, temperatures, aging time and concentration of PAA and CaCO 3 on the crystal form and morphologies of the as-prepared CaCO 3 were investigated. The results show that pH, temperatures, concentration of PAA and CaCO 3 are important parameters for the control of morphologies of CaCO 3. Various crystal morphologies of calcite, such as, plates, rhombohedras, rectangles, ellipsoids, cubes, etc. can be obtained depending on the experimental conditions. Especially, the monodispersed cubic calcite particles can be produced by PAA addition at 80°C. Moreover, higher temperature is beneficial to the formation of monodispersed cubic or rectangular calcite particles. This research may provide new insight into the control of morphologies of calcium carbonate and the biomimetic synthesis of novel inorganic materials.

Mesoporous carbon nanotubes for use as support in catalysis and as nanosized reactors for one-dimensional inorganic material synthesis

Mesoporous multi-walled carbon nanotubes (MWNTs) with an average inner diameter of about 50 nm were successfully used as a one-dimensional catalyst support either in gas-phase, i.e. selective oxidation of H 2S into elemental sulfur in a thrickle-bed configuration, or in liquid-phase reactions, i.e. selective hydrogenation of nitrobenzene into aniline or Friedel-Crafts benzoylation reactions. On one hand, the combination of the small size, i.e. high external surface area, and of the tube structure, i.e. confinement effect, allowed a significant improvement of the catalytic performance when compared to that obtained on traditional grain shaped catalysts as observed in the selective oxidation of H 2S and the selective hydrogenation of nitrobenzene reactions. On the other hand, the confinement effect induced by the high aspect ratio of the tubes could, in addition, be effectively used for the synthesis of one-dimensional nanowire zeolitic materials under non-hydrothermal macroscopic conditions. Carbon nanotubes template were removed by combustion leaving behind zeolite nanowires which were made up of zeolite particles of about 10–20 nm. The zeolitic catalysts exhibit a high benzoylation activity compared to that of the commercial one due to its high external surface area.

Application of a novel Split&Pool-principle for the fully combinatorial synthesis of functional inorganic materials

In the field of high throughput experimentation (HTE) related to materials sciences and catalysis a large number of test methods and analytical tools have been developed in the last years. As a consequence of the increasing parallelization and integration of the reactor and analysis systems, the requirements for the synthesis methodologies are rising extremely: smallest amounts of material samples of, i.e. different multi component mixed oxides in the μg- or gram-range have to be synthesized reproducibly and fully automated. In order to meet these challenges, the combination of different expert skills in the fields of inorganic synthesis, robotics, automation and related fields are of major importance. Real combinatorial chemistry, meaning the combinatorial permutation of element combinations or synthesis parameters involving statistical synthetic approaches leading to true combinatorial libraries of new functional materials supported by computer aided designs, was not presented yet in scientific community of inorganic solid state chemistry. We present here for the first time a tool for synthetic chemistry, originally developed with the application focus on molecular libraries, to produce inorganic solid state materials. With the so-called Split&Pool (S&P)-principle, it is possible to produce highly diverse materials libraries in the range of 10 3–10 8 samples with a very simple workflow. Characterization with μ-XRF, optical microscopy and other analysis tools prove the potential of the presented synthesis technique. A powerful enhancement of this synthesis tool is our recently presented “single bead reactor” (SBR), allowing efficient testing of the libraries created by the Split&Pool methodology.

Synthesis and electrochemical characterization of nonstoichiometry spinel phase (Li xMn 1.93Y 0.02O 4) for lithium ion battery applications

A nonstoichiometric spinel phase (Li x Mn 1.93Y 0.02O 4) was synthesized using reheological phase reaction method. It was characterized by XRD and XPS techniques. Both particle size and shape of the spinel phase were observed by the method of transmission electron microscopy. The chemical composition of new spinel was determined by ICP analysis. The electrochemical properties of new spinel phase (Li x Mn 1.93Y 0.02O 4) were also investigated. The result showed that the Li x Mn 1.93Y 0.02O 4 behaved excellent recharge ability to compare with stoichiometric LiMn 2O 4. The initial discharge capacity reached 126 mA h g −1 and retained by 95.2% after 50 cycles. The outstanding electrochemical properties of Li x Mn 1.93Y 0.02O 4 make it passable as a promising cathode material. The novel method provides a simple, practicable and effective route for inorganic material synthesis.

Silica Glass from Aerosil by Sol-Gel Process: Densification and Textural Properties

Sol-gel processes allow the synthesis of inorganic materials from solutions of molecular precursors. These precursors can be either organic, inorganic, or a mixture of the two. The aim of this work is the preparation of aqueous solutions consisting of Aerosil OX 50 (fumed silica) using small amount of additives like ammonium fluoride NH4F (less than 2%), which are dried at room temperature in order to obtain monolithic gels. These are then densified at temperatures below 1200°C and sintered at 1300°C in order to obtain pure silica glass. The textural properties evolution of these gels is investigated as a function of temperature by thermal analysis (mass loss, shrinkage, and density) and scanning electron microscopy.

The MrgA Multimeric Complex: a self-assembled nanostructure for inorganic synthesis

AbstractUtilization of protein cages in biomimetic chemistry allows for the deposition of inorganic materials within an organic construct, controlling the size and amount of material deposited within a constrained reaction environment. Previously, protein cages such as viral capsids and ferritins have been used in the constrained synthesis of inorganic materials. The MrgA protein displays a high sequence homology to both bacterial DNA-protecting proteins (Dps) found in many bacterial genera and Ferritin-like proteins (Flp), which have been shown to functionally sequester and store iron in a biologically available form. Here we demonstrate recombinant production, purification and characterization of the MrgA protein and provide evidence that this protein self-assembles to form a multimeric complex. This complex demonstrates characteristics similar to that of ferritin-like proteins such as resistance to iron toxicity, iron incorporation, and resistance to thermal and chemical denaturation. The ability to deposit iron within the putative internal cavity of this protein cage will allow the MrgA complex to be utilized as a spatially constrained reaction vessel for nanomaterial synthesis of other inorganic materials. From a materials science perspective, it will be interesting to see if these organic/inorganic hybrid materials can be harnessed for catalysis, nanomagnetics, and other applications.

ソフト化学的手法による機能性無機材料の合成と制御

ソフト化学的手法による機能性無機材料の合成と制御