Pursuing the Crystallization of Mono- and Polymetallic Nanosized Crystalline Inorganic Compounds by Low-Temperature Wet-Chemistry and Colloidal Routes (original) (raw)
Nanoporous Solids: How Do They Form? An In Situ Approach
Chemistry of Materials, 2014
Understanding the crystallization mechanisms of nanoporous solids remains one of the most challenging issues in materials science. This Short Review focuses on the use of in situ nuclear magnetic resonance (NMR) spectroscopy under hydrothermal conditions to investigate the structure, dynamics, and stability/reactivity of the soluble species present in the synthesis medium during the crystallization. We describe how the formal SBU (secondary building units) concept for solid construction can experimentally be investigated, checked, and validated on some representative purely inorganic porous phosphates as well as hybrid metal organic framework (MOF) materials. We also discuss the specific role of reactive species identified in solution to lead to intermediate or more elaborate structures such as the PNBU (prenucleation building units) or the MBU (neutral molecular building units), respectively. In certain cases, the proposed models could not to be generalized depending on the reaction conditions, the chemistry of the metallic cation, and the stability/solubility of the target phase. We also point out that experimental and theoretical approaches for identification and enumeration of existing and new SBU are essential for the discovery and/or structure determination of new materials.
Room temperature synthesis of crystalline metal oxides
Journal of materials Science, 1997
Crystalline titanium dioxide powders have been synthesized as either rutile or anatase from aqueous solutions at low temperatures (T≤ 100C) and atmospheric pressure. First, a sol is prepared by the hydrolysis of a titanium alkoxide in an acidic solution. The ...
Comptes Rendus Chimie, 2010
The aim of this paper is to show that a very simple but well controlled chemistry in an aqueous medium allows one to efficiently control the main characteristics of oxide nanoparticles. Examples concerning titania, alumina, iron and manganese oxides are discussed to illustrate various effects on the control of size, shape and structure of nanoparticles. Some examples of functionalization of these particles are also illustrated. Experimental data, procedures and detailed references can be found in the cited literature. To cite this article: J.-P. Jolivet et al., C. R. Chimie 13 (2010). # 2009 Académie des sciences. Published by Elsevier Masson SAS. All rights reserved.
Journal of Colloid and Interface Science, 2011
A new solid state organometallic route to embedded nanoparticle-containing inorganic materials is shown, through pyrolysis of metal-containing derivatives of cyclotriphosphazenes. Pyrolysis in air and at 800°C of new molecular precursors gives individual single-crystal nanoparticles of SiP 2 O 7 , TiO 2 , P 4 O 7, WP 2 O 7 and SiO 2 , depending on the precursor used. High resolution transmission electron microscopy investigations reveal, in most cases, perfect single crystals of metal oxides and the first nanostructures of negative thermal expansion metal phosphates with diameters in the range 2-6 nm for all products. While all nanoparticles are new by this method, WP 2 O 7 and SiP 2 O 7 nanoparticles are reported for the first time. In situ recrystallization formation of nanocrystals of SiP 2 O 7 was also observed due to electron beam induced reactions during measurements of the nanoparticulate pyrolytic products SiO 2 and P 4 O 7 . The possible mechanism for the formation of the nanoparticles at much lower temperatures than their bulk counterparts in both cases is discussed. Degrees of stabilization from the formation of P 4 O 7 affects the nanocrystalline products: nanoparticles are observed for WP 2 O 7 , with coalescing crystallization occurring for the amorphous host in which SiP 2 O 7 crystals form as a solid within a solid. The approach allows the simple formation of multimetallic, monometallic, metal-oxide and metal phosphate nanocrystals embedded in an amorphous dielectric. The method and can be extended to nearly any metal capable of successful coordination as an organometallic to allow embedded nanoparticle layers and features to be deposited or written on surfaces for application as high mobility pyrophosphate lithium-ion cathode materials, catalysis and nanocrystal embedded dielectric layers.
Ion irradiation effects in nonmetals: formation of nanocrystals and novel microstructures
Materials Research Innovations, 2000
Ion implantation is a versatile and powerful technique for producing nanocrystal precipitates embedded in the near-surface region of materials. Radiation effects that occur during the implantation process can lead to complex microstructures and particle size distributions, and in the present work, we focus on the application of these effects to produce novel microstructural properties for insulating or semiconducting nanocrystals formed in optical host materials. Nanocrystal precipitates can be produced in two ways: by irradiation of pure (i.e., non-implanted) crystalline or amorphous materials, or by ion implantation followed by either thermal annealing or subsequent additional irradiation. Different methods for the formation of novel structural relationships between embedded nanocrystals and their hosts have been developed, and the results presented here demonstrate the general flexibility of ion implantation and irradiation techniques for producing unique near-surface nanocomposite microstructures in irradiated host materials.
Study of the Crystallization of Nanoporous Mixed Metal Oxide Phases
Adsorption Science & Technology, 2008
A systematic study of the synthesis and characterization of pristine ceria and of mixed cerium/metal oxides has been undertaken. Various synthetic routes were explored, with the crystallization process being examined via thermal analysis, XRD and electron microscopy. It was shown that even when multiple phases were generated upon heat treatment, mixed phases were also generated. However, the presence of organic molecules during the syntheses, as matrices, solvents or precipitating bases, had a profound effect upon the surface texture of the samples prepared.
Synthesis of Radioactive Nanostructures in a Research Nuclear Reactor
2016
In this work, the synthesis of radioactive nanostructures by water radiolysis was studied. The irradiation processes were done in the Missouri University of Science and Technology research nuclear reactor (MSTR). Radioactive gold nanoparticles (AuNPs) were synthesized from aqueous solutions containing the metal salt precursors by radiolysis of water. Seven different samples were irradiated at 200kW of thermal power for 0.5, 1, 3, 5, 10, 30, and 60 minutes. The average sizes of the obtained nanoparticles ranged from 3 nm to 400 nm, it was found that the particle size decreased with the irradiation time. Some agglomerations of particles were found in each solution after the irradiation process. With this research, it was possible to synthesize, in a single step, radioactive AuNPs with the appropriate characteristics to be used in imaging diagnosis and cancer radiation therapy. Radioactive bimetallic nanoparticles of silver and gold (Au/Ag BMNPs) were synthesized from aqueous solutions containing the metal salt precursors by radiolysis of water. Four samples with different Au/Ag concentration (30/70, 50/50, 70/30, and 0/100 by volume percentage) were irradiated at 10kW of thermal power for 3 minutes. The obtained nanoparticles showed (Au)core-shell(Ag) structure as well as alloyed metal structure depending on the solution concentration. It was found that the alloyed metal nanoparticles presented a faced centered cubic crystal structure with lattice parameter of 4.082 0.001 Å and a chemical composition of 70.21 0.01 wt% Au and 28.59 0.01 wt% Ag. v ACKNOWLEDGMENTS My completion of this Master degree could not have been accomplished without the support of my advisor Dr. Carlos H. Castano Giraldo; I must express my gratitude for his guidance, patience, and motivation to develop this research. I would also like to thank the members of the Committee Dr. Joshua P. Schlegel and Dr. Joseph D. Smith whom were involved in this work, I am thankful for their very valuable comments on this thesis and for their participation during my final defense. In addition, I really appreciate the support and help of Dr. Safwan Jaradat during the simulation process, and the support, help and friendship of my special friend, Lucy Sutcliffe, who has taught me valuable things during my learning time. This thesis could not have been done without the funding opportunities from
A review on radiation-induced nucleation and growth of colloidal metallic nanoparticles
Nanoscale Research Letters, 2013
This review presents an introduction to the synthesis of metallic nanoparticles by radiation-induced method, especially gamma irradiation. This method offers some benefits over the conventional methods because it provides fully reduced and highly pure nanoparticles free from by-products or chemical reducing agents, and is capable of controlling the particle size and structure. The nucleation and growth mechanism of metallic nanoparticles are also discussed. The competition between nucleation and growth process in the formation of nanoparticles can determine the size of nanoparticles which is influenced by certain parameters such as the choice of solvents and stabilizer, the precursor to stabilizer ratio, pH during synthesis, and absorbed dose.
Radiation-Assisted Formation of Metal Nanoparticles in Molten Salts
The Journal of Physical Chemistry Letters
Knowledge of structural and thermal properties of molten salts is crucial for understanding and predicting their stability in many applications such as thermal energy storage and nuclear energy systems. Probing the behavior of metal contaminants in molten salts is presently limited to either foreign ionic species or metal nanocrystals added to the melt. To bridge the gap between these two end states and follow the nucleation and growth of metal species in molten salt environment in situ, we use synchrotron X-rays as both a source of solvated electrons for reducing Ni 2+ ions added to ZnCl 2 melt and as an atomic-level probe for detecting formation of zerovalent Ni nanoparticles. By combining extended X-ray absorption fine structure analysis with Xray absorption near edge structure modeling, we obtained the average size and structure of the nanoparticles and proposed a radiation-induced reduction mechanism of metal ions in molten salts.
Colloidal systems for crystallization processes from liquid phase
CrystEngComm, 2013
Colloidal systems are involved in crystallization processes in many different ways: on one hand, colloids may be used as controlling or structure-directing agents, as nanoreactors and as scaffolds and templates for crystallization. On the other hand, it is very often desirable to obtain colloidal particles in a crystalline or nanocrystalline state. In this highlight, we cover the challenges and the recent advances on the following topics: (i) the use of polymer colloids as additives for crystallization due to their ability to control nucleation and growth and even to promote enantiomer resolution by enantioselective crystallization; (ii) state of the art in the preparation of inorganic crystalline colloids; and (iii) the application of colloidal systems (i.e., colloidal particles, droplets, micelles and vesicles) as supports, templates and nanoreactors for inorganic crystallization.