Crystal growth in materials scienceT
Non-classical nucleation and crystallization
Non classical nucleation and non classical crystallization are additional and recently discovered pathways for nucleation or particle based crystal formation, which are not covered by textbook knowledge. Increasing evidence for such non-classical mechanisms is reported. The aim of this symposium is to catch the cutting edge research in this rapidly developing field.
Crystal nucleation and growth is fundamental, and relevant to many fields of science and technology, including materials science and technology, chemistry and chemical engineering, metallurgy, nanoscience and mineralogy. This has initiated decade long intense research but even after 80 years of crystallization research, neither nucleation nor crystallization are fully explored and understood yet. In the last decade evidence for particle based crystallization pathways was found from the study of Biominerals, which are highly optimized minerals formed by living organisms. These so called non-classical crystallization mechanisms are based on self-assembly or ligand-directed assembly of well-aligned small nanoparticles, which can produce so-called mesocrystals with quasi-single crystal characteristics which are built up from aligned nanoparticle building units. These mesocrystals can further transform to single crystals via synergetic oriented attachment of the small nanoparticles. Oriented attachment is the mutual alignment of nanoparticles in crystallographic register usually followed by crystallographic fusion of the nanoparticles eliminating two crystal faces and thus reducing surface energy.
In addition to non-classical crystallization, already nucleation can proceed along non-classical pathways. These involve so called pre-nucleation clusters, which are stable and form nuclei by aggregation. Importantly, pre-nucleation clusters are already present in under saturated solution. Therefore, they present new options for nucleation and its control.
To advance knowledge in the field of non classical nucleation and crystallization, this symposium will cover both fundamental and applied studies in materials from the nano to the micron range produced produced via these non-classical nucleation and crystallization pathways. The symposium will focus on (1) theoretical and experimental investigations of non-classical nucleation (2) synthesis and characterization of materials via Oriented Attachment and mesocrystal routes, (3) properties and applications of materials from non-classical crystallization reactions; (4) computational and theoretical studies of non-classical crystallization (5) experimental mechanistic studies of nonclassical nucleation and crystallization.
Hot topics to be covered by the symposium:
- Non classical Nucleation - theoretical and experimental advances
- Oriented Attachment - theory, synthesis, applications and properties
- Mesocrystals - theory, synthesis, applications and properties
- Experimental advances to study non-classical nucleation and crystallization
- New Materials via non-classical nucleation and crystallization
List of invited speakers (confirmed):
- Viveka Alfredsson, Lund University
- Henrik Birkedal, Aarhus University
- Denis Gebauer, University of Konstanz
- Wolfgang Tremel, University of Mainz
- Roland Kröger, University of York
University of Konstanz
Phone: +49 7531 884063
Fax: +49 7531 883139
Laboratory for Multifunctional Materials
Phone: +41 44 633 63 90
Fax: +41 44 633 15 45
Department of Materials and Environmental Chemistry
Phone: +46 8 162368
Fax : +46 8 152187
|Start at||Subject View All||Num.||Add|
Nucleation in amorphous materials : Markus Niederberger
Authors : Henrik Birkedal
Affiliations : iNANO & Department of Chemistry, Aarhus University, 14 Gustav Wieds Vej, 8000 Aarhus, Denmark; email@example.com
Resume : Amorphous precursor phases are widespread in the formation of many crystalline materials, in particular in biomineralization as in apatite (bone) and calcium carbonate (shells etc) biomineral formation. However, the underlying chemical mechanisms and kinetics of crystallization from amorphous phases remain unclear. In situ X-ray diffraction provides unique insights into crystallization of nanocrystalline systems. It yields information on the amount of crystalline material but also on the crystallite size and shape as well as lattice deformation . Water solvent is challenging due to its the large scattering signal. Nevertheless, it is possible to extract information on the amorphous precursor phase and at the same time the progress of crystallization. I will discuss the formation of apatite from amorphous calcium phosphate (ACP) in water. Varying pH changes the speed of reaction as well as crystal morphology. The choice of phosphate counter ion is found to be crucial: Na+ and K+ lead to significantly different behaviors because Na+ allows incorporation of carbonate from air into the lattice while K+ does not. We study the impact of additives on apatite formation. Carbonate is found to strongly impact apatite formation from mixed ACP/ACC. These studies provide detailed insights into crystallization that are likely to lead to rational design of additives for formation of novel functional materials.
Authors : A. Carretero-Genevrier1, M. Gich2, L. Picas3, J. Gazquez2, J. Oró-Solé2, G.L. Drisko4, D. Grosso4, E. Ferain5, T. Puig2, X. Obradors2 ,C. Sanchez4, J. Rodriguez-Carvajal6, N. Mestres2
Affiliations : 1Institut des Nanotechnologies de Lyon (INL) CNRS- Ecole Centrale de Lyon, 36 avenue Guy de Collongue, 69134 Ecully, France. 2Institut de Ciència de Materials de Barcelona ICMAB, Consejo Superior de Investigaciones Científicas CSIC, Campus UAB 08193 Bellaterra, Catalonia, Spain 3UMR 144, Institut Curie, 12 Rue Lhomond, 75005,Paris, France 4Laboratoire Chimie de la Matière Condensée, UMR UPMC-Collège de France-CNRS 7574. Collège de France, 11 place Marcelin Berthelot, 75231 Paris, France. 5Institute of Condensed Matter and Nanosciences, Bio & Soft Matter (IMCN/BSMA), Université Catholique de Louvain, Croix du Sud 1,1348 Louvain-la-Neuve, Belgium, and it4ip s.a., rue J. Bordet (Z.I. C), 7180 Seneffe, Belgium 6Institut Laue-Langevin, 6 rue Jules Horowitz, BP 156, 38042 Grenoble Cedex 9, France
Resume : The integration of quartz on silicon in thin film form is a challenging issue due to the differences in the crystal structures of these materials. In this regard, this work overcomes the main challenges for the integration of novel functional oxide materials on silicon including (i) epitaxial piezoelectric α-quartz thin films  and (ii) 1D single crystalline phases of manganese oxides that share common growth mechanisms [2,3]. The aim of this contribution is to discuss in detail the non classical nucleation and crystallization mechanisms of these materials grown from chemical solutions. Quartz films are crystallized by a confined devitrification of amorphous silica films assisted by a heterogeneous catalysis driven by alkaline earth cations present in the precursor solution. The films are made of perfectly oriented individual crystallites epitaxially grown on (100)-Si. The active influence of the Si substrate mediates the preferential orientation of crystal nuclei, yielding competitive growth and producing a columnar microstructure. Quartz films are piezoelectric and can be used as template for the epitaxial growth of manganese oxide nanowires on silicon. This methodology exhibits a great potential for the design of novel oxide compounds on silicon with unique properties.  A. Carretero-Genevrier et al. Science 340, 827 (2013);  A. Carretero-Genevrier et al. Chem.Mater. 10.1021/cm403064u (2013)  A. Carretero-Genevrier et al. Chem.Soc.Rev. 10.1039/C3CS60288E (2013)
Posters : Helmut Cölfen
Authors : Guoli Fan, Jing Kang, Feng Li
Affiliations : State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029, P.R.China.
Resume : Recently, substantial attention has been focused on the preparation of porous metal oxides because of their wonderful physicochemical properties and wide potential applications in the areas of catalysis, sorption, chemical and biological separation, photonic and electronic devices, and drug delivery [1, 2]. In the present work, a series of high-surface-area and porous tetravalent metal oxides (TiO2, CeO2, ZrO2) were successfully synthesized using the colloid mill and hydrothermal technique. The key features of this unusual method are a very rapid mixing of reactants and nucleation process in a colloid mill followed by a separate aging process in the presence of NaBH4. Furthermore, the extreme forces to which the nucleation mixture is subjected in the colloid mill prevent aggregation of the nuclei and result in the nuclei having a uniform small size, while NaBH4 added can further induce the formation of porous metal oxide framework. As a result, this approach for the nucleation and crystallization endows a series of tetravalent metal oxides with high surface area, small crystallite size and narrow pore size distribution, which might provide a new platform for the preparation of advanced functional metal oxide materials. Reference  X. Wang, D.P. Liu, et al., J .Am. Chem. Soc. 135 (2013) 15864-15872.  E. Ortel, S. Sokolov, et al., Chem. Mater. 24 (2012) 3828-3838
Authors : VB Vorontsov, V.K.Pershin , AS Cherepanov
Affiliations : Department «Physics and Chemistry» URALS STATE UNIVERSITY of RAILWAY TRANSPORT
Resume : Investigation of the structural relationship of the liquid and solid phases during the formation of Al single crystals on the basis of analysis of AE signals VB Vorontsov, V.K.Pershin , AS Cherepanov Department «Physics and Chemistry» URALS STATE UNIVERSITY of RAILWAY TRANSPORT The results of these and our previous studies [1,2 ] are devoted to the interpretation of the acoustic emission signals AE observed during phase transitions of type II . Emission AE signals during solidification accompanies crystallization of substances having a crystalline structure , therefore the laws of phase transitions from solid to liquid and back on the model material will be repeated in the main terms on any material of given crystalline structure and structure-sensitive properties of substance. In this paper, as a model substance Al ¬ 99,999 is used. Acoustic signals recorded during the experiment, were subjected Fourier analysis of the main parameters : amplitude A, frequency , separate signal energy E , Σ E of all signals . Given the fact that the method of Fourier analysis is a universal one and differs high sensitivity we decided to apply it to study the kinetics of processes in the melt and at the interface by changing its temperature in the direction of increasing and decreasing from t = 860 ° C to the point of crystallization. The task of the study included: a) analysis of the spectral composition of AE signals and establishing energy connection of all AE signals , with the change of temperature conditions in the melt . b) the study of the nature of AE signals and their manifestation of kinetics process of isothermal heating and cooling of the melt. As a result , on the basis of experimental data , we supposed that in the melt when overheated to t = 800 ° C areas with short-range order of atoms or (clusters) are retained but their size and number are changed during the heating. Prepared integral response melt its structural changes as a reaction to the total energy of these signals with AE melt incrementally heated to 860 ° C and cooled to the crystallization point at the same rate. A correspondence between the dynamics of clusters landing at the interface during the growth of single crystal and generated acoustic signals was set. References 1. V.B.Vorontsov ,V.V. Katalnikov Relationship between acoustic emission during phase transitions of the melt-solid body and the structure of the melt of metallic systems. Proceedings of the Russian Conference Structure and Properties of Metal and Slag Melts. V. 4. 2004. p. 12. 2 . V.B Vorontsov, D.V.Zhuravlev, J.Chem.Chem.Eng.6 2012 p. 358.
|Start at||Subject View All||Num.||Add|
Authors : Wolfgang Tremel, Michael Dietzsch, Filipe N. Natalio, Stephan E. Wolf
Affiliations : Johannes Gutenberg Universität, Institut für Anorganische Chemie, 55099 Mainz, Germany
Resume : The formation of calcium carbonate has been studied for more than a century with more than 3000 papers over the past 10 years. Much attention has been devoted to amorphous calcium carbonate (ACC) as a singular non-equilibrium phase, because there is increasing evidence that this phase plays a crucial role in biomineralization. Many mineralization processes are now believed to occur through the transformation of a transient amorphous precursor, which has been shown to act a reactive in intermediate in generating complex functional materials. We have studied the effect of proteins like ovalbumin, lysozyme and silicatein, which are present in the first stage of egg shell formation or in the formation of siliceous spicules of sponges, on the homogeneous formation of the liquid-amorphous calcium carbonate (LACC) precursor, by a combination of complementary methods like in situ WAXS, light scattering, TEM and cryo-TEM . Lysozyme destabilizes the LACC emulsion, whereas the glycoprotein ovalbumin extends the lifetime of the emulsified state. We demonstrate ovalbumin to act as a stabilizer for a polymer-induced liquid precursor (PILP) process. Ovalbumin is assumed to play a key role during eggshell formation where it serves as an effective stabilization agent for transient precursors and prevents undirected mineralization of the eggshell. Emulsified LACC carries a negative surface charge and is stabilized electrostatically. We propose that the liquid amorphous calcium carbonate is
No abstract for this day
No abstract for this day
No abstract for this day