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E u r o s c i c o n C o n f e r e n c e o n
Physical Chemistry and
Analytical Separation Techniques
Journal of Organic & Inorganic Chemistry
ISSN: 2472-1123
October 08-09 , 2018
Amsterdam, Nether l ands
Physical Chemistry and Analytical Separation Techniques 2018
Page 16
C
olloidal suspensions are model systems to study phase transformations
of first order as crystallization of a liquid system. The particles of colloidal
suspensions are in size of several hundred nanometres and the carrier fluid is
transparent in the spectrum of visual light. These characteristic features make
colloidal suspensions easily accessible for optical investigations. The structural
transformations are very sluggish and can be monitored in-situ. In the present
work, light scattering experiments are performed to investigate homogeneous
nucleation in the interior and heterogeneous nucleation on the container walls of
silica colloidal suspensions and tomeasure thegrowth velocity of the crystal. Since
nucleation processes require short-range ordering as precursor of their formation,
we conduct ultra-small-angle scattering of X-rays of synchrotron radiation at DESY
Hamburg todetermine the topological short-range order ofmonodisperse colloidal
suspensions in liquid phase far away from thermodynamic equilibrium. In such a
way, the entire pathway of crystallization from the stable liquid to the metastable
liquid state, the formation of short-range ordering over crystal nucleation and
eventually crystal growth is quantitatively investigated. The experimental results
are analysed within current models of formation of aggregates of different
structure, classical nucleation theory and the Wilson-Frenkel theory of crystal
growth. From measurements of crystal growth and its analysis within the Wilson-
Frenkel theory, the deviation from thermodynamic equilibrium of a shear melted
crystal is inferred as defined by the difference of chemical potential between the
metastable liquid and the stable solid. The in-situ investigations of homogeneous
crystal nucleation are used to determine the solid-liquid interface which is very
difficult to measure by other methods. The measurement of the growth of a planar
liquid-solid interface allows for detailed information of the particle attachment
kinetics of particles from the liquid to the crystal
Short range order, crystal nucleation and
crystal growth in liquid colloidal suspensions
Dieter M Herlach
1, 2, 3
1
Institut für Materialphysik im Weltraum DLR, Germany
2
Institut für Experimentalphysik IV, Ruhr-Universität Bochum, Germany
3
Otto-Schott Institut für Metallische Werkstoffe, Friedrich-Schiller-
Universität, Germany
Dieter M Herlach, J Org Inorg Chem 2018 Volume: 4
DOI: 10.21767/2472-1123-C6-016
Biography
Dieter M Herlach has studied Physics at the RWTH Aachen
University and has received the Doctoral degree as
Doctor rerum
naturalium
from the same university. He was Group Leader at
the Institute of Materials Physics in Space and Senior Scientist
of the German Aerospace Center DLR. He is Full Professor in
Physics at Ruhr-Universität Bochum (RUB). He has authored
over 300 scientific publications in refereed journals and served
as Editor of six books. He educatedmore than 30 PhD students.
He lead projects of the German Research Foundation, the
German Aerospace Center-Space Management, European
Space Agency and was Principal Investigator of NASA during
three spacelab missions. He initiated and coordinated two
priority programs of the German Research Foundation (DFG),
He is Honorary Professor of three universities. He chaired the
Division of Metal and Materials Physics of the German Physical
Society DPG, and was an Elected Member of the council of
DPG, General Review Committee of DFGand Deputy Chairman
of the German Society of Materials Science and Engineering.
dieter.herlach@dlr.de