Foreign Cooperating Institutions - Institute of Inorganic Chemistry ...

High temperature liquids: Nanotubes formed from rapidly cooled
melts of alumina saturated cryolite
M. Kucharík, M. Korenko, B. Kubíková, F. Šimko
So-called Rapid Solidification Processing (RPS) was used to obtain more information on
the structure of deeply undercooled cryolite-alumina melts. It involved a rapid quenching of
the melt by cooling rate of ~10 6 K.s -1 . The RSP is more frequently used in a different field of
material engineering - for preparation of special amorphous materials such as glassy metals of
interesting properties. Cryolite and alumina are the main constituents of the electrolytes in the
industrial production of aluminium by the Hall-Héroult process. SEM analysis has shown an
additional feature of RPS application. The mass of nanotubes on the surface of so prepared
undercooled melts mainly on the randomly shaped aggregates was observed. These nanotubes
having usually a square shape in cross-section were preferentially located on the defect places
of the surface with approximate dimensions of the base ~100 x 100 nm and the length ~1000
nm. HR-TEM and EDX analyses of a lamella cut out of the prepared aggregates indicated that
cryolite alone formed these nanotubes. However, alumina evidently played some role in the
process of crystallization of the nanotubes since no similar features were observed on the
surface of pure cryolite samples. Further investigation is in progress.
Nanotubes formed from rapidly cooled melts of alumina saturated cryolite
Further information: M. Korenko: michal.korenko@savba.sk
Korenko M., Kucharík M., Vincenc Oboňa J., Janičkovič D., Córdoba R., De Teresa J.M., Kubíková
B.: Helv. Chim. Acta 91, 1389-1399, 2008
16