Nanotubes Made from Deeply Undercooled Cryolite/Alumina Melts

d ) Institute of Physics, Slovak Academy of Sciences, Dubravska cesta 9, SK-845 36 Bratislava e ) Instituto de Ciencia de Materiales de Aragon, CSIC-University of Zaragoza, ES-50009 Zaragoza The rapid-solidification processing (by a cooling rate of 105 -1 06 K/s) was used for the preparation of deeply undercooled cryolite/alumina (Na3AlF 6/Al2O3) melts. We found a mass of nanotubes on the surface of these undercooled melts. The nanotubes were preferentially located on the defect places of the surface with the following approximate dimensions: base � 100 � 100 nm, length � 1000 nm. The solidified samples with the nanotubes on the surface were analyzed by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), and infrared spectroscopy (IR).