  In a previous study, structure of silica gels prepared in a high magnetic
field was investigated. While a direct application of such anisotropic silica
gels is for an optical anisotropic medium possessing chemical resistance, we
show here their possibility of medium in materials processing. In this
direction, for example, silica hydrogels have so far been used as media of
crystal growth. In this paper, as opposed to the soft-wet state, dried silica
gels have been investigated. We have found that lead (II) nanocrystallites were
formed induced by electron irradiation to lead (II)-doped dried silica gels
prepared in a high magnetic field such as B = 10 T. Hydrogels made from a
sodium metasilicate solution doped with lead (II) acetate were prepared. The
dried specimens were irradiated by electrons in a transmission electron
microscope environment. Electron diffraction patterns indicated the
crystallinity of lead (II) nanocrystallites depending on B. An advantage of
this processing technique is that the crystallinity can be controlled through
the strength of magnetic field B applied during gel preparation. Specific
skills are not required to control the strength of magnetic field.
