Applying a strong static DC electric field to supersaturated aqueous
glycine solutions resulted in the nucleation of the .gamma. polymorph
attributed to the electric-field induced orientation of the highly polar
glycine molecules in large preexisting solute clusters, helping them
organize into a crystalline structure. A method to induce crystallization
and to prepare polymorphs and/or morphologies of materials by using a
static electric field to cause nucleation and crystal growth to occur in
a supersaturated solution in such a way as to obtain a crystal structure
that would not normally appear without the use of the static electric
field. Aqueous glycine solutions were prepared by combining solid glycine
and water. Supersaturated solutions were generated by heating the tubes
to 62-64.degree. C. and holding them at that temperature in an
ultrasonicator overnight. Once the glycine was completely dissolved, the
solutions were slowly cooled to room temperature. A chamber was
constructed consisting of two brass electrodes separated by a 5 mm
insulating gap, with a hole drilled down through the center, parallel to
the gap-electrode interface, with a diameter large enough to accommodate
the test tube. A DC voltage was applied across the electrodes, large
enough to produce electric fields in the range of 400,000 to 800,000 V/m.
Tests tubes containing the aged solutions were placed in the high-voltage
chamber. Exposure of the aged solutions to fields of 600,000 V/m resulted
in crystallization typically within 30-90 min. The onset of nucleation
was observed visually by the formation of a needle-shaped crystallite.