  We successfully fabricated large grains of silica colloidal crystals in an
inverted-triangle internal-shaped container (inverted-triangle container) by
centrifugation. The largest grain in the container was much larger than that in
a container which has a flat bottom and constant width (flat-bottomed
container). The edged bottom of the inverted-triangle container eliminated the
number of the grains, and then the broadened shape of the container effectively
widened the grains.
