Gravitational Annealing of Colloidal Crystals
  A silica colloidal crystal obtained by centrifugation at 9 G for 2 days in water was annealed by additional stronger centrifugation at 50 G for 5 days. The number of the striations observed in the colloidal crystal under crossed polarized light decreased at some parts in a growth container after additional centrifugation, while the number alse increase at the other parts. The decrease probably shows the shrinkage of the stacking disorders under high gravity, while the increase probably shows the production of new stacking disorder. 
Yoshihisa Suzuki, Jin Endoh, Atsushi Mori, Tomoki Yabutani, Katsuhiro   Tamura
cond-mat.soft cond-mat.mtrl-sci