New stabilizers and the search for higher solid volume fractions of nm-BaTiO/sub 3/ particles suspended in hydrocarbon carrier liquids

Polydisperse suspensions of BaTiO/sub 3/ particles prepared by milling in a ball mill have been characterized by quasi-elastic light scattering. A significant phase shift between the stimulating field and the Kerr signal is observed. The observed effects are explained by assuming a very thick surfactant layer (of about 10-20 nm) around the BaTiO/sub 3/ particles. This is capable of explaining the phase shift because of the very high rotational relaxation constant of such large particles; then the phase shift is on the same scale as the relaxation time-constant. This can also explain the dependence of the Kerr effect on the peak value of the electric field, because the effective relaxation time decreases with increasing field strength.