POLYDISPERSE SUSPENSIONS OF BATIO3-PARTICLES

Stable suspensions of small BaTi03-particles in hydrocarbon carrier liquids were produced by long milling processes. The particle size is determined from the diffusive motion of the particles using dynamical light scattering techniques. The size distribution is obtianed by accurate evaluation of the autocorrelation function of the scattered radiation The electro-optical Kerr-rotation is measured both stationary and time -resolved. The field-induced birefringence suggests a cutt-off-radius of ≈ 20nm for the size distribution, separating the small particles, which carry a permanent dipole moment from the large ones, which are compensated. For the relaxation of the birefringence, the Brownian rotational relaxation is found to be responsible. © 1990, Taylor & Francis Group, LLC. All rights reserved.