Electric Field Induced Agglomeration of Nearly Ferroelectric   Superconducting YBa2Cu3O7-d Powders
  We report on the effect of agglomeration forced by strong electric field in fine particles of nearly ferroelectric YBa2Cu3O7-d superconductor. It turns out that the particles from agglomerates exhibit different morphology than the rest of powder that attaches to high-voltage electrodes. Study by means of electron paramagnetic resonance revealed in the powder attached to electrodes a narrow spectrum superimposed on Cu2+ anisotropic spectrum common for YBa2Cu3O7-d superconductors. We assume that this narrow spectrum originates from nanopolar regions generated by strong electric discharges taking place during the experiment. Consequently, the effect of agglomeration can be explained in terms of electrostatic interactions between the particles containing nanopolar regions with strong electric dipolar moments. 
B. Andrzejewski, W. Bednarski, K. Chybczynska, A. Hilczer, M. Matczak,   F. Matelski
cond-mat.supr-con