Pyroelectric investigation of the surface polarization in the isotropic phase of a nematic liquid crystal

Measurements of the temperature dependence of the pyroelectric coefficients in cells with homeotropic and planar boundary conditions were performed in order to study the surface polarization and determine its nature in the is otropic phase of a nematic liquid crystal. Analysis of these data establish ed that the ordering polarization arising as a result of the nonuniformity of the order parameter in the near-boundary region of the liquid crystal an d the polar monolayer due to the bifilar properties of the molecules of the liquid crystal at the boundary with the solid wall of the cell are respons ible for the surface polarization in the isotropic phase of a nematic liqui d crystal. The values of the pyroelectric coefficients of monolayers and th e coefficients of the ordering polarization for planar and homeotropic orie ntations are estimated. (C) 2000 MAIK "Nauka/Interperiodica".