Abstract
The activation field α of barium titanate single crystals has been measured over a range of thicknesses from 350 μ to 4 μ using liquid electrodes. From these measurements it has been deduced that barium titanate has a surface layer of layers with a total thickness of 25±5 μ. The activation field of the bulk material is 5 kV/cm and that of the surface layer is 15±5 kV/cm.