The interaction between two spheres in silicone oil under an electric field

The attraction force between two spheres (single crystal SrTiO3 spheres and SrTiO3-coated metal spheres) in silicone oil under an electric field is measured and calculated. The dependence of the force on the field strength and interspherical distance is given. The interaction force of SrTiO3-coated metal spheres is much larger than that of SrTiO3 spheres at a small interspherical gap.