Silicone rubber compositions with yttrium-doped ceramics for outdoor insulation

In this work, the effect of barium titanate (BaTiO₃) powder doped with yttrium (Y) when used as filler in silicone rubber was studied. Y³⁺ ions replace the Ba²⁺ ions in the BaTiO₃ crystal lattice in a concentration of 0.4 at.% using a thermal treatment at 1300°C during 1 hour. The dielectric constant of this ceramic powder (K=692) is almost five times bigger as compared to pure BaTiO₃ (K=154). This powder was incorporated to the silicone matrix in a 40 vol.% obtaining a good dispersion but the dielectric constant of the composite is not greatly increased (K=10.61); however, its electrical conductivity is decreased compared to a pure BaTiO₃ composite prepared with the same conditions. Electric field simulations were performed considering the properties of the obtained composites at power frequency and under impulse voltage for a bushing and a long rod insulator.