BaZrO₃ insulation coatings for HTS coils

Barium zirconium oxide (BaZrO₃) thick films were grown on Ag and AgMg sheathed Bi₂Sr₂CaCu₂O_8+δ (Bi-2212) superconducting tapes for electrical insulation purposes. A BaZrO₃ (BZO) precursor solution was prepared by sol-gel synthesis using Ba and Zr based alkoxide. Reel-to-reel continuous sol-gel dip coating method was used to grow BZO coatings on superconducting tapes. Processing, microstructure and electrical properties of high temperature BZO insulation coatings have been studied. The BZO coatings were grown in the temperature range of 450 and 600 °C in air. ESEM and X-ray diffraction were used to investigate microstructure and crystallinity of the coatings. Room temperature resistance, dielectric constant, and high voltage breakdown strength of the coatings were measured to be 13 MΩ, 22.5 and 1.0 kV at 1.5 mA, respectively.