Research On Preparation Of CeO₂ And HZO Buffer Layer On IBAD-MgO Substrate

The discovery of superconductivity has been recognized as one of the greatest scientific achievements of 21 th century. In 1986, the discovery of high-temperature superconductivity（HTSC）, which has the 100 times larger current carrying capacity than copper wire with the same cross-section, got extensive attention. All of the superconducting products, such as cable, superconducting power syste m, have small size, light weight, high efficiency, low energy consumption, and large capacity. Comparated with the firstly genetation Bismuth-based superconductor, the secondly genetation YBCO superconductor has higher irreversible field and lower cost, which has been the major commercial superconducting materials. Based on the fabrication and properties of oxide buffer layer and superconducting layer in YBCO coated conductor, this paper does some research on the following three aspects:Firstly, we systematically studied effect of deposition condition, such as IBAD-MgO texture, substrate temperature and thickness, on the orientation and in-plain texture of CeO₂ layer. CeO₂ layer was directly prepared on the IBAD-MgO substrate by PLD, and YBCO superconducting layer was fabricatied by PLD. Under the optimal condition, the CeO₂ layer had pure c-axis orientation and high in-of-plane texture degree of 2.9°.The critical current density of YBCO layers deposited directly on CeO₂ films is 6.25×106 A/cm2 at 77 K and self field.Secondly, we firstly fabricated Ho₂Zr₂O₇（HZO） film on the metal IBAD-MgO substrates by radio- frequency（RF） magnetron sputtering, and relationships between substrate temperature, sputtering power and microstructure of HZO layer were also investaged. The HZO buffer layer had smooth surface and good texture. Then we prepared YBCO superconducting layer using PLD method on the HZO buffer layer. The critical current density of YBCO layers is 2.76×106A/cm2 measured at 77 K in self field, which proved the HZO buffer film is suitable for the YBCO film epitaxial growth.Thirdly, we investigated the superconducuting properties of YBCO films in magnetic field. We fabricated the YBCO film on the CeO₂ /IBAD-MgO buffered Hastelly tapes, and studied the effect of preparation condition on the superconducting properties in magnetic field. It found that with increasing magnetic field intensity the critical current decreased in exponential decay, and anisotropy. And the trend had no matter with the preparation condition. But the critical current and the degree of anisotropy would change with the preparation condition.In conclusion, we fabricated CeO₂ and HZO buffer layers with pure c-axis oriented and smooth surface. It proved that the CeO₂ and HZO buffer layers were totally suitable for the fabrication of high quality YBCO coated superconductor. The YBCO film epitaxial grown on the PLD-CeO₂ buffered IBAD-MgO tapes, which had critical current of 6.25×106A/cm2 at 77 K and self field, reached the advanced world level and had good performance in magnetic field.