Epitaxial growth and high critical current density of BHO-doped YBCO/STO composite films

BaHfO₃ (BHO)-doped YBa₂Cu₃O_7−x (YBCO) films have been fabricated on SrTiO₃ (STO) microarray-buffered LaAlO₃ (100) (LAO) substrates by photosensitive sol–gel lithography (PSGL) and chemical solution deposition (CSD). This approach involved the incorporation of secondary-phase additions and substrate decoration to enhance the epitaxial growth of the composite films (YBCO + BHO/STO). The microstructure and texture of YBCO + BHO/STO composite films were analyzed by atomic force microscopy (AFM), optical microscopy (OM), scanning electron microscopy (SEM), and X-ray diffractometer (XRD). The results indicated that the STO microarray interface improved the surface microstructure of the BHO-doped YBCO film and enhanced the in-plane and out-of-plane texture of YBCO films with a high BHO content. Under the influence of STO microarray, a high content of BHO particles could serve as effective flux-pinning centers within the YBCO matrix, leading to a substantial increase in the critical current density under magnetic fields. The YBCO + 10%BHO/STO film exhibited a high critical current density (J_c) of 3.86 MA/cm² at 77 K in a self-field, with maximum pinning force values of 5.4 GN/m³ at 77 K and 39.8 GN/m³ at 50 K, respectively. Therefore, the incorporation with the STO microarray buffer was a viable method for enhancing film texture and introducing effective artificial centers to boost superconductivity performances.