Preparation of Bi-2212/YBCO heterostructure and their interfacial characters

YBa_(2)Cu_(3)O_(7‐x)(YBCO)thin films were prepared on LaAlO_(3)(LAO)substrates by a sol–gel method,and the epitaxial growth of Bi‐2212 thin films on YBCO thin films was investigated.Both YBCO and Bi_(2)Sr_(2)Ca1Cu_(2)O_(8)+δ(Bi‐2212)bilayer films exhibit good biaxial texture and superconducting properties.Afterward,a cross‐shaped Bi‐2212/YBCO heterostructure was fabricated,and its interfacial atomic arrangement and I‐V characteristics were analyzed.Atomic‐resolution STEM images obtained from a spherical‐aberration‐corrected transmission electron microscope show that two superconducting films exhibit a layered structure and the atoms inside the films are artfully arranged.Moreover,the order of the seven atomic layers between Bi‐2212 and YBCO layers with a thickness of about 1.32 nm is misarranged.Among them,the Y‐O layer of YBCO and the Sr‐O layer of Bi‐2212 share a CuO_(2) layer.The I‐V curves of Bi‐2212/YBCO bilayer films show that the seven misarranged atomic layers at Bi‐2212/YBCO interface acts as a barrier layer,which means that a Josephson junction can be fabricated using this interface characters.

Fabrication of YBCO superconducting microarray by sol-gel process using photosensitive metal chelates

We used yttrium acetate, barium acetate, and copper acetate as the starting materials, benzalacetone (BzAcH) as chemical modifier, and methanol (MEOH) as solvent to synthesize a stable fluorine-free YBCO precursor sol. The coated YBCO gel film using this precursor sol exhibited photosensitivity to UV irradiation at a wavelength of 330 nm. After the subsequent exposing, the YBCO gel film showed a decreased solubility in several organic solvents. Based on the photosensitivity of the YBCO/BzAcH gel film, YBCO superconducting microarray with the pitch of 5 μm was fabricated by irradiating the gel film with UV light through a mask, followed by leaching the unirradiated area in a mixture solvent of methanol and n-butyl alcohol with the volume ratio of 1:1. After proper heat treatment the x-ray diffraction result showed that the as-prepared arrays were highly c-axis oriented and with a high T c by this new photosensitive sol-gel process.