Optimization of annealing parameters for the growth of epitaxial Ba2YCu3O7−x films on LaAlO3(100)

Abstract

The superconducting and structural properties of Ba2YCu3O7−x (BYCO) films on LaAlO3(100) substrates can be improved by carefully optimizing the post-deposition annealing parameters. Films are grown by co-deposition of BaF2, Y, and Cu in the correct stoichiometric ratio to within 1% of 2:1:3. Annealing parameters in an ex situ furnace, including the ambient, annealing temperature, oxidation temperature, and duration of anneals are systematically studied. Films are characterized for epitaxial quality (χmin), morphology, critical temperature (Tc), sharpness of the superconducting transition (ΔT), and critical current density (Jc). For example, beyond simply dissociating BaF2, the use of wet O2 appears to prevent the agglomeration of oxides during the initial heating process, and then act to thermodynamically stabilize the basic BYCO film structure at high temperatures after being formed. Comparisons are made with the best single-crystal BYCO structural and electrical data available. The optimized films have relatively smooth morphology with χmin<3%, Tc>90 K, ΔT<0.5 K, and Jc>106 A/cm2 in essentially zero magnetic field at 77 K.

All solution-chemistry approach for YBa2Cu3O7−δ-coated conductors

“…19 The BaF 2 -process conditions are described in detail elsewhere. 20,21 The typical thickness of each sol-gel layer is 100-200 nm. Figure 1 is an x-ray diffraction -2 scan from Cu K␣ radiation for a YBCO/STO/Ni͑100͒ sample ͑100 nm thick YBCO on 500 nm Nb:STO͒.…”

Annealing assisted substrate coherency and high-temperature antiferromagnetic insulating transition in epitaxial La0.67Ca0.33MnO3/NdGaO3(001) films

“…5,25,26 Moreover, the ex-situ annealing in oxygen atmosphere has been widely employed to optimize the crystallinity and eliminate oxygen deficiency for complex oxide films. 21,27,28 But it was also shown that the high temperature annealing may also facilitate the strain relaxation in large lattice-mismatched systems. 17,29 Therefore, the effect of ex-situ annealing on substrate coherency should be multiplicate, and surely needs to be further investigated.…”

Improved current transport properties of post annealed Y1Ba2Cu3O7−x thin films using Ag doping

“…This is clear from our results presented above and the results of several other groups. [1][2][3][4][5][6][7][27][28][29] McIntyre et al have reported on the J c dependence of film thickness for similar post annealed films. 27 They showed that there is a correlation between the density of 1-2-4 stacking faults and J c in that the 1-2-4 stacking faults act as planar core type flux pinning centers thereby increasing J c .…”

“…The BaF 2 coevaporation technique has proven superior in combination with optimized ex situ post annealing at low oxygen partial pressures. [1][2][3][4][5][6][7] In general, films processed under these conditions have a good surface morphology with no large surface outgrowths, high transition temperatures (T c ), high values of the critical current density (J c ) and good microwave properties. [3][4][5][6][7] These good properties can be obtained only if the YBCO thin films are grown on special substrates.…”