Parameter boundaries for the heteroepitaxial growth of REBCO films by e-beam quantitative evaporation on inclined substrate deposited MgO buffered Hastelloy tapes

Abstract

The technology of electron beam (e-beam) quantitative evaporation of oxide powders at THEVA is quite unique among the many standard in-situ growth methods of high-temperature superconducting (HTS) films. As well known for YBa2Cu3O7-x (YBCO) film growth the temperature and oxygen pressure should be in proximity of the YBCO stability line in the Bormann diagram. In case of e-beam quantitative evaporation, we observe a shift in the DyBa2Cu3O7-x (DyBCO) stability line towards lower pressures and higher temperatures compared to YBCO. We investigated the temperature and oxygen partial pressure boundaries of epitaxial DyBCO growth on inclined substrate deposited MgO (ISD-MgO) buffered Hastelloy tapes. For completeness, the influence of powder stoichiometry and evaporation rate on HTS epitaxial growth is shown. For the first time high-quality HTS films have been grown by e-beam quantitative evaporation without employing an oxygen shuttle and with oxygen in the chamber background instead.

La1− x Mn1− y O3± δ buffer layers on inclined substrate deposited MgO templates for coated conductors

“…The LMO buffer layers were deposited on the MgO templates by evaporating an LMO granulate with a grain size of <0.5 mm by means of EB-PVD. The deposition system and the measurement of the substrate temperature (T sub ) are described in detail in [21].…”

“…A readily available DyBCO granulate, not optimized regarding the stoichiometry yielding the highest J c values, of Dy:Ba:Cu = 20:25:55 was used for this purpose. It is known that J c values of DyBCO films depend strongly on their composition [23] and can sharply decrease outside the optimal composition range [21,24,25]. Therefore, in the following discussion it has to be kept in mind that in the present work the DyBCO composition was not carefully optimized for yielding the highest J c .…”