Optimization of the Crystallization Process of TFA-MOD ErBCO Films on IBAD-Substrate Under Low-Pressure Conditions via DSD Approach

Abstract

Crystallization in a sub-atmospheric reactor could achieve higher production rate while dramatically reducing the flow rate of high-purity carrier gas. Due to enhanced supersaturation conditions at low total pressure, it is necessary to find the optimum processing window to avoid misoriented growth. This is extensive and incomplete when using one-factor-at-a-time experiments as significant parameters are often correlated. <p xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">We prepared ErBa₂Cu₃O_7-<i>_δ</i> (ErBCO) films by the TFA-MOD route with low-fluorine solutions on technical IBAD template with CeO₂ top buffer layer in an industrial reel-to-reel furnace. We used a novel design-of-experiment (DOE) technique, the Definitive Screening Design (DSD), to identify significant factors for improving critical temperature and microstructure of the films. Within the investigated range, lower crystallization temperature as well as lower total pressure are beneficial. With the new process window, the self‑field critical current density at 77 K was successfully increased from almost zero to 1 MA/cm². This shows that DSD is an attractive approach to optimize the CSD process under low-pressure conditions to enhance the growth rate or possibly achieve a reduction of carrier gas flow rate by a factor <i>p</i>_tot/<i>p</i>_atm of 3.3 for equal output as the atmospheric reactor. Further improvement of <i>J</i>_c is necessary and possible.