Greatly Improved Trapped Magnetic Fields of REBCO Melt-Grown Bulks Through Reductive High-Temperature Post-Annealing
Takanori Motoki, Masaya Miwa, Mirei Semba, Jun‐ichi Shimoyama
Abstract
We investigated the effects of high-temperature post-annealing on magnetic field-trapping properties of REBa <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> Cu <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> O <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><sub>y</sub></i> melt-grown bulks composed of a single <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">c</i> -growth domain prepared by the single-direction melt growth (SDMG) method. High-temperature post-annealing at 900 °C under moderately reductive atmosphere for readily oxygenated bulks greatly improved trapped fields with maintaining circular concentric distributions. Oxygen diffusion was found to be further accelerated after post-annealing as well. An enhancement ratio of the trapped field averaged over all bulks through this post-annealing was ∼40% in the present study. In particular, a DyBa <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> Cu <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> O <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><sub>y</sub></i> bulk with 24.3 mm in diameter and 10.8 mm in thickness recorded a high trapped field of 1.09 T at 77 K.