Enhanced Flux Pinning Properties of MOD-Processed $ \hbox{YBa}_{2}\hbox{Cu}_{3}\hbox{O}_{7 - \delta}$ Thin Films With $\hbox{BaZrO}_{3}$ Nanoparticles Using a Ba-Deficient Coating Solution

Abstract

We report the flux pinning properties of YBa <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 <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">7-δ</sub> (YBCO) thin films with BaZrO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> (BZO) nanoparticles, fabricated by a fluorine-reduced trifluoroacetate-metal-organic deposition process. For this study, the Ba-deficient coating solutions (Y : Ba : Cu = 1 : 1.5 : 3) with various BZO contents ranging from 0 to 15 mol% were prepared by mixing Ba-trifluoroacetate with fluorine-free Y, Cu, and Zr sources. Precursor films were deposited on SrTiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> (001) substrates by dip-coating, pyrolized in a humid oxygen atmosphere, and finally fired at a high temperature in a reduced oxygen atmosphere. Highly enhanced critical current densities (J <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">c</sub> ) in magnetic fields were achievable from all BZO-doped samples. The optimally processed YBCO film with 7.5 mol% BZO nanoparticles exhibited the J <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">c</sub> values of 0.39 and 0.5 MA/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> at 77 K in 1 T and at 65 K in 3 T for H//c, respectively. The BZO nanoparticles of 10-50 nm size trapped in the YBCO matrix are considered to be responsible for enhanced flux pinning in BZO-doped YBCO films.