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The U/n process has been used to introduce quasi-columnar pinning centers into Nd123, textured in 1% O 2 , 99% Ar. The process involves adding 235 U to precursor powders of the superconductor, texturing, and irradiating with thermal neutrons. The two resulting ions, from each nuclear fission, cause aligned discontinuous electronic damage of length ∼5.4 μm, which acts as a pinning center. Best results for J c require U deposits spaced by s ⩽5.4 μm. This has been achieved by deposits containing two foreign elements, U and Zr, and three native elements. The deposits of UZrNdBaO and Nd422 refined by the Zr, act as additional non-aligned pinning centers. The U/n process increases J c by a factor R J ⩾10, to values of J c ∼274 kA/cm 2 at T =77 K, B =666 G. |
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