Top-Seeded Melt-Growth of YBa₂Cu₃O_x Crystals for Neutron Diffraction Studies
D.C. Peets, Ruixing Liang, C. Stock, W.J.L. Buyers, Z. Tun, L. Taillefer, R.J. Birgeneau, D.A. Bonn, and W.N. Hardy
Published in Journal of Superconductivity 15, 531-4 (2002).
Preprint: cond-mat/0209418.

We have grown cubic centimetre-size crystals of YBa₂Cu₃O_x suitable for neutron studies, by a top-seeded melt-growth technique. Growth conditions were optimized with an eye toward maximizing phase purity. It was found that the addition of 2% Y₂BaCuO₅ and 0.5% Pt (by mass) were required to prevent melt loss and to obtain the highest crystallinity. A neutron diffraction study on a mosaic of six such crystals found that the final Y₂BaCuO₅ concentration was 5%, while other impurity phases comprised less than 1% by volume. The oxygen content was set to x=6.5, the crystals were detwinned and then carefully annealed to give the well-ordered ortho-II phase. The neutron study determined that 70% of the mosaic's volume was in the majority orthorhombic domain. The neutron (0 0 6) and (1 1 0) rocking curve widths were ~1° per crystal and ~2.2° for the mosaic, and the oxygen chain correlation lengths were >100 Å in the a- and b-directions and ~50 Å in the c-direction.