Anisotropic growth morphology and platelet formation in large grain Y–Ba–Cu–O grown by seeded peritectic solidification

Abstract

The characteristic platelet-like structure of large grain superconducting Y-Ba-Cu-O fabricated using peritectic solidification techniques has been documented widely as a key microstructural feature of this material. The platelet formation mechanism is investigated via a detailed comparison of the difference in morphology of YBa 2 Cu 3 O 72d (123) growth fronts propagating along different lattice directions. The development of YBa 2 Cu 3 O 72d dendrites between the growth front and local Y 2 BaCuO 5 (211) particles is observed to be a key feature of the growth mechanism along all directions. Dendrites broaden rapidly for growth fronts propagating along the c-axis due to the enhanced growth rate of Y-Ba-Cu-O in the a-b plane to yield a uniform, regular growth morphology. Dendrite broadening is inhibited for grain growth along the a-b directions, however, due to the slower growth rate along the c-axis, which yields an irregular extended growth front. Growth along the a͞b direction commonly results in the formation of regions consisting of 123 dendrites which may connect 211 particles. Continued solidification of the 123 phase in such regions results in the development of platelet structures perpendicular to the crystallographic c-axis in the YBa 2 Cu 3 O 72d phase matrix which may impede the flow of current through the grain in the superconducting state.

Single-grain growth, microstructure and superconducting properties of (Sm, Eu)123 superconductors with BaCuO2 xaddition

“…Furthermore, Schätzle et al [9] investigated the effect of BaCuO 2−x addition on the superconducting properties of melt-processed NdBa 2 Cu 3 O 7−δ . Unfortunately, their samples are polycrystalline or multi-domains, in which BaCuO 2−x precipitated at grain boundaries [10,11]. The role of BaCuO 2−x on the superconducting properties of single-domain samples has not yet been experimentally established.…”

Properties and Types of Superconductors

“…According to the periodic bond chain (PBC) principle grain growth rate along c-axis direction is 5.4 -7.3 times slower than the abplane [94]. Lo et al observed that Rc was considerably slower than the Ra by using the morphology of particles in YBCO growth front [95]. The groups of GdBCO samples were grown for 20 hours at various temperatures and were found that growth was lower along the c-axis as compare to the growth rate along ab-plane [96].…”

Local Dendrite Development during Seeded Peritectic Solidification of Large YBa2Cu3O7−δ Grains

“…The associated variation of yttrium concentration along the direction perpendicular to the front. Pockets of liquid may then form as the dendrites develop further, 21,22,33 123 growth front propagates at a steady macroscopic growth planar 123 growth fronts. Dendrite formation and development are driven by a local inhomogeneous concentration of yttrium rate, R:…”

“…[18][19][20] Furthermore, platelet formation vertical (parallel to c) and horizontal (parallel to a/b) directions has been related to the growth mechanism of melt-processed was examined using scanning electron microscopy (SEM). The YBCO, 21,22 which highlights the importance of detailed studcomposition of secondary phases in the vicinity of the growth ies of the morphology of the 123 phase during peritectic front was investigated using energy dispersive X-ray analysis solidification.…”

“…The associated variation of yttrium concentration along the direction perpendicular to the front. Pockets of liquid may then form as the dendrites develop further, 21,22,33 which are consumed slowly as the 123 phase 123 growth front (i.e., the z direction) is illustrated in the bottom section of this figure. The Y concentration is fixed as C 123,s solidifies.…”