In situ observation and analysis of faceted crystal growth process in REBCO superconductive oxide

To clarify the nucleation and growth process of 123 crystals, growth of faceted RE123 (REBa2Cu3O7-x, RE = Nd, Sm, Gd, Y) crystals was observed in situ on MgO(1 00) by using high temperature optical microscope with zoom lens. RE123 crystals nucleated and grew at each undercooling (Delta T= 13-50 K). Growth rate (u) and incubation time (t(inc)) for nucleation were obtained from the relationship between the position of faceted interface and time (1). u increased with increasing Delta T-r(2), where Delta T-r = Delta T/T-p, T-p was peritectic temperature. Nucleation rate (I-v) was obtained from the relationship between the number of nucleated crystals (n) and time. I-v increased with increasing of exp(-B/Delta T-r(2)), where B was a constant. Both u and I-v under a fixed Delta T increased with increasing T-p: u(Nd123) > u(Sm 123) > u(Gd 123) and I-v(Nd123) > I-v(Sm123) > I-v(Gd123) for T-p(Nd123) > T-p(Sm123) > T-p(Gd123) in At-1%O-2 atmosphere. (C) 2007 Elsevier B.V. All rights reserved.