The growth process of RE123 (REBa 2Cu 3O 7-x, RE = Nd and Sm) crystals in the atmosphere of Ar-1%O 2 were observed insitu to investigate the nucleation and growth process of faceted RE123 crystals from the liquid +422(Nd 4Ba 2Cu 2O 10) or 211 (Sm 2BaCuO 5) on MgO(100) substrate through a peritectic reaction by using high temperature optical microscope with zoom lens. The nucleated faceted 123 crystals grew at a rate depended on the undercooling (Δ T). Growth rate (u) and incubation time (t inc) for nucleation were obtained from the changes in position of faceted interface during isothermal solidification. Growth rate u (m/s) was approximated by the following relation: u=A g (Δ T r 2/η (T) ), where η (T) was the viscosity, Δ T= T p - T, Δ T r=ΔT/ T p, T was temperature, T p was peritectic temperature, A g was a constant: A g = 0.60×10 6 for Nd and A g=1.8×10 -5 for Sm. Nucleation rate(I v) was obtained from the relationship between the number of nucleated crystals(n) and time(t). I v(m -3 s -1) was approximated by I v= A n(1/η(r)) exp (-B/ΔT r 2), where A n and 5 were constants: A n = 3.5×10 7, B= 1.5 ×10 -3 for Nd, and A n = 12.5×10 7, B=3.2×10 -3 for Sm.
|ジャーナル||Nippon Kinzoku Gakkaishi/Journal of the Japan Institute of Metals|
|出版物ステータス||出版済み - 7 1 2006|
All Science Journal Classification (ASJC) codes
- Condensed Matter Physics
- Mechanics of Materials
- Metals and Alloys
- Materials Chemistry