Macrosegregation of Y₂Ba₁Cu₁O₅ particles in Y₁Ba₂Cu₃O_7−δ crystals grown by an undercooling method

Macrosegregation of Y₂Ba₁Cu₁O₅ (Y211) particles was observed in Pt-added Y₁Ba₂Cu₃O_7−δ (Y123) crystals grown by an undercooling method. It was found that the macrosegregation of Y211 particles depended on the growth direction and the growth rate (R) as a function of undercooling (ΔT). The amount of Y211 particles in Y123 crystals grown at large R was larger than at small R. Also, the amount of Y211 in Y123 growing along the a-direction was larger than that along the c-direction. Further, it was noted that the smaller Y211 particles in size were distributed in Y123 grown at large R. These phenomena could be at least qualitatively explained by the prevalent trapping/pushing theory. In the direct observation of magnetic flux with the Faraday effect of iron garnet film, the flux pinning force was found to be in good agreement with the macrosegregation of Y211 particles.