The formation mechanism of fine Gd211 particles was studied by observing the size and morphology of Gd211 in the Gd-Ba-Cu-O melt-quenched from 1100 °C with various Gd211 particle sizes. The size and distribution of Gd211 particles at the partial melting stage depended on the size of initially added Gd211 particles. The precursor with fine Gd211 starting powder formed fine needle-shaped Gd211 particles after melting. The Gd211 refinement is ascribable to the increased number of Gd211 nucleation sites and growth inhibition by Pt addition. We also studied the refinement of RE211 (Nd422) particles in other RE-Ba-Cu-O (RE: Y, Dy, Eu, Sm, Nd) systems. In the cases of Y-, Dy- and Nd-systems, the size of RE211 (Nd422) particles could be reduced by decreasing the size of RE211 (Nd422) starting powders. In contrast, the employment of fine RE211 starting powder was not so effective for the size reduction of RE211 particles in the Eu- and Sm-systems.
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