Superconducting Tm123 granules on non-superconducting Pr123 seeds

Annealing of a two-component mixture of metal oxide powders with the same crystal structure, but different peritectic temperatures, can lead to accelerated growth of granules of the low-melting phase. This paper describes the preparation and investigation of the microstructural and magnetic characteristics of large grain ceramics in which PrBa$_2$Cu$_3$O$_{7-\delta}$ (Pr123) is a refractory component, and TmBa$_2$Cu$_3$O$_{7-\delta}$ (Tm123) is a component with a lower peritectic temperature. In a compound prepared from 80 vol.% Tm123 and 20 vol.% Pr123, the size of superconducting Tm123 granules reaches 0.1 mm. The presence of large granules leads to high values of remanence magnetization and trapped magnetic flux. Despite the presence of 20% of the non-superconducting phase, the remanence magnetization in the resulting compound is only 1.07 times less than in the related large grain ceramics of 80 vol.% Tm123 and 20 vol.% Nd123, and exceeds the values of the remanence magnetization in polycrystalline superconductors obtained by standard solid-phase synthesis.