Solidification processes, which are used to produce rare-earth (RE)-Ba-Cu-O high critical temperature, Tc superconductors, are effective to obtain a high critical current density, Jc at 77 K, and are very promising for high field applications as a superconducting quasi-permanent bulk magnet, flywheels, magnetic shielding, current leads and levitation systems with liquid nitrogen refrigeration. Isothermal undercooling solidification in air with oxygen annealing and Nd123/MgO thin film cold seeding technique were applied to textured Ag-doped Y-Ba-Cu-O superconducting bulks to seek high-efficiency of process, homogeneity of composition and feasibility of batch production. A large single domain, 38 mm × 38 mm in size, was exemplified. The result implies that the melt-process to which the isothermal method and thin film seeding are applied in the Y system fits the production of larger bulks for large-scale applications.