Bi₂Sr₂CaCu₂O_x ceramic powder prepared by a solid state reaction was encupslated in SUS304 stainless steel mold with dimensions of 22^φ(O.D.) - 10^φ(l.D.) x 25mm. The mold was preheated at 840°C for 10 minutes and was hot-forged under uniaxial compressive load.
Many kinds of disordered nanostructure were observed in the hot-forged ceramics by TEM. They were many dislocation lines, micro-fracture and lattice undulation in crystal grains. The disordered structure changed, however, to a polycrystal composed of small recrystallized grains after annealing at 800°C for 1 hour.