Natural strategies for creating non-equilibrium morphology

Self-repairing, as a natural phenomenon, has been vastly observed and investigated in a variety of fields. With self-reparability, living species self-heal their wounds to restore physiological functions while non-biological materials return to their original states, e.g., thin surface layer growth occurs in the regeneration of incomplete KH2PO4 crystals. Here, we developed two seeding strategies for creating incomplete crystallographic shapes (i.e., right-angled concave corners) of YBa2Cu3O7−δ (YBCO) superconducting crystals with self-repairing capability in top-seeded melt-growth. One is in situ self-assembly seeding, by which self-reparability promotes YBCO growth, while the other is vertically-connected seeding, by which self-reparability triggers YBCO nucleation. Consequently, rapid crystallization originated at concave corners and swiftly generated initial growth morphology approaching equilibrium. Furthermore, these rapid-growth regions including the concave crystal or seed innately functioned as sizable effective seeding regions, enabling the enlargement of c-oriented growth sector and the enhancement of properties for YBCO crystals.