Effects of high-energy, heavy ion irradiation on the properties of Y-Ba-Cu-O high-Tc superconductors are examined. The irradiating medium consists of accelerated Bi-ions, having atomic weight of 114.82. The detected hysteresis loops have very different forms and sizes in unirradiated and in irradiated states, referring to the strong effect of the irradiation. Striking variations of critical current- and magnetic parameters up to the extent of 30-40% in this series of specimens were detected. Their direct reason can be looked for in the change of the atomicmolecular microstructure of the specimens, as an effect due to the irradiation. This is decided by both of the energy and density of the ions arriving onto the surface of the samples [1,2]. It means that the effect produced by the irradiating individual ions depends also on the exact local place of the specimens, on nanometer scale, determined by their given molecular structure, bonding relationships and microstructural stability. In this way, the irradiation experiments can provide some new information on the atomic-molecular properties of the specimens in question. As a genuine smart material, the Y1Ba2Cu3O7-d high-Tc superconductor is able to reply to any external influence, changing its own qualities according to that effect.