Interaction of superconducting Y1Ba2Cu3O7-x targets with 1.064 μm Q-switched Nd:yttrium-aluminum-garnet laser

Bulk superconducting targets of Y1Ba2Cu3O7-x were prepared and characterized for resistance, structure, morphology, and composition. The targets were irradiated by a Q-switched 1.064 mu m wavelength Nd:yttrium-aluminum-garnet (YAG) laser having 20 ns pulse duration at 2.0 J/cm(2) (shot) energy density. A cumulative laser exposure of the target surface results in the formation of microscopic conical columnar structures aligned parallel to the incident laser beam. Evolution of these structures in the present case is attributed to the longer penetration depth of optical radiation and localized material removal by microexplosions beneath the surface. Energy dispersive analysis by an x ray of the individual column shows microscopic phase segregation and erosion accompanied by shadowing as the primary cause of the cone formation process. (C) 1998 Laser Institute of America. [S1042-346X(98)00201-0].