High-temperature superconducting polymer-ceramic materials and their properties

Polymer-ceramic materials based on the oxide ceramic YBa2Cu3O7-x and a spectrum of different polymeric binders were obtained. The molding of polymer-ceramic compositions at 200 degreesC leads to the loss of superconducting properties (the Meissner effect is absent) regardless of the matrix type and to their recovery only after treatment of the materials in a dry oxygen stream at the alpha -transition temperature of a polymeric binder. Polyolefin binders elevate the onset temperature of superconducting transition for the compositions by 1-3 K as compared to the original ceramic, and the oxygen-containing polymers lower this parameter by 3-5 K. The molding of compositions at 130 degreesC results in materials with persistent superconducting properties. In this case, the polyolefin binders provide the same superconducting critical transition parameters of a composition as for the initial ceramic and acrylic and vinyl homo- and copolymers increase the superconducting critical transition temperature by similar to 1-2 K. The broadening of the superconducting transition temperature range of the compositions at their elevated shaping temperatures (greater than or equal to 160 degreesC) is due to the thermo-oxidative degradation of a polymeric binder. Factors that mitigate the effect of thermo-oxidative degradation of the matrix (reduction of pressing time, addition of antioxidants) allow the critical superconducting parameters of the compositions to be retained at the level characteristic of the original ceramic.