Microstructure of YBCO/Semicrystalline Polymer Composites and its Effect on Percolation

Ceramic-polymer composites using conducting YBa2Cu3O7-x (YBCO) powder have been fabricated. Atomic force microscopy (AFM) and Scanning electron microscopy (SEM) images are used to provide new information about the more influent microstructural features. The effect of microstructure on percolation is studied for all the composites. Results indicate that percolation and subsequent positive temperature coefficient (PTC) behavior are related to the powder characteristics, composite microstructure, and ceramic-polymer interface. The reproducibility of the resistivity-temperature behavior for the polyethylene composites upon thermal cycling is illustrated and found that the room temperature resistivity increases by about 1 order of magnitude from the first to the forth cycle.