The low-field signal (LFS) of microwave absorption and ESR spectra have been studied in multiphase BiSrCaCuO samples in which two superconducting phases with onset temperatures of 87 K and 112 K were found earlier by a.c. resistivity and d.c. magnetometry measurements. The temperature dependence of LFS intensity was found to be non-homogeneous with a characteristic step and peak-like features at 60 K, 87 K, 112 K and 116 K. These features are interpreted as evidence for the existence of two more superconducting phases: one with Tc = 116 K, that has not been previously observed in such samples, and other one with Tc = 60 K, that has already been identified in BiSrCaCuO samples prepared at lower temperatures. Comparison of the LFS behavior of BiSrCaCuO as a function of applied magnetic field and microwave power with that of YBa2Cu3O7 indicates a more strongly coupled intergrain morphology and more complicated topology of weak links in the Bi-based superconductor. LFS is shown to be a very sensitive method for the detection and characterization of small superconducting fractions in both non-superconducting and superconducting multiphase matrices.
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics
- Mechanics of Materials
- Mechanical Engineering
- Metals and Alloys
- Materials Chemistry