To clarify the relationship between Jc -H performance and microstructure, a determination of the flux pinning mechanism is necessary. However, multiple active pinning centers originating from different crystalline or chemical inhomogeneities may co-exist in most bulk high-Tc superconductors. This study presents a method to analyze the volume pinning forces of single-grained high-Tc superconductors with multiple additives (i.e. multiple pinning mechanisms) by means of the scaling theory of volume pinning force FP(H). The Jc -H curves as well as Fp/Fp,max vs. hp(1-h)q curves, where Fp,max is the maximum volume pinning force, h = H/Hirr, and the parameters p and q depend on the characteristics of flux pinning can be divided into two parts with different pinning mechanisms, i.e. J cδTc (Δk pinning) and Jcδl (normal pinning), respectively. By comparing the magnitude of the pinning force attributed to JCδTc and Jcδl, respectively, a semi-quantitative description of complex pinning behavior of single-grained superconductors with multiple pinning mechanisms can be obtained. It is found that the dominant pinning mechanism of RE-Ba-Cu-O materials (REBCO, RE: Sm and Nd) with nano-scale 211 additions is δTC pinning, while those with CeO2 and Pt/CeO2 additions is δl pinning. The relationship between these two pinning mechanisms with varying temperature and addition is also discussed.
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics
- Electrical and Electronic Engineering