A semi-quantitative method to analyze the complex pinning mechanisms in single-grained high-T/sub c/ superconductors

To clarify the relationship between J/sub c/-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-T/sub c/ superconductors. This study presents a method to analyze the volume pinning forces of single-grained high-T/sub c/ superconductors with multiple additives (i.e. multiple pinning mechanisms) by means of the scaling theory of volume pinning force F/sub p/(H). The J/sub c/-H curves as well as F/sub p//F/sub p,max/ vs. h/sup p/(1-h)/sup q/ curves, where F/sub p,max/ is the maximum volume pinning force, h=H/H/sub irr/, 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/sub c/spl delta/Tc/ (/spl Delta//spl kappa/ pinning) and J/sub c/spl delta/l/ (normal pinning), respectively. By comparing the magnitude of the pinning force attributed to J/sub c/spl delta/Tc/ and J/sub c/spl delta/l/, 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 /spl delta/T/sub c/ pinning, while those with CeO/sub 2/ and Pt/CeO/sub 2/ additions is /spl delta/l pinning. The relationship between these two pinning mechanisms with varying temperature and addition is also discussed.