Abstract
The elementary pinning force of grain boundaries was estimated for superconducting V3Ga tapes prepared by the surface diffusion method on pure and zirconium-doped vanadium tapes. It is 1.6-3.7×10-4 N/m for pure vanadium tapes and 3.8-6.2×10-4 N/m for zirconium-doped tapes. These values are much larger than the theoretical values by Zerweck, by Yetter et al. and by Welch based on the electron-scattering mechanism. Although Thuneberg's theory givesa value comparable to the observed results, it is incompatible with the observed increase in the elementary pinning force with the addition of zirconium.