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  Oji, U.K.; Fang, H.; Ludwig, W.; Lhuisser, P.; Samothrakitis, S.; Larsen, C.B.; Hilger, A.; Manke, I.; Tovar, M.; Cubitt, R.; Kardjilov, N.: Investigating the flux pinning dependence on grain orientation in YBa₂Cu₃O_7-δ using neutron tomography. Materials Characterization 214 (2024), p. 114082/1-6

10.1016/j.matchar.2024.114082
Open Access Version

Abstract:
In this study, we report the first case of non-destructive characterization of the dependence of the flux trapping mechanism on the grain properties of a bulk type II superconductor using a combination of polarized neutron tomography and diffraction contrast tomography. The high temperature superconductor, YBa2Cu3O7-delta, has been used in this study due to its viable commercial growth processes typically resulting in the production of polycrystalline specimens. The diffraction tomography revealed the pseudo-single crystal nature of the sample i.e. a polycrystalline sample with 47 composite grains having a maximum grain misorientation angle of 1.86°. Polarized neutron tomography was used for characterization of the flux trapped in the material after field cooling to 90.5 K in a field of 0.5 mT and switching off the field. A combination of the results from these two non-destructive characterization techniques indicate a correlation between the anisotropy of the trapped flux with the orientation of the grains in the material in addition to a preference for the flux trapping in the grain boundaries.