BI-BASED SUPERCONDUCTING OXIDE MAGNETIC SHIELD MATERIAL

PURPOSE:To obtain a Bi-based oxide magnetic shield material whose attenuation factor is superior to that in conventional cases by a method wherein the C face of Bi oxide crystal grains at least on a surface layer is oriented in parallel with the surface of the Bi oxide magnetic shield material. CONSTITUTION:A Bi oxide magnetic shield material which is provided with a surface orientation property, whose attenuation factor is excellent and which contains Pb is obtained by a method in which, it is sintered in an oxygen atmosphere, and then it is pressed by a hot hydrostatic pressure. When HIP is controlled, also the thickness of a surface orientation layer can be controlled. In addition, the density of the Bi oxide magnetic shielding material can be enhanced and also its mechanical strength can be improved. A texture in which the longitudinal direction of scale-shaped particles 6 of a Bi oxide containing Pb is oriented densely in parallel with the surface can be observed; the C face of the scale-shaped particles 6 of the Bi oxide is in parallel with the length direction of the scale-shaped particles. As a result, a layer in which the C face of the Bi oxide containing Pb is oriented on the surface is formed on the surface of a crucible-shaped magnetic shield material; the measurement result by which the attenuation factor of a magnetic field is excellent can be obtained.