T. Nurgaliev et al., MAGNETIC CHARACTERISTICS OF K-DOPED, NA-DOPED AND RB-DOPED YBCO CERAMICS, Journal of magnetism and magnetic materials, 144, 1995, pp. 1305-1306
The magnetic behavior of Na-, K-, Rb-doped YBCO ceramic samples is inv
estigated at ac magnetic field at 77 K. For small Rb and Na concentrat
ions, an increase of the field-dependent component of the critical cur
rent is observed. High dopant concentrations lead to deterioration of
the critical parameters of the YBCO material. The results are interpre
ted as due to 'soiling' of the intergranular boundary by the dopant im
purities and Cu excess.