INFLUENCE OF CO-DOPING ON STRUCTURE AND CRITICAL-TEMPERATURE OF Y(NI1-XCOX)(2)B2C AND LU(NI1-XCOX)(2)B2C

The suppression of superconductivity and the structural properties of doping with Co for Ni in the new borocarbide superconductors of the st oichiometry RE(Ni1-xCox)(2)B2C for the nonmagnetic rare earth elements RE = Y and Lu have been studied. The superconducting phase interval f or increasing Co concentration x is larger for RE = Lu than for Y. Whi le the lattice parameter c decreases for increasing Co concentration f or both rare earth elements, the lattice parameter a shows a different behaviour for Y and Lu. A decrease in crystallinity of the samples is observed in the X-ray diffraction patterns for increasing Co concentr ation.