Effect of Partial Lanthanide Substitutions of Gd123 Submicronic Powder

GdLnxBa2-xCu3Oy (Ln=La, 0 ≤ x ≤ 0.6;Ln=Nd, Sm,Eu, 0 ≤ x ≤ 0.5) (Gd123:Ln) samples were synthesized using the sol-gel method. The homogeneity region, variation of the crystal lattice and oxygen stoichiometry of the Gd123:Ln solid solutions were studied as a function of the substitution degree x. It was shown that the homogeneity region becomes wider when going from Eu
³⁺
(x ≤ 0.35) to La
³
+ (x ≤ 0.5), but for all lanthanides the symmetry changes from orthorhombic to tetragonal for x ~ 0.05. Measurements of the electrical resistance of Gd123:Ln samples in the temperature range 77-300 K revealed superconducting transition temperatures over 77 K only for x=0 and x=0.05.