Effect Of Partial Lanthanide Substitutions Of Gd123 Submicronic Powder

GdLn(x)Ba(2-x)Cu(3)O(y) (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 Eu3+ (x <= 0.35) to La3+ (x <= 0.5), but for all lanthanides the symmetry changes from orthorhombic to tetragonal for x similar to 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.