Alterations in Crystalline Parameters of Y 1-x Sm x BaSrCu ₃ O 6+ z Compound Induced by Heat Treatment

This study investigates the influence of heat treatments on the structural and superconducting properties of Y 1− x Sm x BaSrCu 3 O 6+ z compounds ( x = 0, 0.4, and 1.0). The samples were prepared using conventional solid‐state synthesis and subjected to two annealing protocols: direct oxygen (O 2 ) annealing and an argon preanneal followed by oxygen (Ar + O 2 , “AO”). X‐ray diffraction (XRD) with Rietveld analysis was employed to determine the crystalline parameters and the orthorhombicity of the samples. The argon–oxygen (AO) treatment generally increased the b lattice parameter and decreased a , except for YBaSrCu 3 O 6+ z ( x = 0), where both parameters increased. Across the composition range, the orthorhombic structure remained stable, except for SmBaSrCu 3 O 6+ z ( x = 1) under O 2 annealing, which exhibited a pseudotetragonal structure. Superconducting critical temperature (Tc) increased after AO annealing in all cases except for YBaSrCu 3 O 6+ z , where it decreased from 83 to 81.7 K. These results highlight the role of crystalline parameters and oxygen ordering/disordering in the Cu(1)O plane in controlling Tc and the hole density (p) in the Cu(2)O 2 planes. The study provides new insights into the interplay between Sm substitution, annealing atmosphere, and superconducting properties.