Neutron diffraction studies on La2−x Dy x Ca2xBa2Cu4+2x Oz superconductors

Abstract

Structural studies on Dy-substituted La-2125 type superconductors have been carried out by neutron diffraction experiments at room temperature using a monochromatic neutron beam of wavelength (λ) = 1.249Å. A series of samples with La 2-x Dy x Ca 2x Ba 2 Cu 4+2x O z stoichiometric composition, for x = 0.1 -0.5, have been studied for their structural properties. A tetragonal Y-123 unit cell was taken as the starting model for the Rietveld analysis. All the samples fit into the starting model, exhibiting no structural transition taking place with increasing dopant concentration. The results of Rietveld analysis and structural properties will be discussed in detail.

Neutron structural studies on the superconducting (Nd1−xCax)(Ba1.6La0.4)Cu3Oz system

“…The intermixing behavior of La and Ca occupancy variation with R ͑R = Nd, Dy, and Y͒ through neutron diffraction has also been observed in La-1113, La-2125, and R-123 systems. [16][17][18][19] It is well known that Ca substitution at the R-site decreases the oxygen content of R-123 compounds; however, La substitution at the Ba-site increases the oxygen content. 12,13 Analysis of the neutron diffraction data reveals that some Ca atoms occupy the actual Nd-site while some occupy the Ba site.…”

Structural and magnetic studies on La2 xDyxCa2xBa2Cu4+2xOztype superconducting oxides

“…The structural analysis reveals tetragonal La-123 type structure with the P4/mmm space group for all samples studied in the x = 0.1-0.5 range. Detailed analysis of neutron diffraction data on La 2−x Dy x Ca 2x Ba 2 Cu 4+2x O z (with x = 0.1-0.5) by the Rietveld refinement method has been reported in [18]. A typical unit cell of the La-2125 compound is shown in figure 1.…”

Low Temperature Bond Valence Sum Study of La_1.7 Dy_0.3 Ca_0.6 Ba₂ Cu_4.6 Oz Oxide Superconductors

“…La 2-x RE x Ca 2x Ba 2 Cu 4+2x O z (RE = rare earth) superconductors are built by introducing CuO and CaO in equal proportions along with RE ions in a non-superconducting La 2 Ba 2 Cu 4 O z [1][2][3][4]. These compounds, generally referred to as La-2125 compounds, crystallize in La-123 type tetragonal structure with space group P4/mmm.…”

“…These compounds, generally referred to as La-2125 compounds, crystallize in La-123 type tetragonal structure with space group P4/mmm. Among the rare-earth substituted La-2125 compounds, La 2-x Dy x Ca 2x Ba 2 Cu 4+2x O z (0.0 ≤ x ≤ 0.5) have been previously studied by room temperature neutron diffraction (RT-ND) measurements [3,4]. The Dy substituted La-2125 compounds show increase in superconducting transition temperature with increasing dopant concentration, with maximum T c of 75 K for x = 0.5 compound.…”