Limits...
Powder X-Ray Reference Patterns of Sr 2 RGaCu 2 O y (R = Pr, Nd, Sm, Eu, Gd, Dy, Ho, Er, Tm, and Y)

View Article: PubMed Central - PubMed

ABSTRACT

X-Ray Rietveld refinements were conducted on a series of eleven lanthanide phases, Sr2RGaCu2Oy (2112 phase, R = Pr, Nd, Sm, Eu, Gd, Dy, Ho, Y, Er, Tm, and Yb) that are structurally related to the high Tc superconductor Ba2YCu3O7 (213). In the 2112 structure, instead of square planar Cu-O chains, tetrahedral GaO4 chains were found to run in a zig-zag fashion along the diagonal of the basal 213 ab-direction. Reference powder patterns for these compounds were prepared by using the Rietveld decomposition technique. The unit cell volume of these compounds follows the expected trend of the lanthanide contraction. The lattice parameters range from a = 22.9694(3) Å, b = 5.5587(2) Å, and c = 5.44743(7) Å for R = Pr, to a = 22.8059(2) Å, b = 5.46031(5) Å, and c = 5.37773(5) Å for R = Yb. An electon diffraction study of the Sm- and Er-analogs showed characteristic diffuse streaks along the b-axis, suggesting some disorder within the GaO4 chains.

No MeSH data available.


Crystal Structure of Sr2RGaCu2Oy [5].
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4862828&req=5

f1-j64won: Crystal Structure of Sr2RGaCu2Oy [5].

Mentions: Sr2RGaCu2Oy (Ga-2112) crystallizes in a space group Ima2 [4] with structure related to that of Ba2YCu3O7. Ba2YCu3O7 crystallizes in a space group Pmmm with lattice parameters of a = 3.8198(1) Å, b = 3.8849(1) Å, and c = 11.6762(3) Å [1]. Substitution of one-third of Cu in Sr2RCu3O6+y by Ga results in the chemical formula of Sr2RGaCu2Oy. The relationship between the lattice parameters of Sr2RGaCu2Oy and those of Ba2YCu3O7 was found to be: a(2112) ≈ 22.8 Å ≈ 2 · c(213), b(2112) ≈5.5 Å≈√2 · b(213) and c(2112) ≈5.4 Å≈√2 · a(213). The structure of the 2112 phase (Fig. 1) has been discussed in detail by Vaughey et al. [4] and Roth et al. [5]. In both the 2112 and 213 structures [6], double-layers of corner-sharing CuO5 pyramids are separated by the lanthanide ions. In Sr2RGaCu2Oy, the connection between two double-layers of CuO5 along the a-axis is mediated by GaO4 tetrahedra. Tetrahedral GaO4 chains were found running along the c-axis (the diagonal of the basal plane of the Ba2YCu3O7 compound) in a zig-zag fashion, which is contrast to the square-planar copper chains typically observed in the 213 compounds. The 8-fold oxygen coordination of R is similar to that found in the 213-phase. Sr plays the role of Ba in 213 by filling the large voids located approximately at the same x-coordinates as the apical oxygens of the CuO5 units. As a result, Sr has a total of 9-fold coordination.


Powder X-Ray Reference Patterns of Sr 2 RGaCu 2 O y (R = Pr, Nd, Sm, Eu, Gd, Dy, Ho, Er, Tm, and Y)
Crystal Structure of Sr2RGaCu2Oy [5].
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4862828&req=5

f1-j64won: Crystal Structure of Sr2RGaCu2Oy [5].
Mentions: Sr2RGaCu2Oy (Ga-2112) crystallizes in a space group Ima2 [4] with structure related to that of Ba2YCu3O7. Ba2YCu3O7 crystallizes in a space group Pmmm with lattice parameters of a = 3.8198(1) Å, b = 3.8849(1) Å, and c = 11.6762(3) Å [1]. Substitution of one-third of Cu in Sr2RCu3O6+y by Ga results in the chemical formula of Sr2RGaCu2Oy. The relationship between the lattice parameters of Sr2RGaCu2Oy and those of Ba2YCu3O7 was found to be: a(2112) ≈ 22.8 Å ≈ 2 · c(213), b(2112) ≈5.5 Å≈√2 · b(213) and c(2112) ≈5.4 Å≈√2 · a(213). The structure of the 2112 phase (Fig. 1) has been discussed in detail by Vaughey et al. [4] and Roth et al. [5]. In both the 2112 and 213 structures [6], double-layers of corner-sharing CuO5 pyramids are separated by the lanthanide ions. In Sr2RGaCu2Oy, the connection between two double-layers of CuO5 along the a-axis is mediated by GaO4 tetrahedra. Tetrahedral GaO4 chains were found running along the c-axis (the diagonal of the basal plane of the Ba2YCu3O7 compound) in a zig-zag fashion, which is contrast to the square-planar copper chains typically observed in the 213 compounds. The 8-fold oxygen coordination of R is similar to that found in the 213-phase. Sr plays the role of Ba in 213 by filling the large voids located approximately at the same x-coordinates as the apical oxygens of the CuO5 units. As a result, Sr has a total of 9-fold coordination.

View Article: PubMed Central - PubMed

ABSTRACT

X-Ray Rietveld refinements were conducted on a series of eleven lanthanide phases, Sr2RGaCu2Oy (2112 phase, R = Pr, Nd, Sm, Eu, Gd, Dy, Ho, Y, Er, Tm, and Yb) that are structurally related to the high Tc superconductor Ba2YCu3O7 (213). In the 2112 structure, instead of square planar Cu-O chains, tetrahedral GaO4 chains were found to run in a zig-zag fashion along the diagonal of the basal 213 ab-direction. Reference powder patterns for these compounds were prepared by using the Rietveld decomposition technique. The unit cell volume of these compounds follows the expected trend of the lanthanide contraction. The lattice parameters range from a = 22.9694(3) Å, b = 5.5587(2) Å, and c = 5.44743(7) Å for R = Pr, to a = 22.8059(2) Å, b = 5.46031(5) Å, and c = 5.37773(5) Å for R = Yb. An electon diffraction study of the Sm- and Er-analogs showed characteristic diffuse streaks along the b-axis, suggesting some disorder within the GaO4 chains.

No MeSH data available.