Powder X-ray reference patterns of Sr2RGaCu2Oy (R = Pr, Nd, Sm, Eu, Gd, Dy, Ho, Er, Tm, and Y)

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 T-c superconductor Ba2YC u3O7 (213). In the 2112 structure, instead of square planar Cu-O chains, te trahedral GaO4 chains were found to run in a zig-zag fashion along the diag onal of the basal 213 ab-direction. Reference powder patterns for these com pounds were prepared by using the Rietveld decomposition technique. The uni t cell volume of these compounds follows the expected trend of the lanthani de contraction. The lattice parameters range from a = 22.9694(3) Angstrom, b = 5.5587(2) Angstrom. and c = 5.44743(7) Angstrom for R = Pr, to a = 22.8 059(2) Angstrom, b = 5.46031(5) Angstrom, and c = 5.37773(5) Angstrom for R = Yb. An electon diffraction study of the Sm- and Er-analogs showed charac teristic diffuse streaks along the b-axis, suggesting some disorder within the GaO4 chains.