X-ray diffraction analysis of powder and thin film of (Gd _1-xy_x)₂O₃ prepared by sol-gel process

The mixed oxide (Gd_1-xY_x)₂O₃ (0.0 ≤ x ≤ 1.0) were synthesized, as powder and thin film, by a sol-gel process. X-ray diffraction data were collected and crystal structure and microstructure analysis were performed using Rietveld refinement method. All samples were found to have the same crystal system and formed solid solutions over the whole range of x. The cationic distribution, Gd³⁺ and Y ³⁺, over the two non-equivalent sites 8b and 24d of the space group Ia3 is found to be random for all values of (x). The lattice parameter is found to vary linearly with the composition (x). Replacing Gd³⁺ and Y ³⁺ by each other introduces a systemic decrease in the x-coordinate of cation position (24d) and slight changes in the oxygen coordinates. Crystallite size and microstrain analysis is performed along different crystallographic directions and anisotropic changes are found with the composition parameter (x). The average crystallite size ranges from 75 to 149 nm and the r.m.s strain from 0.027 to 0.068 × 10^-2. Textured Gd_1.841Y_0.159O₃ (400) buffer layers, with a high degree of alignment in both out-plane and in-plan, are successfully grown on cube textured Ni (001) tape substrates by sol-gel dip coating process. The resulting buffer layers are crack-free, pinhole-free, dense and smooth. YbBa₂Cu₃O_7-x (YbBCO) thin film could be (00l) epitaxially grown on the obtained buffer layer using sol-gel dipping technique.