The crystal structure of Cu2Y2O5 was confirmed, using transmission electron microscopy, to be orthorhombic (Pna21, a = 1.08, b = 0.35, c = 1.23nm, V = 0.46nm3). Planar defects were observed to lie parallel to the a-b plane, with a displacement vector of ½[100], and arose from the movement of O atoms within the structure. These defects arose from disturbances of the Y-O bonding during formation of the crystal; that is, from a stacking fault. The density of the planar defects was further studied by varying the Ca dopant content from 0.05 to 0.4. It was found that there was no direct relationship between the planar defect density and the Ca concentration.

C.N.Feng, D.R.Lovett: Journal of Physics - Condensed Matter, 1998, 10[16], 3497-507