THE CHARACTERISTICS AND NATURE OF PLANAR DEFECTS IN Y2CU2O5 AND Y2-XCAXCU2O5 WITH X = 0.05, 0.1, 0.2 AND 0.4

Planar defects found in Y2Cu2O5 have been studied in detail. These pla nar defects are parallel to the a-b plane with the displacement vector R = 1/2[100]. They arise from the movement of oxygen atoms within the structure. The dependence of the density of planar defects within Y2C u2O5 has also been studied by varying the amount of the dopant Ca, i.e . Y2-xCaxCu2O5 with x = 0.05, 0.1, 0.2 and 0.4. There is no direct rel ationship between the density of the planar defects and the concentrat ion of Ca.