EVIDENCE OF NEW LAYERED CUPRATES IN THE HG-A-GD-CU-O SYSTEM (A=BA, SR)

Syntheses, structures, electrical and magnetic properties of Hg(1-x)Gd (x)A(2)GdCu(2)O(7-delta) (A = Ba, Sr) and Hg2-xGdxBa2GdCu2O8-delta lay ered cuprates have been reported. These compounds crystallize in tetra gonal 1212- and 2212-type structures, respectively. They are prepared under normal oxygen pressure and are semiconductors. Magnetic suscepti bility measurements reveal antiferromagnetic ordering of Gd magnetic m oments in both 1212 and 2212 compounds in a narrow temperature range ( T-N = 2.25-2.4 K). Electron microscopy studies of the Hg-Ba-Gd-Cu-O sy stem prepared under an oxygen pressure of a few bars evidenced intergr owths between the 1212 and 123 structures.