Evidence of new layered cuprates in the Hg–A–Gd–Cu–O system (A = Ba, Sr)

Abstract

Syntheses, structures, electrical and magnetic properties Hg1 –xGdxA2GdCu2O7 –δ(A = Ba, Sr) and Hg2 –xGdxBa2GdCu2O8 –δ layered cuprates have been reported. These compounds crystallize in tetragonal 1212- and 2212-type structures, respectively. They are prepared under normal oxygen pressure and are semiconductors. Magnetic susceptibility measurements reveal antiferromagnetic ordering of Gd magnetic moments in both 1212 and 2212 compounds in a narrow temperature range (Tn= 2.25–2.4 K). Electron microscopy studies of the Hg–Ba–Gd–Cu–O system prepared under an oxygen pressure of a few bars evidenced intergrowths between the 1212 and 123 structures.