Construction of copper halide networks within layered perovskites.Syntheses ad characterization of new low-temperature copper oxyhalides

摘要

The constructution of two-dimensional(2D) copper halide networks within a variety fo perovskite hosts by a lowtemperature topochemical method is demonstrated.Ion exchange between some layered perovskite oxides of the type A'[A_(n-1)(M,M')_nO_(3N+1)](A'=alkali metal,H,NH_4,A=alkaline earth,rare earth,or Bi;M,M'=Nb,Ta,Ti;n=2,3) with CuX_2 (X=Cl,Br) results in the oxyhalides (CuX)[A-(n-1)(M,N')_nO_(3n+1)].Rietvel refinements from X-ray powder diffraction data show that the structures of these new copper oxyhalides containege-sharing CuO_X_4 octahedra sandwiched between the M/M'O_6 octahedra of the perovskite slabs.Teh compounds are low-temperature phases that decompose well below 700degC.The copper oxyhalides exhibit antiferromagnetic ordering resultin gfrom the magnetic exchange interactions within in planar Cu-X networks.