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

The construction of two-dimensional (2D) copper halide networks within a variety of perovskite hosts by a low-temperature topochemical method is demonstrated. Ion exchange between some layered perovskite oxides of the type A'[A(n-1)(M,M')(n)O3n+1] (A' = alkali metal, H, NH4; A = alkaline earth, rare earth, or Bi; M,M' = Nb, Ta, Ti; n = 2, 3) with CuX2 (X = Cl, Br) results in the oxyhalides (CuX)[A(n-1)(M,M')(n)O3n+1]. Rietveld refinements from W-ray powder diffraction data show that the structures of these new copper oxyhalides contain edge-sharing CuO2X4 octahedra sandwiched between the M/M'O-6 octahedra of the perovskite slabs. The compounds are Low-temperature phases that decompose well below 700 degreesC. The copper oxyhalides exhibit antiferromagnetic ordering resulting from the magnetic exchange interactions within the planar Cu-X networks.