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A new compound Er0.33Sr1.67Ni0.8Cu0.2O4−δ (ErSr5Ni2.4Cu0.6O11) was prepared using the conventional solid state method and annealed at 1423 K in 1 atm of oxygen gas flow. The oxygen non-stoichiometry (δ = 0.47) was determined by iodometric titration. Rietveld refinement using powder X-ray diffraction data confirms that the sample adopts the K2NiF4-type structure (space group I4/mmm (Z = 2), a = 3.760 56(4) and c = 12.3889(1) Ǻ). The final reliability factors were: Rwp = 10.75%, χ2 = 2.51, Rp = 14.80%, RB = 4.77% and RF = 2.73%. Four probe electrical resistivity measurements were performed vs. temperature in the range of 320–540 K. A semiconducting behaviour over the whole range of temperature, with a maximum conductivity of 0.026 S cm−1 is observed at 439 K.

The new title compound is synthesized by a sol-gel method from stoichiometric amounts of Nd2O3, SrCO3, NiO, and CuO dissolved in an aqueous nitric acid solution containing citric acid and ethylene glycol followed by calcination of the resulting product at 1173 K for 24 h in an alumina crucible, and annealing under flowing Ar at 1473 K for 8 d. The samples are characterized by powder XRD and resistivity measurements. DySr5Ni2.4Cu0.6O≈11.5 crystallizes in the tetragonal space group I4/mmm with Z = 2 (K2NiF4-type structure). It exhibits semiconducting behavior in the temperature range 294-579 K with a conductivity maximum of 0.4 S/cm at 510 K. -(HAMDI, S.; OUNI, S.; CHAKER, H.; ROHLICEK, J.; BEN HASSEN*, R.; J. Solid State Chem. 184 (2011) 11, 2897-2901, http://dx.