Synthesis, structural and electrical characterizations of Er_0.33Sr_1.67Ni_0.8Cu_0.2O_4−δ

Abstract

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.