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008ChemInform Abstract It is found that the degree of substitution of Co or Ni for iron in the title system strongly influences the electrical properties. The electrical resistivity markedly decreases with increasing x. The structure within the title system follows the general building principles of the series (AO)2M2Bn-1FenO3n+1+z and consists of perovskite-like slabs with one iron-oxygen octahedron intercalated between AO double layers.

In the system Pr2‐xCuxRu2O7‐z homogeneous cubic pyrochlores are formed in the range 0 ≤ x ≤ 0.375.

Samples of the new family of iron compounds of the general formula of title are prepared by heating appropriate mixtures of Bi(NO3)3·5 H2O, PbO, Sr(NO3)2, and Fe powder in corundum boats in air at temp. of 860‐880 °C (n = 1) or 930‐950 °C (n = 2) for several days.

is prepared with various Bi:Pb ratios by heating mixtures of Bi(NO3)3·5 H2O or Bi2O3, PbO, Sr(NO3)2, and Fe powder in corundum boats at 800‐830 °C for several days.