Аннотация:Fe32+δGe35−xSix was synthesized using solid-state and chemical vapor transport reactions both in powder and single crystalline forms. Single crystal and high-resolution powder X-ray diffraction experiments revealed Fe32+δGe35−xSix to be a third member of the Fe32+δGe35−xEx (E = p-element) family of ternary compounds alongside Fe32+δGe33As2 and Fe32+δGe35−xPx. Fe32+δGe35−xSix features a two-dimensional intergrowth structure of two parent structure types: MgFe6Ge6 and Co2Al5. Similarly to the other members, the stabilisation of the intergrowth structure in Fe32+δGe35−xSix occurs as a result of the p-element substitution in the MgFe6Ge6-type block. The intergrowth breaks the kagome net of MgFe6Ge6 into individual hexagrams, while providing additional layers of geometrically frustrated atomic arrangements. Magnetic measurements showed antiferromagnetic ordering at TN ~ 150–160 K and spin reorientation below 80–90 K owing to the competition between magnetic interactions in the frustrated magnetic lattice of Fe32+δGe35−xSix.
