ALKALI-METAL MANGANESE SELENIDES AND TELL URIDES - SYNTHESIS, CRYSTALAND SPIN STRUCTURES

The compounds Rb2Mn3Se4, Cs2Mn3Se4, Rb2Mn3Te4 and Cs2Mn3Te4 were synth esized by the reaction of alkali metal carbonates with chalcogen and M n or MnCO3 in a stream of hydrogen charged with chalcogen. Structural investigations show that all compounds crystallize in isotypic atomic arrangements (Cs2Mn3S4-type, space group Ibam, Z = 4). Additionally ne utron diffraction experiments were carried out and yielded the spin st ructures of Rb2Mn3Se4 and Cs2Mn3Se4 (Shubnikov space group Ibam'). The structural related selenides ALiMnSe(2) and ALiZnSe(2) (A = K, Rb or Cs) were synthesized by analogous reactions. All these compounds are i sotypic and crystallize in the BaZn2P2-structure type.