Syntheses and crystal structures of new ternary selenides: Rb3Yb7Se12 and CsEr3Se5

The ternary selenides Rb3Yb7Se12 and CsEr3Se5 have one-dimensional structures that are dependent on the sizes of the metal cations. The structure is composed of ReSe6 octahedral units that exhibit edge-sharing and the size of the channel cross sections range from five by four to six by four. The coordination numbers of the selenium of ternary selenides are five or six compared to three alkali metals and three rare-earth metal cations of ternary sulfides.