A facile synthesis of pseudo one-monodimensional ternary molybdenum chalcogenides M2Mo6X6 (X = Se,Te; M = Li,Na..Cs)

Compounds of this family are of great interest because of their pseudo one-dimensional structure of linear chains of (Mo₃)¹_∞ clusters. High temperature solid state reactions (1100°C) are generally used to prepare members of this class, such as In₂Mo₆Se₆. This paper describes ion exchange reactions of In₂Mo₆X₆ with alkali iodide and chloride salts at 550°C to give M₂Mo₆X₆ and mixed solid solutions In_2?xM_xMo₆X₆ (M=Li, Na, K, Rb, Cs; X=Se, Te). Furthermore, we show that ion exchange provides a low temperature route to prepare phases which are not stable at high temperature, such as In_2?xM_xMo₆Se₆ 0 ≤ x ≤ 2 and M = alkali. When M = Li, the lithium can be partially removed by oxidation with iodine producing non stoichiometric ternary molybdenum chalcogenides In_2?xMo₆Se₆ (0 ≤ x ≤ 1.8). Superconducting measurements indicate that only Tl₂Mo₆Se₆ is superconducting above 1K.