Phase Transitions at High Temperature in Intercalation Compounds Mn_1/4NbS₂ and Mn_1/4TaS₂

Abstract

Phase transitions in intercalation compounds Mn_xNbS₂ and Mn_xTaS₂ (x=1/4 and 1/3) have been investigated at high-temperature region using a magnetic balance and an X-ray diffractometer. In Mn_1/4NbS₂, the discontinuous changes of the magnetic susceptibility and the lattice parameter c are observed at 640 K. In Mn_1/4TaS₂, similar discontinuities are observed at 670 K. From the temperature dependence of the superlattice reflections, it has been found that these discontinuities are manifestation of the structural phase transition associated with the order-disorder of the intercalated Mn atoms and the displacement of the Nb, Ta and S atoms.