Structural Phase Transformation in REX (La, Ce and Pr) Chalcogenides: A Combined Study

The chalcogenides of the rare earth have always been considered for the study because of their partially filled f-electrons. These partially f-electrons are accountable for various unusual physical and chemical properties of the materials. Some thermodynamic variables also play important role for various other properties like valence change, structural change and state change. The pressure is one of the thermodynamic variables under which solids change their structures. Generally, binary rare earth chalcogenides have NaCl-type structure under ambient conditions. In this paper we have discussed pressure induced structural phase transition in chalcogenides (X=S, Se and Te) of rare earth elements (RE = La, Ce and Pr) as LaX, CeX and PrX compounds along with their ground state properties using various first principles theories and experimental techniques. These compounds undergo pressure driven structural phase transition from NaCl-type (B1) to CsCl-type (B2).