Crystal-lattice modulation of the metal–insulator transition system PrRu4P12 studied by X-ray diffraction

Abstract PrRu4P12 exhibits a metal–insulator phase transition at T MI =60 K . In the insulating phase below TMI, X-ray superlattice reflections characterized by the wave vector q 0 =[1,0,0] were observed. The intensities at various reciprocal-lattice positions are reproduced by a model of modulated structure with the space group Pm 3 in which Ru and P displacements are about 0.074% and 0.06%, respectively of the lattice constant. Thus, the transition can be interpreted as the gap formation due to the nesting of Fermi surface with 2 k F =[1,0,0] .