Evidence for a Peierls transition in the blue bronzes K0.30MoO 3 and Rb0.30MoO3

Abstract

X-ray diffuse scattering studies of the quasi one-dimensional blue bronzes K0.30MoO3 and Rb0.30MoO3 show that the metal insulator phase transition observed at Tc = 180 K is accompanied by a periodic lattice distortion. Analysis of the diffuse scattering observed well above Tc shows that the lattice instability involves mainly MoO6 octahedra. The anisotropy of the electrical resistivity is consistent with a quasi one-dimensional conduction band built on hybridized molybdenum 4d and oxygen p π orbitals. Together with the electrical properties, the structural results corroborate that the phase transition of the blue bronzes can be viewed as a Peierls distortion.