Effect of Pressure on Electrical Resistivity and Crystal Structure of Quasi‐Two‐Dimensional Mo₄O₁₁

Abstract

Abstract Electrical resistivities ϱ and lattice parameters of quasi‐two‐dimensional crystals of monoclinic η‐Mo 4 O 11 and orthorhombic γ‐Mo 4 O 11 are measured under hydrostatic pressure up to 1.2 GPa at room temperature. Both crystals have negative pressure coefficients of ϱ, which can be qualitatively explained by a phonon stiffening effect. In particular, the pressure dependence of ϱ for γ‐Mo 4 O 11 shows a drastic drop or jump at P c = 0.3 GPa, whose magnitude and the pressure coefficients are strongly dependent on the sample resistivity or degree of stoichiometry. It is suggested that the change of a small amount of MoO 4 tetrahedra into MoO 6 octahedra induced by excess oxygen atoms is responsible for such structure‐sensitive properties.