New York: Kluwer Academic Publishers-Plenum Publishers
An oxygen concentration dependent metal–nonmetal (MN) transition was observed for Rb0.23WO y with 2.80 < y < 3.08. As 2.80 < y < 3.0, the room temperature resistivity (ρRT) of the Rb0.23WO y is about 5 × 10−4Ω cm. While in the case of y > 3.04, the ρRT of the Rb0.23WO y exhibits a four orders of magnitude increase with a value of 5 Ω cm. Correspondingly, the lattice constant along c-direction slightly shortens as oxygen concentration increases from 2.80 to 3.08. The observed results suggest that the hybridization between W 5d (t2g) and O 2p orbitals might be responsible for the MN transition. In addition, similar measurements were performed for Rb x WO3.04 and Rb x WO2.85 with 0.19 < x < 0.27. No rubidium concentration dependent MN transition was observed, indicating the electronic structure of the host WO y is not modified significantly by varying the soluble rubidium concentration.