PREPARATION AND CHARACTERIZATION OF A SODIUM INSERTION COMPOUND OF HYDROGEN MOLYBDENUM BRONZE, NA0.25(H2O)Y[H0.21MOO3]

A new red hydrogen-sodium co-insertion compound of molybdenum trioxide, Na0.25(H2O)y[H0.21MoO3], has been prepared which possesses sodium ions in its interlayer space and protons in the intralayer positions. Two phases of this compound were observed depending on hydration water content. According to XRD investigations, there was little difference in crystal structure between this compound and hydrated sodium molybdenum bronze. The Na-H co-insertion molybdenum bronze was characterized by XRD, NMR and thermogravimetric and differential thermal analysis (TG-DTA) and showed an interesting structural transformation at ca. 550 K which was related to the change in interlayer spacing. It is suggested that the transformation results from structural defects generated by dehydration due to intralayer protons.