Structural and electrical conductivity studies on rutile solid solutions [FexTi1-2xMxO2 (M = Nb, Ta)]

In this study, FexTi1-xMxO2 (M = Nb, Ta; 0 less than or equal to x less tha n or equal to 0.5) solid solutions have been synthesized from both ceramic and gel methods, and electrical and structural characterization has been ca rried out. The solid solutions show rutile structure except for the case of FeNbO4, which forms an orthorhombic structure. The electrical behaviour of the system studied corresponds to extrinsic p-type semiconduction and it i s related to the presence of Fe(II) ions. Conductivity is enhanced by local distortions of the MO lengths associated with ordering oxidation states su ch as those in Fe3O4. The distortions are more frequent when the asymmetry is greater (M = Nb). No electrical changes have been detected when the synt hesis method is different. (C) 1998 Kluwer Academic Publishers.