EFFECT OFNiON THE ELECTRICAL AND MICROSTRUCTURAL PROPERTIES OF NANOCRYSTALLITESFe2O3/TiO2SYSTEM

Nominal compositions ofNixTi1-xFe2O5-δ(x = 0, 0.2, 0.4, 0.6, 0.8 and 1) were prepared by a solid state reaction using stoichiometric amounts ofFe2O3/TiO2system andNiOas a dopant. The effects of small substitution ofNiions on the electrical and structural properties were studied for the above system. The X-ray diffraction patterns revealed that the ferroelectric phase of iron titanate and the spinel ferrite phase ofNi-ferrite having a single phase atx = 0and 1, respectively. The substitution ofNiions increases the average value of lattice constant aav. Solid–solid interaction took place between the ternary oxides at 1200°C for 4 h yielding a new phase ofNiTiO3. The presence of the three phases was confirmed by X-ray diffraction technique. The resultant compositions have nanocrystallites with average crystalline size "Dav" in the range 100–300 nm. The DC electrical resistivity ρ, Curie temperatureTCand activation energies for electric conduction aroundTCregion increase asNiion substitution increases. The ferrite samples have a semiconductor behavior where electrical resistivity ρ decreases on increasing temperature. The activation energy for electrical conduction was affected by both the ratio "ferroelectric/ferrite" and the position of the Curie temperatures in the compositions depending on the (Ni,Ti) toFeratio.