Influence of Na and Na/Fe doping on the dielectric constant, ferromagnetic and sunlight photocatalytic properties of BaTiO3 perovskite

Perovskite BaTiO3, Ba0.98Na0.02TiO3, Ba0.98Na0.02Ti0.97Fe0.03O3 and Ba0.98Na0.02Ti0.95Fe0.05O3 ceramics have been prepared by solid state reaction method. The XRD analysis of these compositions revealed that a single-phase was formed having tetragonal crystal structure. A contraction of the perovskite unit cell volume was observed upon incorporation of 2 at% Na and 3 or 5 at% Fe. This contraction confirms that Na+ ions substitute Ba2+ cation while Fe3+ ions replace Ti4+ of BaTiO3. Inclusion of Na+ ions into BaTiO3 increases the dielectric constant while Fe3+ codoping decreases it. On contrast, incorporation of Fe3+ ions enhances the ferromagnetic properties of BaTiO3. Na/Fe codoping leads to formation of oxygen vacancies in BaTiO3 accompanied by new energy bands in visible light region. We show the suitability of such band-engineered Na/Fe codoped BaTiO3 for sunlight photocatalytic application. The results of photocatalytic experiments showed that both Ba0.98Na0.02Ti0.97Fe0.03O3 and Ba0.98Na0.02Ti0.95Fe0.05O3 exhibit higher photocatalytic activity than undoped and Na doped BaTiO3.