Phase evolution in sonochemically synthesized Fe³⁺ doped BaTiO₃ nanocrystallites: structural, magnetic and ferroelectric characterisation

Abstract

The properties of nanomaterials are highly dependent on their size, morphology, crystal phase, etc., which in turn depend on the method of synthesis. We report here the electrical and magnetic characterisation of sonochemically synthesized Fe³⁺ doped nano BaTiO₃ samples. The dopant ion concentration has been optimized and the coexistence of ferromagnetism and ferroelectricity has been observed in the sample. With increase in Fe3+ doping from 0 to 20 mol%, a gradual phase change from tetragonal to hexagonal occurred in these sonochemically synthesized BaTiO₃ nanomaterials. Below 15 mol% Fe concentration the material displays ferroelectric behaviour with the absence of any magnetic ordering, while at an Fe concentration of ∼15 mol% the material exhibits both room temperature ferromagnetism and ferroelectricity. Ferromagnetism as well as relaxor type behaviour has been observed in the BaTiO₃:Fe³⁺(20%) sample. We have studied the ferromagnetic and ferroelectric ordering in these sonochemically synthesized Fe³⁺ doped BaTiO₃ nanomaterials and have tried to correlate the results with their crystal structure and morphology. The origin of ferromagnetism in these materials has been attributed to both intrinsic as well as extrinsic factors.