Structural analysis of nanocrystalline BaTiO3

Barium titanate with powder particles having a diameter of about 50 nm, which was prepared by sol–gel-hydrothermal reaction, was studied using several experimental techniques for the determination of the crystalline phase and purity of synthesized BaTiO3. The results of XRD and Raman spectroscopy were contradictory with respect to the nature of the formed phase for the barium titanate nanocrystals. The first indicated the formation of a cubic phase and the second indicated that was tetragonal. Thus, we use a combination of experiments, especially Raman spectroscopy supported by density functional theory calculations and measurement of the ferroelectric behavior, which showed the formation of a tetragonal phase. In addition, from theoretical calculations suggested that the ferroelectric nature, present only in the tetragonal phase, can arise from a small displacement of the titanium atom along the Z-axis from ⩾0.5 pm, leaving from a cube phase to obtain pseudo cubic or slightly tetragonal phases.