Influence of titanium substitution on structure, magnetic and electric properties of barium hexaferrites BaFe12-xTixO19

Titanium substituted BaFe12-xTixO19 (x <= 1) barium hexaferrites have been synthesized using the solid phase method. The phase purity and the crystal structure of the obtained solid solutions have been studied by X-ray diffraction. It was found that the unit cell parameters change a non-monotonically. The a parameter has a maximum of 5.896 angstrom at x = 0.25 and then it decreases almost linearly down to 5.886 angstrom at x = 1. The c parameter almost linearly increases from 23.216 angstrom up to 23.282 angstrom with x increasing. It has been discovered that titanium cations are located in the following positions: 4fIV tetrahedral and octahedral 4f(VI) and 12k ones. Results of the Mossbauer and Raman spectrometry confirm the established substitution mechanism. The homogeneous ferrimagnetic ordering is detected by magnetic measurements down to similar to 35 K. Below this temperature the noncollinear magnetic structure is formed as a result of Fe2+ cations change in the spin state from high to low configuration. Magnetization for all the samples is saturated at room temperature in fields of similar to 1 T. The saturation magnetization decreases from similar to 70.6 emu/g for x = 0.25 to similar to 56.7 emu/g for x = 1. The real part of the dielectric constant has value of similar to 0.2 for all the samples and gradually decreases at heating from room temperature up to similar to 500 K, after which it begins to increase sharply. The dielectric loss tangent has a maximum in the region of similar to 500 K and reaches a value of similar to 0.25 at a frequency of 10(4) Hz. With increasing the substitution level, the dielectric constant and the dielectric loss of all the samples increase.