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

Abstract

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 Å at x = 0.25 and then it decreases almost linearly down to 5.886 Å at x = 1. The c parameter almost linearly increases from 23.216 Å up to 23.282 Å with x increasing. It has been discovered that titanium cations are located in the following positions: 4fIV tetrahedral and octahedral 4fVI 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 ~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 ~1 T. The saturation magnetization decreases from ~70.6 emu/g for x = 0.25 to ~56.7 emu/g for x = 1. The real part of the dielectric constant has value of ~0.2 for all the samples and gradually decreases at heating from room temperature up to ~500 K, after which it begins to increase sharply. The dielectric loss tangent has a maximum in the region of ~500 K and reaches a value of ~0.25 at a frequency of 104 Hz. With increasing the substitution level, the dielectric constant and the dielectric loss of all the samples increase.