Dielectric Properties and Magnetoelectric Effect of Bi₇Fe₃Ti₃O₂₁ Ceramic Material Doped with Gadolinium Ions

Pure Bi7Fe3Ti3O21 ceramic material and gadolinium ion (Gd3+)-doped ones were prepared by solid-state reaction method using simple oxides. The findings of the XRD measurements confirmed the initial author’s assumption that the dopant ions substituted in perovskite blocks influenced the dimensions of the unit cell parameters. All obtained materials are single-phase and show an orthorhombic structure with the Fm2m space group. Microstructure studies show that the admixture gadolinium doping changes the microstructure of the base material, changing grain shapes from plate-like to rounded. The temperature dependences of the electric permittivity have shown the existence of a maximum, the temperature location of which depends on both the frequency and the concentration of Gd3+ ions. The highest values of electric permittivity were characteristic of the material with an admixture of Gd3+ ions in the amount of x = 0.6 (f = 1 kHz), and the lowest values were for material with x = 0.2 (f = 1 kHz). Studies of the magnetoelectric effect have shown that the strongest coupling between magnetic and electrical properties was demonstrated by a material doped with Gd3+ ions in the amount of x = 0.2, for which the magnetoelectric coupling coefficient is equal to α = 12.58·10−9 s/m.