The study of structural, dielectric, impedance and modulus properties of La0·8Pb0·2FeO3 doped by 25% Mg into the B-site

The sample of La0·8Pb0·2Fe0·75Mg0·25O3 was synthesized via the sol-gel route. The Refinement using the Rietveld method confirms that the structure is orthorhombic with space group Pnma. The dielectric properties (ε) and modulus (M) of the material were studied a wide range of temperatures and frequencies range. The constant dielectric values of our compound were lower than those for LaFeO3. Indeed, relatively reduced values of the dielectric constant, not exceeding 102 F/m, were usually achieved when intrinsic ionic and electronic polarization mechanisms were employed in the studied structure. Dielectric losses were described by the Giuntini theory. The imaginary modulus spectra were adjusted using the exponential function provided by Kohlrausch-Williams Watts (KWW) relaxation function, which determined the presence of thermally activated relaxation. The comparative display of the normalized impedance and electric modulus revealed the existence of short-range movement of the charge carrier. Relaxation phenomena of the non-Debye type were confirmed in the material by studying the modulus.