Study of mechanical and dielectric spectrum in YFe_1-xMn_xO₃ceramics

The mechanical spectra of Mn-substituted yttrium orthoferrite YFe1-xMnxO3(x = 0, 0.2, 0.3, 0.4) ceramics were performed at kilohertz from 100 to 360 K. Two internal friction (IF) peaks are observed around 150 K and 230 K, respectively, and both the IF peaks exhibit frequency dispersion behavior. The IF peak around 150 K is associated with a step increase in the modulus and its mechanical relaxation rate follows the Vogel-Fulcher relation with τ0= 4.45 × 10-11s, Eα= 0.03 eV, and TVF= 155 K. This IF peak can be explained in terms of a freezing of oxygen vacancies after excluding the possible magnetic spin glass transition. Another IF peak around 230 K presents a relaxation behavior and it follows Arrhenius law. Furthermore, the relaxation behavior was verified by the dielectric spectrum and it can be ascribed to the charge carrier hopping between Fe2+and Fe3+.