Study on mechanical, dielectric and magnetic properties of Pr1- xSr xFeO3 ceramics.

The mechanical spectra of Pr_{1- x}Sr _xFeO_{3- δ} ( x = 0.5, 0.55, and 0.6) ceramics were performed at kHz frequencies from 100 to 350 K. An internal friction (IF) peak associated with modulus defect around 130 K and a modulus kink at 200 K were observed. This IF peak temperature shows frequency-dispersive behavior. The dielectric spectra and magnetization measurements were used to clarify the origin of the anomaly in IF and modulus. The dielectric spectra provide clear evidence for the relaxation behavior of IF peak and the activation energies of 0.14, 0.13, and 0.11 eV were derived from the Arrhenius law for Pr_0.5Sr_0.5FeO₃, Pr_0.45Sr_0.55FeO₃, and Pr_0.4Sr_0.6FeO₃ samples, respectively. The relaxation behavior is ascribed to the charge-carrier hopping between Fe³⁺ and Fe⁴⁺. Furthermore, the magnetization measurement confirms that the kink in the reduced Young's modulus is associated with a spin-glass transition. In addition, another dielectric anomaly at 200 K may be related to the magneto dielectric effect. [ABSTRACT FROM AUTHOR]