Dielectric relaxation and ac conduction in multiferroic TbMnO sub(3) ceramics: Impedance spectroscopy analysis

• Published in: Current applied physics Vol. 14; no. 11; pp. 1492 - 1497
• Main Authors: Izquierdo, J L, Bolanos, G, Zapata, V H, Moran, O
• Format: Journal Article
• Language: English
• Published: 01.11.2014
• Subjects: Aluminum; Constants; Emergence; Fittings; Grains; Impedance; Impedance spectroscopy; Mathematical models
• ISSN: 1567-1739
• DOI: 10.1016/j.cap.2014.08.012

Polycrystalline samples of Tb sub(1-x)Al sub(x)MnO sub(3) (x = 0, 0.1, 0.2) have been synthesized by means of standard high-temperature solid-state reaction technique. Detailed studies on the effect of compositional variation of aluminum (Al) on the electrical behavior (complex impedance Z*, complex modulus M*, and relaxation mechanisms) of the parent TbMnO sub(3) have been performed by using the nondestructive complex impedance spectroscopy technique at temperatures above room temperature. In the temperature range covered, the impedance plots signalize that the grains are the unique responsible for the conduction mechanism of the concerned material. The impedance spectra are well modeled in terms of electrical equivalent circuit with a grain resistance (R sub(g)) and constant phase element impedance (Z sub(CPE)). The conductivity data of the undoped and Al-doped samples are well fitted by the universal Jonscher's power law. The resulting fitting parameters indicate that for the studied samples, the hopping process occurs between neighboring sites. Activation energy values for dc conductivity are calculated for undoped and Al-doped samples and found to decrease when Al is incorporated. In turn, the emergence of single arc in the complex modulus spectrum for all the compositions of Al suggests that for the studied samples only one type of relaxation behavior is present at the selected temperatures. A non-Debye-type relaxation is clearly verified. The relaxation process in the present samples seems to be composition and temperature dependent, particularly at higher frequencies.