Regular Article

Chemical disorder induced positive magnetoimpedance in La_0.7Pb_0.3Mn_0.35Fe_0.65O_3−δ and La_0.7Pb_0.3Mn_0.3Fe_0.7O_3−δ manganites

¹ Materials Chemistry Laboratory, Centre of Material Sciences, University of Allahabad, Prayagraj (Allahabad) 211002, India
² UGC DAE Consortium for Scientific Research, University Campus, Khandwa Road, Indore 452017, India

^* e-mail: brajendr@allduniv.ac.in, brajendr@gmail.com

Received: 21 October 2020
Received in final form: 11 February 2021
Accepted: 8 March 2021
Published online: 30 March 2021

Abstract

We report structural, magnetic and magnetoimpedance properties of La_0.7Pb_0.3Mn_0.35Fe_0.65O_3−δ and La_0.7Pb_0.3Mn_0.3Fe_0.7O_3−δ manganites. Bulk samples were prepared by solid state method. Rietveld refinement of the X-ray diffraction pattern shows the crystallization of these samples in trigonal crystal system. Fe doping at Mn site in La_0.7Pb_0.3MnO₃ increases the lattice parameters and induces oxygen non stoichiometry in the lattice of La_0.7Pb_0.3Mn_0.35Fe_0.65O_3−δ and La_0.7Pb_0.3Mn_0.3Fe_0.7O_3−δ. La_0.7Pb_0.3Mn_0.3Fe_0.7O_3−δ composition shows ∼180% positive magnetoimpedance at 1 Tesla magnetic field while La_0.7Pb_0.3Mn_0.35Fe_0.65O_3−δ shows ∼75% positive magnetoimpedance at 320 K. Magnetization versus applied magnetic field measurement curves show the magnetic moment of La_0.7Pb_0.3Mn_0.35Fe_0.65O_3−δ and La_0.7Pb_0.3Mn_0.3Fe_0.7O_3−δ do not saturate up to 2 tesla magnetic field at 300 K. Fe⁺³ doping at Mn site in these manganites created chemically modified phase separated systems. Huge positive magnetoimpedance in 65% and 70% Fe doped manganites originated by maxwell wagner effect due to the chemical disorder induced phase separated states and dominated coulombic interactions.