Electrical transport and magnetoresistive properties of Nd-doped La0.8Sr0.2MnO3 ceramics

In this paper, La0.8−xNdxSr0.2MnO3 (x = 0.03, 0.04, 0.05, and 0.06) ceramics were synthesized by a sol–gel method. The structure, surface morphology, electrical transport, and magnetoresistive properties of these materials were studied. X-ray diffraction (XRD) revealed samples to be single-phase with a distorted perovskite structure belonged to the (R3¯c\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\text{R}}\bar 3{\text{c}}$$\end{document}) space group. Scanning electron microscopy (SEM) revealed the samples to contain compact grains, with the grain size increasing slightly with the amount of doping Nd3+. The standard four-probe method was used to test the electrical resistivity of the samples as a function of temperature (ρ–T). The metal–insulator transition temperature (Tp) shifted to lower temperatures and the resistivity (ρ) increased with the content of Nd3+. Peak temperature coefficient of resistance (TCR) and magnetoresistance (MR) were both affected by the Nd3+ substitution. At x = 0.05, peak TCR and MR reached 5.12% K−1 and 19.78%, respectively. The mechanism responsible for both electrical and magnetoresistive properties of these materials was discussed in the frame of double-exchange (DE) interaction.