# Magnetoresistive studies on nanocrystalline $La_{0.8}Sr_{0.2}MnO_{3+\delta}$ manganite

Nagabhushana, BM and Chakradhar, Sreekanth RP and Ramesh, KP and Prasad, V and Shivakumara, C and Chandrappa, GT (2008) Magnetoresistive studies on nanocrystalline $La_{0.8}Sr_{0.2}MnO_{3+\delta}$ manganite. In: Physica B: Condensed Matter, 403 (19-20). pp. 3360-3364.

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## Abstract

Low-temperature magnetoresistance (MR) measurement has been carried out on nanocrystalline $La_{0.8}Sr_{0.2}MnO_{3+\delta}$ manganites prepared by combustion synthesis. This preparation method yields voluminous powders with large surface area $(\sim40m^2/g)$ having crystalline nanosize $(\sim50 nm)$ products. Formation and homogeneity of the solid solutions have been confirmed by powder X-ray diffraction (PXRD), scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS). Rietveld refinement of X-ray data indicates that as-formed compound exhibits cubic phase with space group Pm3m. However, calcined sample transforms into rhombohedral phase with space group R-3c. The stabilization of the cubic phase in as-formed manganite is due to the substitution of $Sr^{2+}$ on $La^{3+}$ sites, resulting in higher $Mn^{4+}$ content. The low-temperature resistivity measurements down to 70K exhibit a broad metal–insulator transition $(T_{M-I})$ at around 257 K. MR measurements on sintered pellets show $\SIM 5\%$ MR at 1 T, whereas for 4 and 7 T, the %MR values are found as 22% and 28%, respectively, at $T_{M-I}$.

Item Type: Journal Article Copyright of this article belongs to Elsevier. Oxides;Chemical synthesis;X-ray diffraction;Magnetic properties. Division of Chemical Sciences > Solid State & Structural Chemistry UnitDivision of Physical & Mathematical Sciences > Physics 13 May 2009 04:50 19 Sep 2010 04:51 http://eprints.iisc.ernet.in/id/eprint/16374