Preparation of manganite perovskites by a wet-chemical method involving a redox reaction and their characterisation

Philip, John and Kutty, TRN (2000) Preparation of manganite perovskites by a wet-chemical method involving a redox reaction and their characterisation. In: Materials Chemistry and Physics, 63 (3). pp. 218-225.

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Abstract

Manganite perovskites compounds are prepared through a wet-chemical technique. Here the hydrated $MnO_2$ is precipitated first from Mn(VII) and Mn(II) salts using a redox reaction in nitric acid medium. Hydrated $MnO_2$ is black in colour, has large porosity and high surface area $> 120 m^2/g$ and acts as a precursor for the preparation of manganite perovskites. Thermogravimetric studies show that the $MnO_2$ phase changes to $MnO_2O_3$ upon heating to 783 K. Various perovskite compounds have been prepared, all compositions exhibit high concentration of $Mn^{4+}$ ions. Transmission electron microscopy showed the presence of well-facted crystallites of Ca-, Ba-substituted $LaMnO_3$ and their size ranges from 100 to 400 nm. Resistivity, thermopower and magnetoresistance studies are carried out for the composition $La_{0.667}Ca_{0.333}MnO_3$ which displayed a large magnetoresistance coefficient $(\sim 0.8)$ in a magnetic field of 1 T.

Item Type:	Journal Article
Publication:	Materials Chemistry and Physics
Publisher:	Elsevier
Additional Information:	Copyright of this article belongs to Elsevier
Keywords:	Lanthanum calcium manganite;Magnetoresistance;Redox reaction;Co-precipitation.
Department/Centre:	Division of Chemical Sciences > Materials Research Centre
Date Deposited:	08 Oct 2008 07:49
Last Modified:	19 Sep 2010 04:51
URI:	http://eprints.iisc.ac.in/id/eprint/16243

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