Single-phase La-1.2(Sr1.4Ca0.4)Mn2O7 has been synthesized from the aqueous solution of metal nitrates and citric acid by the sol-gel technique. Small particle size with high homogeneity of the powder was obtained. The valence of Mn is determined to be 3.45 +/- 0.05 by chemical titration. The MR ratio [rho - rho(H)]/rho(H), is 115% (102 K, 1.5 T) for the composition prepared by the citrate route, and is nearly three times larger than that of the sample prepared by solid state reaction. (C) 2002 Elsevier Science Ltd. All rights reserved.
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MATERIALS RESEARCH BULLETIN Volume: 37 Issue: 2 Pages: 235-246
