Low-temperature synthesis, structure and magnetoresistance of submicrometric La_1-xK_xMnO_3+δ perovskites

Abstract

The use of a precursor-based synthetic method, namely, the freeze-drying of acetic acid solutions, allows the preparation, at temperatures as low as 600 °C, of single phase perovskites in the solid solution series La_1-xK_x MnO_3+δ. This soft treatment of the precursors yields products constituted of homogeneous nanometric particles (30–50 nm). Samples prepared at 1000 °C remain single phase forx=0.00, 0.05, 0.10 and 0.15, and are constituted by submicrometer homogeneous particles, without deviation from nominal stoichiometries upon heating. Their crystal structures were refined by the Rietveld method from X-ray powder diffraction data. Ac susceptibility, magnetization, resistivity and magnetoresistivity measurements have allowed us to establish, for the first time, relevant points of the electronic phase diagram of an alkali-metal-doped lanthanide manganate system.

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