Abstract

A soft chemistry process to prepare La_0.7Sr_0.3MnO₃ (LSMO)/silica hybrid nanocomposites is reported. Homogeneous granular mixtures are obtained through a sol–gel chemical route by a single step. The precursor solution is comprised of complexes of La³⁺, Sr²⁺ and Mn²⁺ with ethylenediaminetetraacetic acid (EDTA) and tetraethoxysilane (TEOS). Silica is produced by an ammonia-catalyzed process, and LSMO is obtained by thermal decomposition of the complex precursor. Micrographs from scanning electron microscopy show well homogeneous solid mixtures of the two phases at the nanoscale level. XRD patterns and micro-FTIR analysis indicate that SiO₂ exists in the composites independent of LSMO when calcined at low temperature, whereas Si–O–M (M = La, Sr and Mn) bonds are formed upon calcination above 800 °C. An enhanced magnetoresistance is observed for a 700 °C-calcined (LSMO)(SiO₂)_0.20 composite from 150 K up to room temperature.