Nanoblast Synthesis and Consolidation of (La_0.8Sr_0.2)(Ga_0.9Mg_0.1)O_3– Under Spark Plasma Sintering Conditions

Four-cation nanograined strontium and magnesium doped lanthanum gallate (La_0.8Sr_0.2) · (Ga_0.9Mg_0.1)O_3– (LSGM) and its composite with 2 wt% of ceria (LSGM-Ce) were prepared. Morphologically homogeneous nanoreactors, i.e., complex intermediate metastable aggregates of desired composition were assembled by spray atomization technique, and subsequently loaded with nanoparticles of highly energetic C₃H₆N₆O₆. Rapid nanoblast calcination technique was applied and the final composition was synthesized within the preliminary localized volumes of each single nanoreactor on the first step of spark plasma treatment. Subsequent SPS consolidations of nanostructured extremely active LSGM and LSGM-Ce powders were achieved by rapid treatment under pressures of 90–110 MPa. This technique provided the heredity of the final structure of nanosize multimetal oxide, allowed the prevention of the uncontrolled agglomeration during multicomponent aggregates assembling, subsequent nanoblast calcination, and final ultra-rapid low-temperature SPS consolidation of nanostructured ceramics. LaSrGaMgCeO_3– nanocrystalline powder consisting of ∼11 nm crystallites was consolidated to LSGM-Ce nanoceramic with average grain size of ∼14 nm by low-temperature SPS at 1250 °C. Our preliminary results indicate that nanostructured samples of (La_0.8Sr_0.2)(Ga_0.9Mg_0.1)O_3– with 2 wt% of ceria composed of ∼14 nm grains can exhibit giant magnetoresistive effect in contrast to the usual paramagnetic properties measured on the samples with larger grain size.