Microwave assisted synthesis of manganese mixed oxide nanostructures using plastic templates

The synthesis method for obtaining sub-micrometric structures of rare earth manganese-based mixed oxide compounds is described. Pore wetting of porous polycarbonate templates with the liquid precursor was followed by a two-stage thermal treatment to obtain single phase La 0.325Pr 0.300Ca 0.375MnO 3 hollow and solid structures, with external diameter determined by the sacrificial template pore size. The first thermal stage, a microwave assisted denitration process, determines the shape of the structures. The second treatment, performed at 1073 K, allows to obtain the crystallographic structure of the compound. A variety of techniques (scanning and transmission electron microscopy, scanning probe microscopy) allowed to fully characterize the microstructure and morphology of these self-standing manganite nanostructures. For 1 μm pore size templates we obtained tubes, with external diameter around 800 nm and wall thickness around 150 nm; densely packed nanoparticles sized 20-50 nm are the building blocks of the walls. For pore size below 0.1 μm, solid nanowires were obtained, the size of constituent crystallites being around 10 nm. Overall obtained material exhibits ferromagnetic ordering below 200 K. Micrograph of tubular structures of La 0.325Pr 0.300Ca 0.375MnO 3 grown in a 1 micron pore size policarbonate template. © 2004 Elsevier Inc. All rights reserved.