THE PREPARATION OF IRON COMPLEX OXIDE NANOPARTICLES BY PULSED-LASER ABLATION

Nanoparticles of a calcium-iron complex oxide were prepared by pulsed laser ablation on silicon wafer substrates placed at off-axial positio ns against a target. An ArF excimer laser was used to irradiate a CaFe 2O4 target in atmospheres of Ar and O-2 at room temperature. The effec ts of ambient pressure and laser pulse energy on size and composition of nanoparticles were investigated using atomic force microscopy and X -ray photoelectron spectroscopy. The nanoparticles obtained were almos t spherical and 2 to 26 nm in diameter. The size distributions of the nanoparticles were were narrow and agreed with the log-normal distribu tion function. The nanoparticle size increased with ambient pressure a nd pulse energy. The Ca/Fe atomic ratios in the nanoparticles, however , decreased with increasing ambient pressure and were independent of p ulse energy. By this technique, the size and composition of nanopartic les can be easily controlled by laser fluence and pressure during the laser ablation. (C) 1998 Elsevier Science B.V.