Ion implantation-induced nanoscale particle formation in Al2O3 and SiO2 via reduction

A novel method for creating nano-dimensional metallic precipitates in oxide materials using the technology of ion implantation is reported. The reduct ion of single-crystalline alumina to Al and fused silica to Si is induced b y ion implantation with ions which are selected in accordance with the laws of thermodynamics. The Al and Si resulting from reduction subsequently clu ster and react with other elements to form nano-dimensional precipitates. T he implantation of 150 keV Y+ and Ca+ into alumina to a fluence of 5 x 10(1 6) ions/cm(2), results in Al particles with an average diameter of 12.5 nm and 8.0 nm, respectively. Alumina implanted with Mg+ at the same ion energy and fluence forms MgAl2O4 platelets ranging from 5 to 10 nm in width and b etween 15 and 40 nm in length. The implantation of silica with 160 keV Zrions to a fluence of 1 x 10(17) Zr+/cm(2) results in the formation of ZrSi2 particles ranging in size between 1 and 17 nm. Consistent with thermodynam ic predictions, control implants of Cr+ and Si+ in alumina and Cr+ in silic a do not result in the formation of particles that contain elements origina lly present in the substrate. (C) 1999 Acta Metallurgica Inc. Published by Elsevier Science Ltd. All rights reserved.