Nanocomposite formed by titanium ion implantation into alumina

Composites of titanium nanoparticles in alumina were formed by ion implantation of titanium into alumina, and the surface electrical conductivity measured in situ as the implantation proceeded, thus generating curves of sheet conductivity as a function of dose. The implanted titanium self-conglomerates into nanoparticles, and the spatial dimensions of the buried nanocomposite layer can thus be estimated from the implantation depth profile. Rutherford backscattering spectrometry was performed to measure the implantation depth profile, and was in good agreement with the calculated profile. Transmission electron microscopy of the titanium-implanted alumina was used for direct visualization of the nanoparticles formed. The measured conductivity of the buried layer is explained by percolation theory. We determine that the saturation dose, phi(0), the maximum implantation dose for which the nanocomposite material still remains a composite, is phi(0) = 2.2 x 10(16) cm(-2), and the corresponding saturation conductivity is sigma(0) = 480 S/m. The percolation dose phi(c), below which the nanocomposite still has basically the conductivity of the alumina matrix, was found to be phi(c) = 0.84 x 10(16) cm(-2). The experimental results are discussed and compared with a percolation theory model. (C) 2014 AIP Publishing LLC.