Nanocomposite formed by titanium ion implantation into alumina

Abstract

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, φ0, the maximum implantation dose for which the nanocomposite material still remains a composite, is φ0 = 2.2 × 1016 cm−2, and the corresponding saturation conductivity is σ0 = 480 S/m. The percolation dose φc, below which the nanocomposite still has basically the conductivity of the alumina matrix, was found to be φc = 0.84 × 1016 cm−2. The experimental results are discussed and compared with a percolation theory model.

Influence of Annealing on the Dielectric Properties of Zn-SiO2/Si Nanocomposites Obtained in “Hot” Implantation Conditions

“…Compared to other techniques, such as chemical vapor deposition (CVD) [5], molecular beam epitaxy (MBE) [6], sol-gel synthesis [7] and pulsed laser deposition [8], ion implantation has several important advantages, including no synthesis-related impurities and precise control of the introduced metal ions and their depth distribution in the dielectric matrix [9]. Accordingly, nanoparticles of metals and metal oxides, such as copper (Cu) [10], gold (Au), nickel (Ni) [11], silver (Ag) [12], cobalt (Co) [13], etc., were synthesized by ion implantation in dielectrics such as SiO 2 [14], Al 2 O 3 [15], and even in MgO [16,17] or CeO 2 [13]. According to the literature sources, in the SiO 2 matrix, the implanted ions form spherical nanoparticles with a random distribution [14].…”

Testes e aplicação de um novo implantador iônico.

“…Os métodos físicos incluem a ablação por laser, deposição química a vapor, fluidos supercríticos dentre outros [39]. A implantação iônica também tem sido utilizada para gerar camada de nanocompósito alguns nanômetros abaixo da superfície do substrato [12,[40][41][42][43][44][45][46][47][48][49][50][51][52][53][54]. Como já mencionado no Capítulo 2, a formação das nanopartículas metálicas se dá espontaneamente e pode ser explicada pela ocorrência de concentração dos átomos metálicos acima do limite de solubilidade no substrato implantado, levando à nucleação e crescimento das nanopartículas metálicas [27].…”

“…O implantador invertido foi utilizado para modificação de superfície de alumina, gerando uma camada de nanocompósito logo abaixo de sua superfície, formada por nanopartículas de titânio na matriz de alumina [53].…”