Synthesis of titanium-oxide nanoparticles with size and stoichiometry control

Abstract

Ti-O nanoparticles have been synthesized via hollow cathode sputtering in an Ar-O-2 atmosphere using high power pulsing. It is shown that the stoichiometry and the size of the nanoparticles can be varied independently, the former through controlling the O-2 gas flow and the latter by the independent biasing of two separate anodes in the growth zone. Nanoparticles with diameters in the range of 25-75 nm, and with different Ti-O compositions and crystalline phases, have been synthesized.<p>Funding Agencies|Knut and Alice Wallenberg foundation [KAW 2014.0276]; Swedish Research Council via the Linkoping Linneaus Environment LiLi-NFM [2008-6572]</p

The influence of pressure and gas flow on size and morphology of titanium oxide nanoparticles synthesized by hollow cathode sputtering

“…When the growth tube was present no change in the discharge voltage could be seen, even for oxygen partial pressures of 1.25 Pa. This can be compared to our previously published paper 3 , where fully stoichiometric titanium dioxide particles where synthesized at an oxygen partial pressure of 0.04 Pa. From this result we can conclude that no contaminants outside of the growth tube were able to react with the hollow cathode and the contaminants present were those that desorbed from the growth tube walls or permeated from outside of the chamber through the cathode holder. This leads to a more stable process over time, as well as a smaller influence of the increased partial pressure of contaminants when the pumping speed is restricted.…”

“…This resulted in pulses with voltages of approximately 290 V and peak discharge currents of approximately 10 A. These were the same parameters used in our previous paper 3 and were found to give a stable partial pressure of oxygen during reactive sputtering. The main process gas, Ar, was fed through the hollow cathode after passing through a gas purifier (UltraPure).…”

“…3 This finding is however different from those done by Hanu et al 18 who observed a size decrease and Ahadi et al 19 who observed a size increase. The size increase was attributed to an increased coagulation of the particles when oxygen was added to the process.…”

Nucleation of titanium nanoparticles in an oxygen-starved environment. I: experiments

“…Finally, no nanoparticles were found in pure helium, i. e., without any argon gas flow. This "zero-flow" limit to is marked (4).…”

Molhabilidade e atividade fotocatalítica de filmes finos de TiOx depositados por magnetron sputtering em diferentes pressões parciais de O2

“…A estrutura eletrônica pode ser alterada pela deficiência de oxigênio. Além disto, as vacâncias de oxigênio na superfície desempenham papel relevante na fotocatálise em soluções aquosas, uma vez que moléculas de água podem ser dissociadas nestas vacâncias (6,8) . A concentração de oxigênio no filme pode ser controlada através da pressão parcial de O 2 durante o processo de deposição por magnetron sputtering, em atmosfera de Ar+O 2 , permitindo obter diferentes filmes de TiO x .…”