TiO₂–SiO₂ nanocomposite thin films deposited by direct liquid injection of colloidal solution in an O₂/HMDSO low-pressure plasma

Abstract

TiO2 nanoparticles (NPs), 3 nm in size, were injected inside a very-low-pressure O2 plasma reactor using a liquid injector and following an iterative injection sequence.Simultaneously, hexamethyldisiloxane (HMDSO) vapor precursor was added to create a SiO2 matrix and a TiO2-SiO2 nanocomposite (NC) thin film. Both the liquid injection and vapor precursor parameters were established to address the main challenges observed when creating NCs. In contrast to most aerosol-assisted plasma deposition processes, Scanning/Transmission Electron Microscopy (S/TEM) indicated isolated (i.e. non-agglomerated) NPs distributed in a rather uniform way in the matrix. The fraction of the TiO2 NPs inside the SiO2 matrix was estimated by SEM, Spectroscopic Ellipsometry (SE), and X-ray Photoelectron Spectroscopy.All techniques provided coherent values, with percentages between 12 and 19%. Despite the presence of TiO2 NPs, SE measurements confirmed that the plasma-deposited SiO2 matrix was dense with an optical quality similar to the one of thermal silica. Finally, the percentage of TiO2 NPs inside the SiO2 matrix and the effective refractive index of the NCs can be tuned through judicious control of the injection sequence.

A Versatile Route for Synthesis of Metal Nanoalloys by Discharges at the Interface of Two Immiscible Liquids

“…Furthermore, it is worthy to note that the production of the matrix, simultaneously with the nanoparticles, reduces the particle-particle interactions, which prohibits their agglomeration. Such characteristic is extensively searched for, especially in the field of deposition of multifunctional nanocomposite thin films [ 47 , 48 ]. Note that the production of nanoalloys using the present process may be used in other processes to obtain devices with specific properties (e.g., catalytic properties).…”

Hybrid approaches coupling sol–gel and plasma for the deposition of oxide-based nanocomposite thin films: a review

“…Brunet et al [114] attempted to control the coverage percentage through the power supply frequency of the DBD (adjusting the process), whereas Fanelli et al [109] chose to increase the NPs concentration in the solution (by adjusting the precursor). Finally, we [134] showed that it was possible through a specific approach and particularly by optimizing the sequence of injection to tune the TiO 2 NPs content up to 58% while achieving tunable optical properties of the film.…”

“…As for the most recent reports, our group [134] attempted for the first time the pulsed injection of the colloidal solution (laboratory-made) [135] [136] in much lower-pressure plasma system such as 3 mTorr. The objective of this study was to elaborate TiO 2 -SiO NC thin films though a versatile and agile hybrid process.…”

“…The second work was from Ross et Gleason [126] where the colloidal solution with the NPs was injected simultaneously with the HMDSO vapor precursor in the low-pressure (100-500 mTorr) plasma reactor (RF CCP). The third work was from our group [134] where the TiO 2 NP colloidal solution was introduced simultaneously with the HMDSO vapor precursor of the matrix in the low-pressure 3 mTorr O 2 plasma reactor (RF ICP).…”

Functionalities and modification of sol–gel derived SiO₂–TiO₂ systems for advanced coatings and powders

“…16) 24) Another effective technique to improve the properties of TiO 2 NPs is to disperse them in a host matrix that has favorable characteristics, such as a large surface area, high light transmittance, and durability, to form a nanocomposite that combines two or more nanomaterials. 25) Among the available matrices, silica (SiO 2 )-based glass and gels (siloxanes and silsesquioxanes) meet all the abovementioned physical and chemical requirements. As a result, SiO 2 TiO 2 nanocomposites have been developed to exhibit superior mechanical, optical, and physicochemical properties to those of TiO 2 NPs.…”