Nanoparticle Coating for Advanced Optical, Mechanical and Rheological Properties

Abstract

Primary titania nanoparticles were coated with ultrathin alumina films using Atomic Layer Deposition (ALD). The deposited films were highly uniform and conformal with an average growth rate of 0.2 nm per coating cycle. The alumina films eliminated the surface photocatalytic activity of titania nanoparticles, while maintained their original extinction efficiency of ultraviolet light. Deposited films provided a physical barrier that effectively prevented the titania surface from oxidizing organic material whereas conserving its bulk optical properties. Parts fabricated from coated powders by pressureless sintering had a 13 % increase in surface hardness over parts similarly fabricated from uncoated particles. Owing to its homogeneous distribution, the secondary alumina phase suppressed excessive grain growth. Alumina films completely reacted during sintering to form aluminum titanate composites, as verified by XRD. Coated particles showed a pseudoplastic behavior at low shear rates due to modified colloidal forces. This behavior became similar to the Newtonian flow of uncoated nanoparticle slurries as the shear rate increased. Suspensions of coated particles also showed a decreased viscosity relative to the viscosity of uncoated particle suspensions.

Atomic Layer Deposition of UV‐Absorbing ZnO Films on SiO2 and TiO2 Nanoparticles Using a Fluidized Bed Reactor

“…[15] Various oxide materials have been deposited on particle substrates using ALD methods. [16][17][18][19] The metalorganic precursor diethylzinc (DEZ) is used for ZnO thin film deposition on particles, with deionized H 2 O as the oxidizer, and is typically operated at 450K, or 177 8C. [17] The binary CVD reaction for ZnO deposition is:…”

H2 generation from thermochemical water-splitting using yttria stabilized NiFe2O4 core-shell nanoparticles

“…To the best of our knowledge, this is the first study that reports H 2 generation via thermochemical water-splitting using core-shell nanoparticles. As such there are a number of synthesis methods available to prepare core-shell nanoparticles which include solvothermal reaction, 31 one-step alkoxide hydrolysis, 32 sol-gel, 33,34 polymeric precursor coating, 35 hydrothermal, 36 atomic layer deposition (ALD), 37,38 and molecular layer deposition (MLD). 39 Among these methods, sol-gel 40,41 techniques are relatively simple to apply and provide for the synthesis of core-shell particles.…”

Synthesis, Characterization, and Antibacterial Activity of Silver-Doped Silica Nanocomposite Particles

“…[1][2][3] The composite structure gives rise to synergistic physical and chemical properties that are not easily attainable from single-phase material or from mixing of materials with different chemistries. [4][5][6] Considerable success has been achieved in terms of the variety of well-defined particulate structure and the versatility of their synthesis process. In view of the literature, coreshell fluorescent silica nanoparticles of different diameters and with inclusions of organic dye molecules of various colors have been developed for emerging nanomedicine applications.…”