Conformal nanocoating of zirconia nanoparticles by atomic layer deposition in a fluidized bed reactor

Hakim, Luis F.; George, Steven M.; Weimer, Alan W.

doi:10.1088/0957-4484/16/7/010

Cited by 110 publications

(78 citation statements)

References 44 publications

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“…Influence of pressure on coating time ALD on particles can be carried out at low pressure 6 as well as at atmospheric pressure. 43 The amount of rarefaction, i.e., the ratio between the mean free path and pore size, increases for decreasing pressure.…”

Section: Resultsmentioning

confidence: 99%

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Simulation of atomic layer deposition on nanoparticle agglomerates

Jin

Kleijn

Ommen

2016

Journal of Vacuum Science &Amp; Technology A: Vacuum, Surfaces, and Films

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Coated nanoparticles have many potential applications; production of large quantities is feasible by atomic layer deposition (ALD) on nanoparticles in a fluidized bed reactor. However, due to the cohesive interparticle forces, nanoparticles form large agglomerates, which influences the coating process. In order to study this influence, the authors have developed a novel computational modeling approach which incorporates (1) fully resolved agglomerates; (2) a self-limiting ALD half cycle reaction; and (3) gas diffusion in the rarefied regime modeled by direct simulation Monte Carlo. In the computational model, a preconstructed fractal agglomerate of up to 2048 spherical particles is exposed to precursor molecules that are introduced from the boundaries of the computational domain and react with the particle surfaces until these are fully saturated. With the computational model, the overall coating time for the nanoparticle agglomerate has been studied as a function of pressure, fractal dimension, and agglomerate size. Starting from the Gordon model for ALD coating within a cylindrical hole or trench [Gordon et al., Chem. Vap. Deposition 9, 73 (2003)], the authors also developed an analytic model for ALD coating of nanoparticles in fractal agglomerates. The predicted coating times from this analytic model agree well with the results from the computational model for Df = 2.5. The analytic model predicts that realistic agglomerates of O(109) nanoparticles require coating times that are 3–4 orders of magnitude larger than for a single particle.

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Section: Resultsmentioning

confidence: 99%

“…5 ALD coating on nanoparticles has been demonstrated in several experimental studies utilizing a fluidized bed. 6,7 In fluidized bed ALD, an amount of particles is suspended in an upward gas stream containing the precursor molecules. It is a useful technique for large scale processing of particles.…”

Section: Introductionmentioning

confidence: 99%

Simulation of atomic layer deposition on nanoparticle agglomerates

Jin

Kleijn

Ommen

2016

Journal of Vacuum Science &Amp; Technology A: Vacuum, Surfaces, and Films

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“…The system was operated at reduced pressures and under mechanical vibration. Deionized water and TMA (97 %, Sigma-Aldrich Co.) were used as reactants and the reaction temperature was 450 K. A detailed description of the experimental procedure for ALD coating of nanoparticles is included in previous publications by the authors [32][33][34].…”

Section: Methodsmentioning

confidence: 99%

“…[4,31] This technology has also been successfully applied to individually coat bulk quantities of various ceramic nanoparticles. [32][33][34] …”

Section: Introductionmentioning

confidence: 99%

Nanoparticle Coating for Advanced Optical, Mechanical and Rheological Properties

Hakim

King

Zhou

et al. 2007

Adv Funct Materials

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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.

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“…The CVD technique has been used in conjunction with fluidized beds to produce metal and metal-oxide coatings on fine particles (7)(8)(9). ALD has been used to produce thin films of alumina on a variety of particles in fluidized beds and most notably nanoparticles and polymers (10)(11)(12). Plasma coating techniques have also recently incorporated fluidized beds to coat small particles.…”

Section: Introductionmentioning

confidence: 99%

Fluidized Bed Sputtering for Particle and Powder Metallization

Baechle¹,

Demaree²,

Hirvonen³

et al. 2013

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Approved for public release; distribution is unlimited.ii REPORT DOCUMENTATION PAGE Form Approved OMB No. 0704-0188Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing the burden, to Department of Defense, Washington Headquarters Services, Directorate for Information Operations and Reports (0704-0188), 1215 Jefferson Davis Highway, Suite 1204, Arlington, VA 22202-4302. Respondents should be aware that notwithstanding any other provision of law, no person shall be subject to any penalty for failing to comply with a collection of information if it does not display a currently valid OMB control number. PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS. REPORT DATE (DD-MM-YYYY)April 2013 ARL-TR-6435 SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES) 10. SPONSOR/MONITOR'S ACRONYM(S) SPONSOR/MONITOR'S REPORT NUMBER(S) DISTRIBUTION/AVAILABILITY STATEMENTApproved for public release; distribution is unlimited. SUPPLEMENTARY NOTES ABSTRACTA system for sputter deposition of thin (10-1000 nm) metal and ceramic coatings onto vibro-fluidized beds of microparticles has been fabricated. Coatings are sputtered onto microparticles of various sizes, shapes, and materials. Experiments show that the coating deposition rate onto particles decreases with decreasing particle size for the case of a fixed total bed mass. Factors affecting particle coating thickness also include sputter power and fluidized bed container size. Coating surface morphology is evaluated using scanning electron microscopy. Lower sputter deposition powers create smoother, less porous coatings. Fluidizing parameters such as driving amplitude and frequency are also shown to affect coating morphology. Barrier coatings on salt microparticles are produced and shown to slow the dissolution of the coated salt particles in water. Dual-layer metalceramic coatings are also demonstrated using the sputter deposition technique. A dual-layer aluminum/tin-oxide coating is produced on glass microspheres, which are then shown to have distinct reflectance characteristics and colors. A model is developed to estimate coating thickness based on size, shape, and number of particles. iii

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Conformal nanocoating of zirconia nanoparticles by atomic layer deposition in a fluidized bed reactor

Cited by 110 publications

References 44 publications

Simulation of atomic layer deposition on nanoparticle agglomerates

Simulation of atomic layer deposition on nanoparticle agglomerates

Nanoparticle Coating for Advanced Optical, Mechanical and Rheological Properties

Fluidized Bed Sputtering for Particle and Powder Metallization

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