The atomic layer deposition (ALD) of Al 2 O 3 using sequential exposures of Al(CH 3 ) 3 and O 3 was studied by in situ transmission Fourier transform infrared (FTIR) spectroscopy and quadrupole mass spectrometry (QMS). The FTIR spectroscopy investigations of the surface reactions occurring during Al 2 O 3 ALD were performed on ZrO 2 particles for temperatures from 363 to 650 K. The FTIR spectra after Al(CH 3 ) 3 and ozone exposures showed that the ozone exposure removes surface AlCH 3 * species. The AlCH 3 * species were converted to AlOCH 3 * (methoxy), Al(OCHO)* (formate), Al(OCOOH)* (carbonate), and AlOH* (hydroxyl) species. The TMA exposure then removes these species and reestablishes the AlCH 3 * species. Repeating the TMA and O 3 exposures in a sequential reaction sequence progressively deposited the Al 2 O 3 ALD film as monitored by the increase in absorbance for bulk Al 2 O 3 infrared features. The identification of formate species was confirmed by separate formaldehyde adsorption experiments. The formate species were temperature dependent and were nearly absent at temperatures g650 K. QMS analysis of the gas phase species revealed that the TMA reaction produced CH 4 . The ozone reaction produced mainly CH 4 with small amounts of C 2 H 4 (ethylene), CO, and CO 2 . Transmission electron microscopy (TEM) was also used to examine the Al 2 O 3 ALD films deposited on the ZrO 2 particles. These TEM images observed conformal Al 2 O 3 ALD films with thicknesses that were consistent with an Al 2 O 3 ALD growth rate of 1.1 Å/cycle. The surface species after the O 3 exposures and the mass spectrometry results lead to a very different mechanism for Al 2 O 3 ALD growth using TMA and O 3 compared with Al 2 O 3 ALD using TMA and H 2 O.

Challenges are encountered during atomic layer deposition (ALD) on large quantities of nanoparticles. The particles must be agitated or fluidized to perform the ALD surface reactions in reasonable times and to prevent the particles from being agglomerated by the ALD film. The high surface area of nanoparticles also demands efficient reactant usage because large quantities of reactant are required for the surface reactions to reach completion. The residence time of the reactant in a fluidized particle bed reactor may be too short for high efficiency if the ALD surface reactions have low reactive sticking coefficients. To address these challenges, a novel rotary reactor was developed to achieve constant particle agitation during static ALD reactant exposures. In the design of this new reactor, a cylindrical drum with porous metal walls was positioned inside a vacuum chamber. The porous cylindrical drum was rotated by a magnetically coupled rotary feedthrough. By rotating the cylindrical drum to obtain a centrifugal force of less than one gravitational force, the particles were agitated by a continuous “avalanche” of particles. In addition, an inert N2 gas pulse helped to dislodge the particles from the porous walls and provided an efficient method to purge reactants and products from the particle bed. The effectiveness of this rotary reactor was demonstrated by Al2O3 ALD on ZrO2 particles. A number of techniques including transmission electron microscopy, Fourier transform infrared spectroscopy, and x-ray photoelectron spectroscopy confirmed that the Al2O3 ALD film conformally coats the ZrO2 particles. Combining static reactant exposures with a very high surface area sample in the rotary reactor also provides unique opportunities for studying the surface chemistry during ALD.

An innovative process to uniformly incorporate dispersed nanoscale ceramic inclusions within a polymer matrix was demonstrated. Micron‐sized high density polyethylene particles were coated with ultrathin alumina films by atomic layer deposition in a fluidized bed reactor at 77°C. The deposition of alumina on the polymer particle surface was confirmed by Fourier transform infrared spectroscopy and X‐ray photoelectron spectroscopy. Conformal coatings of alumina were confirmed by transmission electron microscopy and focused ion beam cross‐sectional scanning electron microscopy. The results of inductively coupled plasma atomic emission spectroscopy suggested that there was a nucleation period. The results of scanning electron microscopy, particle size distribution, and surface area of the uncoated and nanocoated particles showed that there was no aggregation of particles during the coating process. The coated polymer particles were extruded by a heated extruder at controlled temperatures. The successful dispersion of the crushed alumina shells in the polymer matrix following extrusion was confirmed using cross‐sectional transmission electron microscopy. The dispersion of alumina flakes can be controlled by varying the polymer particle size.

Al 2 O 3 atomic layer deposition (ALD) is analyzed on ZrO 2 nanoparticles in a rotary reactor. This rotary reactor allows for static exposures and efficiently utilizes the reactants for ALD on high surface area nanoparticles. The Al 2 O 3 ALD is performed using exposures to Al(CH 3 ) 3 and H 2 O reactants. The pressure transients during these exposures are examined using a sequence of reactant micropulses. These micropulses are less than the required exposures for the ALD surface chemistry to reach completion. The pressure transients during identical sequential Al(CH 3 ) 3 and H 2 O micropulses change as the surface chemistry progresses to completion. These pressure transients allow the required saturation reactant exposure to be determined to maximize reactant usage. The ZrO 2 nanoparticles are coated using various numbers of Al(CH 3 ) 3 and H 2 O reactant exposures. The Al 2 O 3 ALD-coated ZrO 2 nanoparticles are subsequently analyzed using a number of techniques including scanning electron microscopy (SEM), transmission electron microscopy (TEM), Auger electron spectroscopy (AES), scanning AES (SAES), and X-ray photoelectron spectroscopy (XPS

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