TiO2 was deposited with atomic layer control on ZrO2 particles using alternating exposures of TiCl4 and H2O. Transmission Fourier transform infrared (FTIR) spectroscopy was used to monitor the sequential surface chemistry in vacuum. The ZrO2 particles initially displayed vibrational modes consistent with ZrOH* surface species. TiCl4 exposure at 600 K removed the surface hydroxyls and subsequent H2O exposure at 600 K produced TiOH* surface species. Repeating the TiCl4 and H2O exposures in an ABAB... reaction sequence deposited TiO2 with atomic layer control. The intensity of the bulk vibrational modes for TiO2 increased with the number of AB reaction cycles. The ZrO2 particles after TiO2 deposition were examined with transmission electron microscopy (TEM). The TEM images revealed ZrO2 particles encapsulated by conformal TiO2 films with a thickness of similar to16 Angstrom after 40 AB reaction cycles. These TEM images are consistent with a TiO2 atomic layer deposition (ALD) growth rate at 600 K of 0.4 Angstrom/AB cycle. (C) 2003 Elsevier B.V. All rights reserved.